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The unicellular soil-freshwater alga Chlamydomonas reinhardtii was found to secrete substances that mimic the activity of the N-acyl-l-homoserine lactone AHL signal molecules used by many bacteria for quorum sensing regulation of gene expression. Treatment of the soil bacterium Sinorhizobium meliloti with a partially purified LasR mimic from C.

The algal mimic was able to cancel the stimulatory effects of bacterial AHLs on the accumulation of seven of these proteins, providing evidence that the secretion of AHL mimics by the alga could be effective in disruption of quorum sensing in naturally encountered bacteria. Screening for compounds that affect the interaction between bacterial two-component signal transduction response regulator protein and cognate promoter DNA.

Bacterial signal transduction systems can be used as drug targets. The signal transduction targets fall into two groups--sensor kinases and response regulators. Previously reported studies describe hits that were thought to inactivate sensor kinases but on closer examination were found to act elsewhere instead; a possible reason for this is that full-length sensor kinases Casinoer paa nettetal nwsccone integral membrane proteins whose activity might reflect interaction with the cell membrane or with membrane components.

We describe a model system that instead is based Casino siderophores salmonella enteritidis virulence the interaction between a test compound and a response regulator in a homogeneous phase reaction. In this system, response regulator-DNA complex formation and its inhibition by a test compound are measured by fluorescence polarization. The model system should be readily adaptable to drug discovery based on other bacterial two-component s transduction systems.

Bacterial Degradation of Aromatic Compounds. Aromatic compounds are among the most prevalent and persistent pollutants in the environment. Petroleum-contaminated soil and sediment commonly contain a mixture of polycyclic aromatic hydrocarbons PAHs and heterocyclic aromatics.

Aromatics derived from industrial activities often have functional groups such as alkyls, halogens and nitro groups.

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Biodegradation is a major mechanism of removal of organic pollutants from a contaminated site. This review focuses on bacterial degradation pathways of selected aromatic compounds.

Catabolic pathways of naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene are described in detail. Bacterial catabolism of the heterocycles dibenzofuran, carbazole, dibenzothiophene, and dibenzodioxin is discussed. Bacterial catabolism of alkylated PAHs is summarized, followed by a brief discussion of proteomics and metabolomics as powerful tools for elucidation of biodegradation mechanisms.

Biological control biocontrol agents act on plants via numerous mechanisms, and can be used to protect plants from pathogens. Biocontrol agents can act directly as pathogen antagonists or competitors or indirectly to promote plant induced systemic resistance ISR.

Whether a biocontrol agent acts directly or indirectly depends on the specific strain and the pathosystem type. Emerging data suggest that bacterial VOCs also can directly inhibit fungal and plant growth.

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The aim of the current study was to differentiate direct and indirect mechanisms of bacterial VOC effects against Botrytis cinerea infection of Arabidopsis. Volatile emissions from Bacillus subtilis GB03 successfully protected Arabidopsis seedlings against B. First, we investigated the direct effects of bacterial VOCs on symptom development and different phenological stages of B.

Volatile emissions inhibited hyphal growth in a dose-dependent manner in vitro, and interfered with fungal attachment on the hydrophobic leaf surface.

Second, the optimized bacterial concentration that did not directly inhibit fungal growth successfully protected Arabidopsis from fungal infection, which indicates that bacterial VOC-elicited plant ISR has a more important role in biocontrol than direct inhibition of fungal growth on Arabidopsis. A bacterial volatile signal for biofilm formation.

Bacteria constantly monitor the environment they reside in and respond to potential changes in the environment through a variety of signal sensing and transduction mechanisms in a timely fashion.

Casino sidereal period of revolution planets signaling mechanisms often involve application of small, diffusible chemical molecules. Volatiles are a group of small air-transmittable chemicals that Casino siderophores salmonella enteritidis virulence produced universally by all kingdoms of organisms. Past studies have shown that volatiles can function as cell-cell communication signals not only within species, but also cross-species.

However, little is known about how the volatile-mediated signaling mechanism works. In our recent study Chen, et al. We also showed that the bacterium possesses an intertwined gene network to produce, secrete, sense, and respond to acetic acid, in stimulating biofilm formation. Interestingly, many of those genes are highly conserved in other bacterial species, raising the possibility that acetic acid may act as a volatile signal for cross-species communication.

Marine bacterial sources of bioactive compounds. Thousands of novel compounds have been isolated from various marine bacteria and tested for pharmacological properties, many of which are commercially available. Many more are being tested as potential bioactive compound at the preclinical and clinical stages. The growing interest in marine-derived antiviral compoundsalong with the development of new technology in marine cultures and extraction, will significantly expedite the current exploration of the marine environment for compounds with significant pharmacological applications, which will continue to be a promising strategy and new trend for modern medicine.

Marine actinomycetes and cyanobacteria are a prolific but underexploited source for the discovery of novel secondary metabolites. A potential method for biofilm dismantling is chemical interception of regulatory processes that are specifically involved in the biofilm mode of life. More recently, regulatory processes governed by two component regulatory systems and small non-coding RNAs have been increasingly investigated.

Here, we review novel findings and potentials of using small molecules to target and modulate these regulatory processes in the bacterium Pseudomonas aeruginosa to decrease its pathogenic potential. Mechanisms of bacterial resistance to chromium compounds.

Chromium is a non-essential and well-known toxic metal for microorganisms and plants. The widespread industrial use of this heavy metal has caused it to be considered as a serious environmental pollutant. Chromium exists in nature as two main species, the trivalent form, Cr IIIwhich is relatively innocuous, and the hexavalent form, Cr VIconsidered a more toxic species. At the intracellular level, however, Cr III seems to be responsible for most toxic effects of chromium.

Cr VI is usually present as the oxyanion chromate. Inhibition of sulfate membrane transport and oxidative damage to biomolecules are associated with the toxic effects of chromate in bacteria.

Several bacterial mechanisms of resistance to chromate have been reported. Chromate efflux by the ChrA transporter has been established in Pseudomonas aeruginosa and Cupriavidus metallidurans formerly Alcaligenes eutrophus and consists of an energy-dependent process driven by the membrane potential.

The CHR protein family, which includes putative ChrA orthologs, currently contains about sequences from all three domains of life. Chromate reduction is carried out by chromate reductases from diverse bacterial species generating Cr III that may be detoxified by other mechanisms. Most characterized enzymes belong to the widespread NAD P H-dependent flavoprotein family of reductases. Several examples of bacterial systems protecting from the oxidative stress caused by chromate have been described.

Other mechanisms of bacterial resistance to chromate involve the expression of components of the machinery for repair of DNA damage, and systems related to the homeostasis of iron and sulfur.

Bioremediation of organometallic compounds by bacterial degradation. The use of organometallic compounds in the environment is constantly increasing with increased technology and progress in scientific research. But since these compounds are fairly stable, as metallic bonds are stable, they are difficult to Casino siderophores salmonella enteritidis virulence or decompose naturally. The aim of this work was to isolate and characterize heterotrophic bacteria that can degrade organometallic compounds in this case 'ferrocene' and its derivatives.

A Gram-negative coccobacillus was isolated from a rusting iron pipe draining into a freshwater lake, which could utilize ferrocene as a sole source of carbon. Phylogenetic analysis based on 16S rDNA sequence suggested that the isolated organism resembled an environmental isolate of Bordetella. Ferrocene degradation was confirmed by plotting the growth curve of the bacterium in a medium with ferrocene as the sole source of carbon.

Further confirmation of degradation of ferrocene and its derivatives was done using Gas Chromatography Mass Spectroscopy. Since the bacterium degraded organometallic compounds and released the metal in liquid medium, it could be suggested that this organism can also be used for extracting metal ions from organo-metal containing wastes.

Catabolism of host-derived compounds during extracellular bacterial infections. Efficient catabolism of host-derived compounds is essential for bacterial survival and virulence. While these links in intracellular bacteria are well studied, such studies in extracellular bacteria lag behind, mostly for technical reasons.

The field has identified important metabolic pathways, but the mechanisms by which they impact infection and in particular, establishing the importance of a compound 's catabolism versus alternate metabolic roles has been difficult.

In this review we will examine evidence for catabolism during extracellular bacterial infections in animals and known or potential roles in virulence. In the process, we point out key gaps in the field that will require new or newly adapted techniques. Bacterial signaling and motility: This area is a home to rattlesnakes, sagebrush, abandoned gold mines, and compulsive gamblers.

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So there they were, about scientists gathered in the Aquarius Casino Resort, the largest hotel and casino in Laughlin, discussing the latest advances in the field. Aside from a brief excursion to an abandoned gold mine and a dinner cruise on the Colorado River, the scientists focused on nothing but their data and hypotheses, in spirited arguments and rebuttals, and outlined their visions and future plans in a friendly and open environment.

For that reason, this meeting report will not attempt to be comprehensive; instead it will first provide general background information on the central topics of the meeting and then highlight only a few talks that were of special interest to us and hopefully to the wider scientific community. We will also attempt to articulate some of the future directions or perspectives to the best of our abilities. The best known and understood bacterial motility mechanism is swimming powered by flagella.

The rotation of bacterial flagella drives this form of bacterial movement in an aqueous environment.

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  • 23 Sep Salmonella enterica serovar Typhimurium is a common facultative intracellular pathogen that causes food-borne gastroenteritis in millions of people worldwide . To overcome this limitation Salmonella produce two siderophores, enterobactin and salmochelin, in response to iron deprivation (for review, see.

A bacterial flagellum consists of a helical filament attached to the cell body through a complex structure known as the hook-basal body, which drives flagellar rotation. The essential components of the basal body are the MotA-MotB motor-stator proteins bound to the cytoplasmic membrane.

These stator proteins interact with proteins that comprise the supramembrane and cytoplasmic rings, which are components of the motor imbedded in the. Legionella pneumophila is a ubiquitous fresh-water bacterium which reproduces within its erstwhile predators, environmental amoeba, by subverting the normal pathway of phagocytosis and degradation.

The molecular mechanisms which confer resistance to amoeba are apparently conserved and also allow replication within macrophages. The intracellular localisation of L. In addition, the intracellular lifestyle of L.

The development of a single infection cycle intracellular replication assay using GFP-producing L. This fluorescence-based assay allows for continuous monitoring of intracellular replication rates, revealing the effect of bacterial gene deletions or drug treatment. To examine how perturbations of the host cell affect L. Further characterisation indicated that this compound caused specific growth inhibition of Legionella and Mycobacterium species, suggesting that it may act on a common bacterial target.

While these links in intracellular bacteria are well-studied, such studies in extracellular bacteria lag behind, mostly for technical reasons. Excessive flatulence can be a huge social problem. The purpose of this study was to design artificial flatus from bacterial volatile compounds to stimulate research into neutralizing measures.

Anaerobic bacteria, representing a broad spectrum, from a recognized international culture collection were included. The strains were incubated in an anaerobic jar.

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  1. 15 Dec Abstract. Data indicate that prevalence of specific serovars of Salmonella enterica in human foodborne illness is not correlated with their prevalence in feed. Given that feed is a suboptimal environment for S. enterica, it appears that survival in poultry feed may be an independent factor unrelated to virulence.:
    30 Mar environment selects for evolutionary gambling, and either conservative or Escherichia coli and Salmonella typhimurium for example, when .. virulence. Thus, rather than relying on self for secretion of virulence factors, S. pneumoniae kills some its relatives for this purpose which facilitates invasion of its. 1 Jun terium genes involved in bacterial physiology/virulence and plant genes involved in transformation and defense against nique developed for E. coli rather than for A. tumefaciens (Kado et al., ). Interestingly, other rhizogenes K84 produces a hydroxamate siderophore. Appl. Environ. Microbiol. 17 Dec Harrah's Casino Conference Center, Tunica, MS. September Hitchner, S., J. Schelhas, and Anaerobic respiration of elemental sulfur and thiosulfate by Shewanella oneidensis MR-1 requires psrA, a phsA homolog of Salmonella typhimurium LT2. Applied and Environmental Microbiology.
  2. studies, we will express this protein in E. coli (BL21 (DE3)) and use the histidine tag for affinity purification. .. significant role in the virulence of this organism: the Staphylococcal Cassette Chromosome mec (SCCmec) gene and structure of the protein, where the siderophore ligand normally binds will be randomized.:
    N-butryl homoserine lactone and N-hexanoyl homoserine lactone belonging to acyl homoserine lactone (AHL) family of signaling molecules were investigated for their effect on the biofilm formation (attachment and exopolymeric substance production) in the food-borne pathogens Escherichia coli, Salmonella enterica. All E. faecalis strains showed at least one virulence factor (either hemolysin or gelatinase), which emphasizes the importance of these studies in this species. Both L. Lactobacilli were tested for the inhibitory activity against selected strains of poultry enteropathogenic bacteria (Salmonella Enteritidis, Escherichia coli and. In addition, preformed biofilms of E. coli C, Salmonella Typhimurium, K. pneumoniae, and Salmonella enterica exposed to treatments were removed by Xoo produces a range of virulence factors, including EPS, extracellular enzyme, iron-chelating siderophores, and type III-secretion dependent effectors, which are.
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Many Proteobacteria produce acyl-homoserine lactones acyl-HSLs and employ them as dedicated cell-to-cell signals in a process known as quorum sensing.

We describe here the properties of a second isolate, Arthrobacter strain VAI-A, obtained from the same enrichment culture that yielded V. Although strain VAI-A grew rapidly and exponentially on a number of substrates, it grew only slowly and aberrantly i.

Increasing the culture pH markedly improved the growth rate in media containing this substrate but did not abolish the aberrant kinetics. The observed growth was remarkably similar to the known kinetics of the pH-influenced half-life of acyl-HSLs, which decay chemically to yield the corresponding acyl-homoserines. Strain VAI-A grew rapidly and exponentially when provided with an acyl-homoserine as the sole energy or nitrogen source.

The isolate was also able to utilize HSL as a sole source of nitrogen but not as energy for growth. Moreover, the acyl-HSL-dependent growth rate and yield of the coculture were dramatically superior to those of the monocultures. This suggested that the original coenrichment of these two organisms from the same soil sample was not coincidental and that consortia may play a role in quorum signal turnover and mineralization.

The fact that Arthrobacter strain VAI-A utilizes the two known nitrogenous degradation products of acyl-HSLs, acyl-homoserine and HSL, begins to explain why none of the three compounds are known to accumulate in the environment. N-hexanoyl-L-homoserine lactone , a mediator of bacterial quorum-sensing regulation, exhibits plant-dependent stability and may be inactivated by germinating Lotus corniculatus seedlings.

The half-life of N-hexanoyl-l-homoserine lactone C6-HSL was determined under various pH and temperature conditions, and in several plant environments. C6-HSL was sensitive to alkaline pH, a process that was also temperature-dependent. In addition, C6-HSL disappeared from plant environments, i. The disappearance was rapid at the root system of legume plants such as clover or Lotus, and slow or non-existent at the root system of monocots such as wheat or corn.

These variable kinetics were not dependent upon pH changes that may have affected the growth media of the plants. Preliminary investigation revealed that the inactivating ability is temperature-dependant and possibly of enzymatic origin.

Sponges and bacteria have lived together in complex consortia for million years. As filter feeders, sponges prey on bacteria. Nevertheless, some bacteria are associated with sponges in symbiotic relationships. To enable this association, sponges and bacteria are likely to have developed molecular communication systems.

These may include molecules such as N-acyl-L-homoserine lactones , produced by Gram-negative bacteria also within sponges. In this study, we examined the role of Noxododecanoyl-L-homoserine lactone 3-oxo-CHSL on the expression of immune and apoptotic genes of the host sponge Suberites domuncula. This molecule seemed to inhibit the sponge innate immune system through a decrease of the expression of genes coding for proteins sensing the bacterial membrane: Then, we demonstrated the differential expression of proteins in presence of this 3-oxo-CHSL using 3D sponge cell cultures.

The genetic expression of some of these proteins was subsequently followed. We propose that the 3-oxo-CHSL may participate in the tolerance of the sponge apoptotic and immune systems towards the presence of bacteria. This study is the first report of a bacterial secreted molecule acting on. Insights into an Intimate Inter-Kingdom Dialogue. Bacterial communication signals , acylated homoserine lactones AHLs , were extracted from samples of commercial bean sprouts undergoing soft-rot spoilage.

AHL-producing bacteria Enterobacteriaceae and pseudomonads were isolated from commercial sprouts, and strains that were both proteolytic and pectinolytic were capable of causing soft-rot spoilage in bean sprouts. Thin-layer chromatography and liquid chromatography-high-resolution mass spectrometry revealed the presence of Noxo-hexanoyl-l-homoserine lactone in spoiled bean sprouts and in extracts from pure cultures of bacteria.

During normal spoilage, the pH of the sprouts increased due to proteolytic activity, and the higher pH probably facilitated the activity of pectate lyase.

The AHL synthetase gene I gene from a spoilage Pectobacterium was cloned, sequenced, and inactivated in the parent strain. Spoilage of laboratory bean sprouts inoculated with the AHL-negative mutant was delayed compared to sprouts inoculated with the wild type, and the AHL-negative mutant did not cause the pH to rise. Compared to the wild-type strain, the AHL-negative mutant had significantly reduced protease and pectinase activities and was negative in an iron chelation siderophore assay.

This is the first study demonstrating AHL regulation of iron chelation in Enterobacteriaceae. The present study clearly demonstrates that the bacterial spoilage of some food products is influenced by quorum-sensing-regulated phenotypes, and understanding these processes may be useful in the development of novel food preservation additives that specifically block the quorum-sensing systems. N-Acyl-homoserine- lactones AHLs are bacterial quorum-sensing signaling molecules that regulate population density.

Recent evidence demonstrates their roles in plant defense responses and root development. Hydrogen peroxide H2O2 , nitric oxide NO , and cyclic GMP cGMP are essential messengers that participate in various plant physiological processes, but how these messengers modulate the plant response to N-acyl-homoserine- lactone signals remains poorly understood.

Here, we show that the Noxo-decanoyl-homoserine- lactone 3-O-CHL , in contrast to its analog with an unsubstituted branch chain at the C3 position, efficiently stimulated the formation of adventitious roots and the expression of auxin-response genes in explants of mung bean Vigna radiata seedlings.

These results suggest that 3-O-CHL, unlike its analog with an unmodified branch chain at the C3 position, can accelerate auxin-dependent adventitious root formation, possibly via H2O2- and NO-dependent cGMP signaling in mung bean seedlings. Bacterial signaling and motility: This area is a home to rattlesnakes, sagebrush, abandoned gold mines, and compulsive gamblers. What better venue could scientists possibly dream of for a professional meeting? So there they were, about scientists gathered in the Aquarius Casino Resort, the largest hotel and casino in Laughlin, discussing the latest advances in the field.

Aside from a brief excursion to an abandoned gold mine and a dinner cruise on the Colorado River, the scientists focused on nothing but their data and hypotheses, in spirited arguments and rebuttals, and outlined their visions and future plans in a friendly and open environment. For that reason, this meeting report will not attempt to be comprehensive; instead it will first provide general background information on the central topics of the meeting and then highlight only a few talks that were of special interest to us and hopefully to the wider scientific community.

We will also attempt to articulate some of the future directions or perspectives to the best of our abilities. The best known and understood bacterial motility mechanism is swimming powered by flagella. The rotation of bacterial flagella drives this form of bacterial movement in an aqueous environment. A bacterial flagellum consists of a helical filament attached to the cell body through a complex structure known as the hook-basal body, which drives flagellar rotation.

The essential components of the basal body are the MotA-MotB motor-stator proteins bound to the cytoplasmic membrane. These stator proteins interact with proteins that comprise the supramembrane and cytoplasmic rings, which are components of the motor imbedded in the. Quorum sensing QS is a bacterial cell-to-cell communication system controlling QS-mediated genes which is synchronized with the population density.

The regulation of specific gene activity is dependent on the signaling molecules produced, namely N-acyl homoserine lactones AHLs.

We report here the identification and characterization of AHLs produced by bacterial strain ND07 isolated from a Malaysian fresh water sample. Molecular identification showed that strain ND07 is clustered closely to Pseudomonas cremoricolorata. Spent culture supernatant extract of P. Using high resolution triple quadrupole liquid chromatography-mass spectrometry, it was confirmed that P.

Responses of the Microalga Chlorophyta sp. Bacteria and microalgae often coexist during the recycling of microalgal bioresources in wastewater treatment processes. Although the bacteria may compete with the microalgae for nutrients, they could also facilitate microalgal harvesting by forming algal- bacterial aggregates.

However, very little is known about interspecies interactions between bacteria and microalgae. In this study, we investigated the responses of a model microalga, Chlorophyta sp. Fluorescence intensity of the aromatic proteins had significant P Influence of bacterial N-acyl-homoserine lactones on growth parameters, pigments, antioxidative capacities and the xenobiotic phase II detoxification enzymes in barley and yam bean.

Bacteria are able to communicate with each other and sense their environment in a population density dependent mechanism known as quorum sensing QS. N-acyl-homoserine lactones AHLs are the QS signaling compounds of Gram-negative bacteria which are frequent colonizers of rhizospheres.

While cross-kingdom signaling and AHL-dependent gene expression in plants has been confirmed, the responses of enzyme activities in the eukaryotic host upon AHLs are unknown.

Because the yield of a crop plant should not be negatively influenced, we have also checked for growth and root parameters. While plant growth and pigment contents in both plants showed only small responses to the applied AHLs, AHL treatment triggered tissue- and compound-specific changes in the activity of important detoxification enzymes.

Other detoxification enzymes reacted similarly within this range, with interesting clusters of positive or negative answers toward AHL treatment. In general the changes on the enzyme level were more severe in barley than in yam bean which might be due to the different abilities of the plants to. Influence of bacterial N-acyl-homoserine lactones on growth parameters, pigments, antioxidative capacities and the xenobiotic phase II detoxification enzymes in barley and yam bean.

Insights into plant immunity signalling: The interaction between a bacterial pathogen and its potential plant host develops from a complex combination of bacterial and plant elements, which determines either the establishment of resistance or the development of disease. The use of virulence assays based on competitive index in mixed infections constitutes a powerful tool for the analysis of bacterial virulence factors.

In this work, we describe how the use of competitive index assays also constitutes an alternative approach for the analysis of plant immunity, to determine the contribution of different elements to bacterial recognition or immunity signaling. Pathogenic bacteria use interconnected multi-layered regulatory networks, such as quorum sensing QS networks to sense and respond to environmental cues and external and internal bacterial cell signals , and thereby adapt to and exploit target hosts.

Despite the many advances that have been made in understanding QS regulation, little is known regarding how these inputs are integrated and processed in the context of multi-layered QS regulatory networks.

The aim of this work was to elucidate paradigmatically the complex relationships between multi-layered regulatory QS circuitries, their signaling molecules, and the environmental cues to which they respond. Our findings revealed positive and negative homeostatic regulatory loops that fine-tune the MvfR regulon via a multi-layered dependent homeostatic regulation of the cell-cell signaling molecules PQS and HHQ, and interplay between these molecules and iron.

We discovered that the MvfR regulon component PqsE is a key mediator in orchestrating this homeostatic regulation, and in establishing a connection to the QS rhlR system in cooperation with RhlR. Our results show that P.

Our findings underscore the importance of the homeostatic interplay that balances competition within and between QS systems via cell-cell signaling molecules and environmental cues in the control of virulence gene expression. Elucidation of the fine-tuning of this complex relationship offers novel insights into the regulation of these systems and may inform strategies designed to limit infections caused by P.

Formyl peptide receptors FPRs are G-protein-coupled receptors that function as chemoattractant receptors in innate immune responses. Here we perform systematic structure-function analyses of FPRs from six mammalian species using structurally diverse FPR peptide agonists and identify a common set of conserved agonist properties with typical features of pathogen-associated molecular patterns.

Guided by these results, we discover that bacterial signal peptides, normally used to translocate proteins across cytoplasmic membranes, are a vast family of natural FPR agonists. N-terminally formylated signal peptide fragments with variable sequence and length activate human and mouse FPR1 and FPR2 at low nanomolar concentrations, thus establishing FPR1 and FPR2 as sensitive and broad signal peptide receptors.

The vomeronasal receptor mFpr-rs1 and its sequence orthologue hFPR3 also react to signal peptides but are much more narrowly tuned in signal peptide recognition. Furthermore, all signal peptides examined here function as potent activators of the innate immune system. They elicit robust, FPR-dependent calcium mobilization in human and mouse leukocytes and trigger a range of classical innate defense mechanisms, such as the production of reactive oxygen species, metalloprotease release, and chemotaxis.

Thus, bacterial signal peptides constitute a novel class of immune activators that are likely to contribute to mammalian immune defense against bacteria.

This evolutionarily conserved detection mechanism combines structural promiscuity with high specificity and enables discrimination between bacterial and eukaryotic signal sequences. With at least , predicted sequences, bacterial signal peptides represent the largest and structurally most heterogeneous class of G-protein-coupled receptor agonists currently known for the innate immune system.

GTPases in bacterial cell polarity and signalling. In bacteria, large G domain GTPases have well-established functions in translation, protein translocation, tRNA modification and ribosome assembly. Recent data have revealed that small Ras-like GTPases as well as large G domain GTPases in bacteria function in the regulation of cell polarity, signal transduction and possibly also in cell division.

Moreover, large dynamin-like GTPases in bacteria may function in cell division. Thus, the function of GTPases in bacteria may be as pervasive as in eukaryotes. Isoalantolactone, a sesquiterpene lactone , possesses anti-fungal as well as cytotoxic properties.

In this study, the effects of Isoalantolactone on cell viability, cell cycle, and apoptosis were investigated in human gastric adenocarcinoma SGC cells.

The results demonstrated that Isoalantolactone induced morphological changes and decreased cell viability. Britannin, a sesquiterpene lactone , inhibits proliferation and induces apoptosis through the mitochondrial signaling pathway in human breast cancer cells. Induction of apoptosis in cancer cells can be a promising treatment method in cancer therapy. Naturally derived products had drawn growing attention as agent in cancer therapy.

The main target of anticancer drugs may be distinct, but eventually, they lead to identical cell death pathway, which is apoptosis. Here, we indicated that britannin, a sesquiterpene lactone isolated from Asteraceae family, has antiproliferative activity on the MCF-7 and MDA-MB human breast cancer cells. The Western blot analysis showed that the expression of Bcl-2 was noticeably decreased in response to britannin treatment, while the expression of Bax protein was increased, which were positively correlated with elevated expression of p Taken together, these results suggest that britannin inhibits growth of MCF-7 and MDA-MB breast cancer cells through the activation of the mitochondrial apoptotic pathway and may potentially serve as an agent for breast cancer therapy.

Ample evidence exists showing that eukaryotic signal molecules synthesized and released by the host can activate the virulence of opportunistic pathogens. The sensitivity of prokaryotes to host signal molecules requires the presence of bacterial sensors. These prokaryotic sensors, or receptors, have a double function: As messengers are generally unable to freely cross the bacterial membrane, they require either the presence of sensors anchored in the membrane or transporters allowing direct recognition inside the bacterial cytoplasm.

Since the discovery of quorum sensing, it was established that the production of virulence factors by bacteria is tightly growth-phase regulated. It is now obvious that expression of bacterial virulence is also controlled by detection of the eukaryotic messengers released in the micro-environment as endocrine or neuro-endocrine modulators.

In the presence of host physiological stress many eukaryotic factors are released and detected by Gram-negative bacteria which in return rapidly adapt their physiology.

Escherichia coli sensitivity to the neurohormones of the catecholamines family appears relayed by a recently identified bacterial adrenergic receptor. In the present review, we will describe the mechanisms by which various eukaryotic signal molecules produced by host may activate Gram-negative bacteria virulence. Particular attention will be paid to Pseudomonas, a genus whose representative species, P. The discussion will be particularly focused on the pivotal role played by these new types of pathogen sensors from the sensing to the transduction mechanism involved in.

HAMP domain conformers that propagate opposite signals in bacterial chemoreceptors. We identify two HAMP conformations distinguished by a four- to two-helix packing transition at the C-termini that send opposing signals in bacterial chemoreceptors.

Crystal structures of signal -locked mutants establish the observed structure-to-function relationships. Pulsed dipolar electron spin resonance spectroscopy of spin-labeled soluble receptors active in cells verify that the crystallographically defined HAMP conformers are maintained in the receptors and influence the structure and activity of downstream domains accordingly.

Another HR2 variant displays an inverted response with respect to ligand and demonstrates the fine energetic balance between "on" and "off" conformers. Our findings directly correlate in vivo signaling with HAMP structure, stability, and dynamics to establish a comprehensive model for HAMP-mediated signal relay that consolidates existing views on how conformational signals propagate in receptors.

Moreover, we have developed a rational means to manipulate HAMP structure and function that may prove useful in the engineering of bacterial taxis responses. Lung cancer is the leading cause of cancer deaths worldwide and current therapies fail to treat this disease in majority of cases. Antrodia camphorata is a medicinal mushroom being widely used as food dietary supplement for cancer prevention. However, the molecular mechanisms of antrocin-mediated anticancer effects remain unclear.

We further demonstrated that antrocin suppressed both constitutively activated and interleukin 6-induced STAT3 phosphorylation and its subsequent nuclear translocation. Such inhibition is found to be achieved through the suppression of JAK2 and interaction between STAT3 and extracellular signal -regulated kinase. Such dual interruption of JAK2 and STAT3 pathways also induced downregulation of antiapoptotic protein mcl-1 and increased caspase-3 expression.

In vivo intraperitoneal administration of antrocin significantly suppressed the growth of lung cancer tumor xenografts. Here we explore the feasibility of extracting bacterial protein signals relevant to CD, by interrogating myriads of intestinal bacterial proteomes from a small number of patients and healthy controls. Then we used selected reaction monitoring SRM to confirm a set of candidates.

In parallel, we used 16S rRNA gene sequencing for an integrated analysis of gut ecosystem structure and functions. Many proteins, largely derived from Bacteroides species, were over-represented, while under-represented proteins were mostly from Firmicutes and some Prevotella members. Most overabundant proteins could be confirmed using SRM. They correspond to functions allowing opportunistic pathogens to colonise the mucus layers, breach the host barriers and invade the mucosae, which could still be aggravated by decreased host-derived pancreatic zymogen granule membrane protein GP2 in CD patients.

Moreover, although the abundance of most protein groups reflected that of related bacterial populations, we found a specific independent regulation of bacteria-derived cell envelope proteins. Conclusions This study provides the first evidence that quantifiable bacterial protein signals are associated with CD, which can have a profound impact on future molecular diagnosis.

Bacterial protein signals are associated with Crohn's disease. No Crohn's disease CD molecular maker has advanced to clinical use, and independent lines of evidence support a central role of the gut microbial community in CD.

This study provides the first evidence that quantifiable bacterial protein signals are associated with CD, which can have a profound impact on future molecular diagnosis. For permission to use where not already granted under a licence please go to http: The Pseudomonas aeruginosa quorum sensing signal molecule N- 3-oxododecanoyl homoserine lactone enhances keratinocyte migration and induces Mmp13 gene expression in vitro. Re-epithelialization is an essential step of wound healing involving three overlapping keratinocyte functions: While quorum sensing QS is a cell density-dependent signaling system that enables bacteria to regulate the expression of certain genes, the QS molecule N- 3-oxododecanoyl homoserine lactone AHL exerts effects also on mammalian cells in a process called inter-kingdom signaling.

Recent studies have shown that AHL improves epithelialization in in vivo wound healing models but detailed understanding of the molecular and cellular mechanisms are needed. The present study focused on the AHL as a candidate reagent to improve wound healing through direct modulation of keratinocyte's activity in the re-epithelialization process.

Results indicated that AHL enhances the keratinocyte's ability to migrate in an in vitro scratch wound healing model probably due to the high Mmp13 gene expression analysis after AHL treatment that was revealed by real-time RT-PCR. Inhibition of activator protein 1 AP-1 signaling pathway completely prevented the migration of keratinocytes, and also resulted in a diminished Mmp13 gene expression, suggesting that AP-1 might be essential in the AHL-induced migration.

Taken together, these results imply that AHL is a promising candidate molecule to improve re-epithelialization through the induction of migration of keratinocytes. Further investigation is needed to clarify the mechanism of action and molecular pathway of AHL on the keratinocyte migration process.

The cooling water systems are used to remove heat generated in the various industries. Biofouling of the cooling water systems causes blocking of condenser pipes and the heat exchanger tubes. In many Gram-negative bacteria, N-acylhomoserine lactone AHL are used as quorum-sensing signal molecule and associated with biofilm formation.

To investigate the relationship between quorum sensing and biofouling in the cooling water system, we isolated a total of bacterial strains from the five cooling water systems, and screened for AHL production. To the best of our knowledge, B. AHLs extracted from the culture supernatants of B. AHLs produced by B. AHLs produced by Lysobacter sp.

This is the first report of identification of AHLs produced by B. The Pseudomonas aeruginosa quorum-sensing signal N- 3-oxododecanoyl homoserine lactone can accelerate cutaneous wound healing through myofibroblast differentiation in rats.

Quorum sensing is a cell density-dependent gene regulation system in bacteria. N- 3-oxododecanoyl homoserine lactone 3-oxo-CHSL is used in the las quorum-sensing system in Pseudomonas aeruginosa, which is an opportunistic pathogen that causes many human diseases. Although many studies have investigated the sole effects of quorum sensing on several types of mammalian cells, including lung cells, little is known about the effects of quorum sensing on the cells associated with wound healing.

To better understand the mechanism of bacterial wound infection, we investigated the effects of 3-oxo-CHSL on cells using a rat full-thickness wound-healing model. We found that the wound contraction was significantly increased at 24 h after the administration of 3-oxo-CHSL to the surface of granulation tissue. Differentiation of fibroblasts to myofibroblasts was induced in the in vivo wound-healing model and was confirmed in vitro using the rat fibroblastic cell line Rat This finding suggested that Cox-2 upregulation may be related to the inflammatory findings in the histological examinations, in which infiltrating polymorphonuclear neutrophils were observed at the wound site.

Taken together, these results imply that mammals have a potential defense system against invading pathogens by responding to the presence of 3-oxo-CHSL and inducing the differentiation of fibroblasts to myofibroblasts as well as inflammation for accelerating wound healing. Detection of bacterial signaling molecules in liquid or gaseous environments. The detection of bacterial signaling molecules in liquid or gaseous environments has been occurring in nature for billions of years.

More recently, man-made materials and systems has also allowed for the detection of small molecules in liquid or gaseous environments. This chapter will outline some examples of these man-made detection systems by detailing several acoustic-wave sensor systems applicable to quorum sensing. More importantly though, a comparison will be made between existing bacterial quorum sensing signaling systems, such as the Vibrio harveyi two-component system and that of man-made detection systems, such as acoustic-wave sensor systems and digital communication receivers similar to those used in simple cell phone technology.

It will be demonstrated that the system block diagrams for either bacterial quorum sensing systems or man-made detection systems are all very similar, and that the established modeling techniques for digital communications and acoustic-wave sensors can also be transformed to quorum sensing systems.

Inflammasomes - molecular platforms for caspase-1 activation - have emerged as common hubs for a number of pathways that detect and respond to bacterial pathogens. In this review we discuss signal transduction leading to 'canonical' and 'non-canonical' activation of caspase-1 through the involvement of upstream caspases. Recent studies have identified a growing number of regulatory networks involving guanylate binding proteins, protein kinases, ubiquitylation and necroptosis related pathways that modulate inflammasome responses and immunity to bacterial infection.

By being able to respond to extracellular, vacuolar and cytosolic bacteria, their cytosolic toxins or ligands for cell surface receptors, inflammasomes have emerged as important sentinels of infection. Paper strip whole cell biosensors: Herein, we report the development of a novel, inexpensive, and portable filter-paper-based strip biosensor for the detection of bacterial quorum sensing signaling molecules, N-acylhomoserine lactones AHLs.

AHLs are generally employed by Gram-negative bacteria for their cell-cell communication to control expression of specialized genes, such as those involved in biofilm formation and production of virulence factors, in a population-density-dependent manner. First, a bacterial cell-based sensing system employing components of AHL-mediated QS regulatory system as recognition elements and beta-galactosidase as the reporter protein was designed and developed.

The bacterial -sensing cells were then liquid-dried on strips of filter paper. The paper strip biosensor was able to detect low AHL concentrations down to 1 x 10 -8 M. Furthermore, it was successfully applied to the detection of AHLs in physiological samples, such as saliva.

The filter-paper-based sensing strips could provide reproducible results upon storage at 4 degrees C for at least 3 months. In conclusion, a filter-paper-based strip biosensor was developed that allows for visual, fast, and convenient detection of AHLs in a dose-dependent manner in a test sample. In addition, it does not require expensive equipment or trained personnel and allows ease of transportation and storage.

Therefore, we envision that this biosensor will serve as a simple and economical portable field kit for on-site monitoring of AHL in a variety of clinical and environmental samples. Improvement of bioelectrochemical property and energy recovery by acylhomoserine lactones AHLs in microbial electrolysis cells MECs.

Quorum sensing QS has been extensively studied as a cell-cell communication system, where small chemical signal molecules acylhomoserine lactones , AHLs can regulate the bacterial communications in bioelectrochemical systems via chemical signaling and electric signaling. In this study, electrochemical activity of bio-anode is substantially promoted by adding two kinds of AHLs with different chain length at the stage of community formation in microbial electrolysis cells MECs.

The highest yield is up to 3. Evaluated on applied voltage, energy efficiency is increased to Signaling factor interactions with polysaccharide aggregates of bacterial biofilms. Biofilms are surface-attached colonies of bacteria embedded in an extracellular polymeric substance EPS. Inside the eukaryotic hosts, bacterial biofilms interact with the host cells through signaling factors SFs. These signaling processes play important roles in the interaction between bacteria and host cells and the outcome of infections and symbiosis.

However, how host immune factors diffuse through biofilms is not well understood. Here, we describe synergistic molecular dynamics and experimental approaches for studying the translocation of signaling factors through polysaccharide chain aggregates present in the extracellular matrix of bacterial biofilms. The effect of polysaccharide chain degradation on the energetics of SF-EPS interactions was examined by simulating an EPS consisting of various polysaccharide chain lengths.

It is shown that the SF stabilization energy, defined as the average potential of mean force difference between the environments outside and within the matrix, increases linearly with decreasing chain length. This effect has been explained based on the changes in the polysaccharide configurations around the SF. Specifically, shorter chains are packed tightly around the SF, promoting favorable SF-EPS interactions, while longer chains are packed loosely resulting in screening of interactions with neighboring chains.

We further investigated the translocation of SFs through the host cell membrane using molecular dynamics simulations. The agreement of computational and experimental findings motivates future computational studies using a more detailed description of the EPS aimed at understanding the role of the extracellular matrix on biofilm drug resistance.

The cell-to-cell communication of microorganisms is known to be via exertion of certain chemical compounds signal molecules and is referred to as quorum sensing QS. QS phenomenon is widespread in microbial communities. Several Gram-positive and Gram-negative bacteria and fungi use lactone -containing compounds e. The ability of microorganisms to metabolise these compounds and the mechanisms they employ for this purpose are not clearly understood. Many studies, however, have focused on identifying AHL and other lactone -degrading enzymes produced by bacteria and fungi.

Various strains that are able to utilise these signalling molecules as carbon and energy sources have also been isolated. In addition, several reports have provided evidence on the involvement of lactones and lactone -degrading enzymes in numerous biological functions.

These studies, although focused on processes other than metabolism of lactone signalling molecules, still provide insights into further understanding of the mechanisms employed by various microorganisms to metabolise the QS compounds. Inhibiting N-acyl-homoserine lactone synthesis and quenching Pseudomonas quinolone quorum sensing to attenuate virulence. Bacteria sense their own population size, tune the expression of responding genes, and behave accordingly to environmental stimuli by secreting signaling molecules.

This phenomenon is termed as quorum sensing QS. By exogenously manipulating the signal transduction bacterial population behaviors could be controlled, which may be done through quorum quenching QQ. QS related regulatory networks have been proven their involvement in regulating many virulence determinants in pathogenic bacteria in the course of infections.

Interfering with QS signaling system could be a novel strategy against bacterial infections and therefore requires more understanding of their fundamental mechanisms.

Here we review the development of studies specifically on the inhibition of production of N-acyl-homoserine lactone AHL , a common proteobacterial QS signal.

The opportunistic pathogen, Pseudomonas aeruginosa, equips the alkylquinolone AQ -mediated QS which also plays crucial roles in its pathogenicity. The studies in QQ targeting on AQ are also discussed. Klebsiella pneumoniae is one of the most common Gram-negative bacterial pathogens in clinical practice. It is associated with a wide range of disorders, ranging from superficial skin and soft tissue infections to potentially fatal sepsis in the lungs and blood stream. Quorum sensing, or bacterial cell-cell communication, refers to population density-dependent gene expression modulation.

Quorum sensing in Proteobacteria relies on the production and sensing of signaling molecules which are mostly N-acylhomoserine lactones. Here, we report the identification of a multidrug resistant clinical isolate, K. We further confirmed quorum sensing activity in this strain with the use of high resolution tandem liquid chromatography quadrupole mass spectrometry and provided evidence K.

To the best of our knowledge, this is the first report on the production of N-hexanoylhomoserine lactone C6-HSL in clinical isolate K. Short chain N-acylhomoserine lactone production by clinical multidrug resistant Klebsiella pneumoniae strain CSG The unicellular soil-freshwater alga Chlamydomonas reinhardtii was found to secrete substances that mimic the activity of the N-acyl-l-homoserine lactone AHL signal molecules used by many bacteria for quorum sensing regulation of gene expression.

Treatment of the soil bacterium Sinorhizobium meliloti with a partially purified LasR mimic from C. The algal mimic was able to cancel the stimulatory effects of bacterial AHLs on the accumulation of seven of these proteins, providing evidence that the secretion of AHL mimics by the alga could be effective in disruption of quorum sensing in naturally encountered bacteria.

Chemoreceptors are crucial components in the bacterial sensory systems that mediate chemotaxis. Chemotactic responses exhibit exquisite sensitivity, extensive dynamic range and precise adaptation. The mechanisms that mediate these high-performance functions involve not only actions of individual proteins but also interactions among clusters of components, localized in extensive patches of thousands of molecules.

Recently, these patches have been imaged in native cells, important features of chemoreceptor structure and on—off switching have been identified, and new insights have been gained into the structural basis and functional consequences of higher order interactions among sensory components. These new data suggest multiple levels of molecular interactions, each of which contribute specific functional features and together create a sophisticated signaling device.

Modulation of connexin signaling by bacterial pathogens and their toxins. Inherent to their pivotal tasks in the maintenance of cellular homeostasis, gap junctions, connexin hemichannels, and pannexin hemichannels are frequently involved in the dysregulation of this critical balance. The present paper specifically focuses on their roles in bacterial infection and disease. In particular, the reported biological outcome of clinically important bacteria including Escherichia coli, Shigella flexneri, Yersinia enterocolitica, Helicobacter pylori, Bordetella pertussis, Aggregatibacter actinomycetemcomitans, Pseudomonas aeruginosa, Citrobacter rodentium, Clostridium species, Streptococcus pneumoniae, and Staphylococcus aureus and their toxic products on connexin- and pannexin-related signaling in host cells is reviewed.

Particular attention is paid to the underlying molecular mechanisms of these effects as well as to the actual biological relevance of these findings. Burkholderia species, the Burkholderia cepacia complex. In Burkholderia cenocepacia, there are two luxI-luxR homolog pairs. The primary product of Quorum sensing in Burkholderia cepacia Diversity of culturable bacterial communities in the intestinal tracts of goldfish Carassius auratus and their ability to produce N-acyl homoserine lactone.

Intestinal bacteria isolated from goldfish Carassius auratus were identified based on 16 ribosomal RNA rRNA gene sequences and screened for their ability to produce N-acyl homoserine lactone AHL , an autoinducer of the quorum sensing QS system.

Among these genera, the two most abundant species were Aeromonas veronii isolates and Shewanella xiamenensis In addition, obligate anaerobes consisting of Cetobacterium somerae isolates , Clostridium frigidicarnis 2 , and Cetobacterium sp.

One hundred seventy isolates Total viable counts ranged from 1. In addition, members of the genera Aeromonas and Shewanella appeared to communicate with each other by using the QS system to some extent when the concentration of AHL reaches a certain threshold. It is therefore suggested that bacteria with the ability to disrupt AHL secretion in intestinal environments are potential candidates for probionts for preventing opportunistic infections in freshwater fish such as goldfish.

Kravchenko, Vladimir; Garner, Amanda L. This discovery unveils a previously unrecognized symbiotic link between bacteria and host immunosurveillance. Quorum sensing in Aeromonas hydrophila and Aeromonas salmonicida: Spent culture supernatants from both Aeromonas hydrophila and Aeromonas salmonicida activate a range of biosensors responsive to N-acylhomoserine lactones AHLs.

The genes for a quorum sensing signal generator and a response regulator were cloned from each Aeromonas species and termed ahyRI and asaRI, respectively. Protein sequence homology analysis places the gene products within the growing family of LuxRI homologs. Downstream of both ahyI and asaI is a gene with close homology to iciA, an inhibitor of chromosome replication in Escherichia coli, a finding which implies that in Aeromonas, cell division may be linked to quorum sensing. The major signal molecule synthesized via both AhyI and AsaI was purified from spent culture supernatants and identified as N- butanoyl -L-homoserine lactone BHL by thin-layer chromatography, high-pressure liquid chromatography analysis, and mass spectrometry.

Transcriptional reporter studies with ahyI:: These data add A. Two reporter strains were established to identify novel biomolecules interfering with bacterial communication quorum sensing [QS]. The basic design of these Escherichia coli-based systems comprises a gene encoding a lethal protein fused to promoters induced in the presence of QS signal molecules. The second reporter strain AI1-QQ. Bacteria isolated from the surfaces of several marine eukarya were screened for quorum-quenching QQ activities using the established reporter systems AI1-QQ.

Out of 34 isolates, two interfered with acylated homoserine lactone AHL signaling , five interfered with AI-2 QS signaling , and 10 were demonstrated to interfere with both signal molecules. Evaluation of the respective heterologously expressed and purified QQ proteins confirmed their ability to interfere with the AHL and AI-2 signaling processes.

Microbial lactonization of gamma,delta-epoxy esters. The ability of 19 microorganisms to perform the enantioselective lactonization of racemic gamma,delta-epoxy ester 3a and its 7-methyl homolog 3b was checked.

Evolutionary theory of bacterial quorum sensing: The term quorum sensing QS is used to describe the communication between bacterial cells, whereby a coordinated population response is controlled by diffusible molecules produced by individuals. QS has not only been described between cells of the same species intraspecies , but also between species interspecies and between bacteria and higher organisms inter-kingdom.

The fact that QS-based communication appears to be widespread among microbes is strange, considering that explaining both cooperation and communication are two of the greatest problems in evolutionary biology. From an evolutionary perspective, intraspecies signalling can be explained using models such as kin selection, but when communication is described between species, it is more difficult to explain.

It is probable that in many cases this involves QS molecules being used as 'cues' by other species as a guide to future action or as manipulating molecules whereby one species will 'coerce' a response from another.

In these cases, the usage of QS molecules cannot be described as signalling. This review seeks to integrate the evolutionary literature on animal signalling with the microbiological literature on QS, and asks whether QS within bacteria is true signalling or whether these molecules are also used as cues or for the coercion of other cells. The contribution of cell-cell signaling and motility to bacterial biofilm formation.

Many bacteria grow attached to a surface as biofilms. Several factors dictate biofilm formation, including responses by the colonizing bacteria to their environment. Here we review how bacteria use cell-cell signaling also called quorum sensing and motility during biofilm formation. Specifically, we describe quorum sensing and surface motility exhibited by the bacterium Pseudomonas aeruginosa, a ubiquitous environmental organism that acts as an opportunistic human pathogen in immunocompromised individuals.

Surface motility affects the assembly and architecture of biofilms, and some aspects of motility are also influenced by quorum sensing. While some genes and their function are specific to P. N-acyl homoserine lactones AHL are small signal molecules involved in the quorum sensing of many gram-negative bacteria, and play an important role in biofilm formation and pathogenesis.

Present analytical methods for identification and quantification of AHL require time-consuming sample preparation steps and are hampered by the lack of appropriate standards. Employing small-scale synthesis protocols, we established a versatile and cost-efficient procedure for fast generation of isotope-labeled AHL standards, which can be used without extensive purification and yielded accurate standard curves.

Quantitative analysis was possible in the low pico-molar range, with lower limits of quantification reaching from 1 to 5 pmol for different AHL. Function and evolution of ubiquitous bacterial signaling adapter phosphopeptide recognition domain FHA. Forkhead-associated domain FHA is a phosphopeptide recognition domain embedded in some regulatory proteins. With similar fold type to important eukaryotic signaling molecules such as Smad2 and IRF3, the role of bacterial FHA domain is intensively pursued.

Reported bacterial FHA domain roles include: To provide basis for the studies of other bacterial FHA domain containing proteins, the status of bacterial FHA functionality and evolution were summarized. Published by Elsevier Inc. Bacterial cell-to-cell communication quorum sensing refers to the regulation of bacterial gene expression in response to changes in microbial population density.

Quorum sensing bacteria produce, release and respond to chemical signal molecules called autoinducers. Bacteria use two types of autoinducers, namely autoinducer-1 AI-1 and autoinducer-2 AI-2 where the former are N-acylhomoserine lactones and the latter is a product of the luxS gene.

Most of the reported literatures show that the majority of oral bacteria use AI-2 for quorum sensing but rarely the AI-1 system. Here we report the isolation of Pseudomonas putida strain T from the oral cavity.

This is the first report of the finding of quorum sensing of P. N-acyl homoserine lactone -producing Pseudomonas putida strain T from human tongue surface.

Quorum sensing inhibitory potential and molecular docking studies of sesquiterpene lactones from Vernonia blumeoides. The increasing incidence of multidrug-resistant Gram-negative bacterial pathogens has focused research on the suppression of bacterial virulence via quorum sensing inhibition strategies, rather than the conventional antimicrobial approach. The anti-virulence potential of eudesmanolide sesquiterpene lactones previously isolated from Vernonia blumeoides was assessed by inhibition of quorum sensing and in silico molecular docking.

Inhibition of quorum sensing-controlled violacein production in Chromobacterium violaceum was quantified using violacein inhibition assays. Qualitative modulation of quorum sensing activity and signal synthesis was investigated using agar diffusion double ring assays and C. Violacein inhibition was significant for the ethyl acetate extract with decreasing inhibition being observed with dichloromethane, hexane and methanol extracts. Agar diffusion double ring assays indicated that only the activity of the LuxI synthase homologue, CviI, was modulated by blumeoidolides A and B, and V.

Finally, molecular docking was conducted to explore the binding conformations of sesquiterpene lactones into the binding sites of quorum sensing regulator proteins, CviR and CviR'. The computed binding energy data suggested that the blumeoidolides have a tendency to inhibit both CviR and CviR' with varying binding affinities. Vernonia eudesmanolide sesquiterpene lactones have the potential to be novel therapeutic agents, which might be important in reducing virulence and pathogenicity of drug-resistant bacteria.

Sesquiterpene lactones from Staehelina fruticosa. The phytochemical analysis of Staehelina fruticosa led to the isolation of four germacranolide-type sesquiterpene lactones 1- 4 , including two new glycosides.

The structures of these sesquiterpene lactones were elucidated using spectroscopic techniques, and enzymatic hydrolysis was carried out to confirm the nature of the two glycoside derivatives.

Molecular modeling was incorporated to substantiate their relative configuration. Communication between bacteria, belonging to the same species or to different species, is mediated through different chemical signals that are synthesized and secreted by bacteria. These signals can either be cell-density related autoinducers or be produced by bacteria at different stages of growth, and they allow bacteria to monitor their environment and alter gene expression to derive a competitive advantage.

The properties of these signals and the response elicited by them are important in ensuring bacterial survival and propagation in natural environments e. First, the interaction between a signal and its receptor is very specific, which underlies intraspecies communication and quorum sensing. Second, when multiple signals are synthesized by the same bacterium, the signaling circuits utilized by the different signals are coordinately regulated with distinct overall circuit architecture so as to maximize the overall response.

Third, the recognition of a universal communication signal synthesized by different bacterial species interspecies communication , as well that of signals produced by eukaryotic cells interkingdom communication , is also integral to the formation of multispecies biofilm communities that are important in infection and disease.

The focus of this review is on the principles underlying signal -mediated bacterial communication, with specific emphasis on the potential for using them in two applications-development of synthetic biology modules and circuits, and the control of biofilm formation and infection. In gram-negative bacterial pathogens, such as Pseudomonas aeruginosa and Yersinia pseudotuberculosis, cell-to-cell communication via the N-acylhomoserine lactone AHL signal molecules is involved in the cell population density-dependent control of genes associated with virulence.

This phenomenon, termed quorum sensing, relies upon the accumulation of AHLs to a threshold concentration at which target structural genes are activated. By using biosensors capable of detecting a range of AHLs we observed that, in cultures of Y.

When added to late-stationary-phase, cell-free culture supernatants of the respective pathogen, the major P. Little AHL inactivation occurred with cell extracts, and no evidence for inactivation by specific enzymes was apparent.

This AHL turnover was discovered to be due to pH-dependent lactonolysis. By acidifying the growth media to pH 2. Results showed that these probiotic strains had no adverse effect on general health status, feed intake, body weight gain and intestinal mucosal morphology villus height, crypt depth, epithelial cell height and mucosal thickness.

No viable bacteria were recovered from blood and tissue samples mesenteric lymph nodes, liver and spleen of mice, and no treatment-associated illness or death was observed.

This suggests that the probiotic strains HN, HN and HN are non-pathogenic and likely to be safe for human consumption. Protective effect of potentially probiotic Lactobacillus strain on infection with pathogenic bacteria in chickens. The probiotic potential of a Lactobacillus salivarius 3d strain isolated from chicken faeces was assessed in one day old chickens. Lactobacillus salivarius 3d was administered per os at a concentration of 10 8 cfu in microl of PBS.

The chickens were then challenged with pathogenic bacteria: Salmonella Enteritidis, Campylobacter jejuni and Clostridium perfringens. Samples of caecal contents and livers were collected after 1, 2, 3, 7 and 14 days after infection. Lactobacilli and pathogenic bacterial cell counts were determined in the samples.

This study showed that L. Therefore it may be concluded that L. Survival and retention of the probiotic properties of Bacillus sp. The probiotic properties of Bacillus strains isolated from Artemia culture and the effect of marine stress on viability and survival were investigated, as well as the changes occurring in their properties.

Analyses showed that these bacteria corresponded to the genus Bacillus sp. Antagonism and adherence assays revealed that Bacillus strains have an inhibitory effect against tested pathogenic bacteria and are fairly adherent. Normal and starved cells showed different enzymatic profiles.

Challenge tests performed with Artemia larvae provided evidence that the tested Bacillus strains were neither pathogenic nor toxic to the host and conferred protection for Artemia culture against pathogens. The tested strains maintained their viability and their probiotic properties during the period of study.

The results suggest that the tested strains have suffered changes allowing them to survive in seawater in the absence of nutrients and outside their natural host, identifying them as potential probiotic candidates for Artemia culture. Probiotic potential of selected lactic acid bacteria strains isolated from Brazilian kefir grains. A total of 34 lactic acid bacteria isolates from 4 different Brazilian kefir grains were identified and characterized among a group of isolates, using the ability to tolerate acidic pH and resistance to bile salts as restrictive criteria for probiotic potential.

Eighteen isolates belonged to the species Leuconostoc mesenteroides, 11 to Lactococcus lactis of which 8 belonged to subspecies cremoris and 3 to subspecies lactis , and 5 to Lactobacillus paracasei. To exclude replicates, a molecular typing analysis was performed by combining repetitive extragenic palindromic-PCR and random amplification of polymorphic DNA techniques. All strains showed some antagonistic activity against 4 model food pathogens.

In addition, 3 Lc. None of these strains showed undesirable enzymatic or hemolytic activities, while proving susceptible or intrinsically resistant to a series of clinically relevant antibiotics. Taken together, these properties allow the MRS59 strain to be considered a promising probiotic candidate. Published by Elsevier Inc. Characterization of certain bacterial strains for potential use as starter or probiotic cultures in dairy products.

The present work was aimed at characterizing 12 strains of lactic acid bacteria LAB to obtain improved potential starter or probiotic cultures that could be used for making dairy products from ewe's milk and cow's milk. They were identified as Enterococcus faecalis five strains , Lactococcus lactis subsp. Additionally, four strains were obtained from the American Type Culture Collection: Lactobacillus casei isolated from cheese , L.

This last enzymatic activity was also lacking in L. Several strains could be considered promising probiotic candidates since they showed good growth capacity and survival under simulated gastro-intestinal conditions acidic pH of 1. Moreover, co-aggregation of lactobacilli with pathogenic bacteria was shown with Listeria innocua, Staphylococcus aureus, Escherichia coli, and Salmonella Enteritidis as good defense strategy against gut and food pathogens.

Furthermore, they exhibited adherence to intestinal and vaginal cell lines, such property could be reinforced by their capacity of biofilm formation which is also important in food matrices such as the olive surface. Their antagonistic activity against pathogenic bacteria by means of acids and plantaricins, and also their different functional properties may determine their efficacy not only in the gastro-intestinal tract but also in food matrices.

Besides their ability to ferment several prebiotics, the new evidence in the present study was their capacity to ferment lactose which reinforces their use in different food matrices including dairy as a dietary adjunct to improve lactose digestibility.

Lactobacillus pentosus CFN was selected to have the best probiotic profile being of great interest in further studies. Selection of potentially probiotic Lactobacillus strains towards their inhibitory activity against poultry enteropathogenic bacteria. Lactobacilli were isolated from chicken gastrointestinal tract and examined for their potentially probiotic properties towards their inhibitory activity against poultry enteropathogenic bacteria.

The identification of isolated Lactobacillus strains based on phenotypic properties was not always satisfactory. Lactobacilli were tested for the inhibitory activity against selected strains of poultry enteropathogenic bacteria Salmonella Enteritidis, Escherichia coli and Clostridium perfringens. Examined supernatants from Lactobacillus broth cultures demonstrated major antimicrobial activity against C.

Lower antimicrobial activity were observed against E. The strongest inhibition effect were obtained using supernatant of Lactobacillus acidophilus strain 3D. Results received from this study confirmed that identification of Lactobacillus spp. Some isolates, which are in vitro antagonistic against enteropathogenic bacteria may be considered as potential candidates for poultry probiotics , especially in controlling necrotic enteritis caused by C.

A Bacillus subtilis strain as probiotic in poultry: We have proposed and validate an in vitro probiotic selection, based on enzymatic potentialities associated to well-established probiotic functional properties.

A new Bacillus subtilis HB2 isolate, selected based on its high extracellular enzyme production, was chosen as a probiotic candidate for application as animal feed supplement.

The HB2 strain showed an excellent acid and bile salts tolerance, a strong adhesion to chick enterocytes and produced antimicrobials against pathogens. An in vivo trial in poultry farming was conducted to evaluate the HB2 probiotic performance. The mortality and the feed conversion ratio were significantly decreased. Finally, the HB2 treated group showed wet litter and less severe ammonia odor in the atmosphere.

Our study provides new insights into the importance of enzymatic potentialities , associated with the common functional properties, as a novel approach for probiotic selection. Evidence for probiotic potential of a capsular-producing Streptococcus thermophilus CHCC strain.

The purpose of this research was to evaluate the probiotic potential of an capsulated Streptococcus thermophilus CHCC strain. The strain tolerates 0. The strain demonstrated high adherence to human intestinal mucus, and showed unique resistance to different antibiotics. The bacteriocin was heat stable, resistant to pH, inactivated by proteolytic enzymes, and resistant to a-amylase and lipase.

The strain may have industrial significance and represents an interesting candidate for use in biopreservation, probiotic food formulations and in the control of spoilage caused by food borne pathogens. The aim of the study was to isolate and characterize the lactic acid bacteria LAB from animal manure. Biochemical and physiology properties of strains confirmed that the strains are related to the Lactobacillus sp. The strains exhibited susceptibility against commonly used antibiotics with negative hemolytic property.

Fermentation studies noted that the strains were able to produce significant amount of lactic, acetic, and succinic acids. Further, the production of extracellular proteolytic and glycolytic enzymes, survival under low pH, bile salts, and gastric juice together with positive bile salt hydrolase Bsh activity, cholesterol lowering, cell surface hydrophobicity, and aggregation properties were the strains advantages. In conclusion, novel L. Probiotic potential of lactobacillus strains isolated from sorghum-based traditional fermented food.

Sorghum-based traditional fermented food was screened for potential probiotic lactic acid bacteria. The isolates were identified by biochemical, physiological and genetic methods.

Species identification was done by 16s rRNA sequence analysis. The functional probiotic potential of the two Lactobacillus species viz. The strains were tolerant to pH 2 for 1 h and resistant to methicillin, kanamycin, vancomycin and norfloxacin. All the strains showed tolerance to artificial duodenum juice pH 2 for 3 h, positive for bile salt hydrolase test and negative for haemolytic test.

The neutralized cell-free supernatant of the strains Lact. The study also evaluated the cholesterol lowering property of the Lactobacillus strains using hen egg yolk as the cholesterol source. The cholesterol in hen egg yolk was assimilated by Probiotics as potential antioxidants: Probiotics are known for their health beneficial effects and are established as dietary adjuncts.

Probiotics have been known for many beneficial health effects. In this view, there is interest to find the potential probiotic strains that can exhibit antioxidant properties along with health benefits. In vitro and in vivo studies indicate that probiotics exhibit antioxidant potential. In this view, consumption of probiotics alone or foods supplemented with probiotics may reduce oxidative damage, free radical scavenging rate, and modification in activity of crucial antioxidative enzymes in human cells.

Incorporation of probiotics in foods can provide a good strategy to supply dietary antioxidants, but more studies are needed to standardize methods and evaluate antioxidant properties of probiotics before they can be recommended for antioxidant potential. In this paper, the literature related to known antioxidant potential of probiotics and proposing future perspectives to conduct such studies has been reviewed.

We report the draft genome sequence of Lactobacillus salivarius SMXD51, isolated from the cecum of healthy chickens showing an activity against Campylobacter—the food-borne pathogen that is the most common cause of gastroenteritis in the European Union EU —and potentially interesting features for a probiotic strain , explaining our interest in it.

Evaluation of potential probiotic characteristics and antibacterial effects of strains of Pediococcus species isolated from broiler chickens. A total of lactic acid bacteria were isolated and 51 isolates including 31 Lactobacillus spp.

The results showed the presence of two strains , Pediococcus acidilactici P17 and P19 in rectal swab samples from d old chickens with significant antibacterial activities against Salmonella enteritidis and Escherichia coli.

The results suggest that only a few isolates of Pediococcus with potential probiotic activities are present in the poultry industry. In vitro and in vivo survival and transit tolerance of potentially probiotic strains carried by artichokes in the gastrointestinal tract. The ability of potentially probiotic strains of Lactobacillus plantarum and Lactobacillus paracasei to survive on artichokes for at least 90 days was shown.

The anchorage of bacterial strains to artichokes improved their survival in simulated gastrointestinal digestion. Evaluation of the potential use of probiotic strain Lactobacillus plantarum v in lactic fermentation of button mushroom fruiting bodies. The available literature does not provide data on the application of probiotic strains in mushroom processing.

The aim of the study was to evaluate the potential to use the L. Fresh button mushroom fruiting bodies and cultures of lactic acid bacteria L. After a week-long lactic fermentation, the pH value in the samples declined to a level of 3. Fermented mushrooms were assigned high grades in the organoleptic evaluation. Blanching contributed to a significant decrease in the content of total phenolic compounds in the mushroom fruiting bodies and to a decline in antioxidant activity.

Mushrooms fermented with the probiotic strain were characterised by higher phenolic compound content and higher antioxidant activity. Products obtained with the use of both strains were characterised by good sensory properties. The type of strain used in the lactic fermentation of mushroom fruiting bodies had an effect on the phenolic compound content and antioxidant properties of the final product.

Potential probiotic Pichia kudriavzevii strains and their ability to enhance folate content of traditional cereal-based African fermented food. With the aim of selecting starter cultures with interesting probiotic potential and with the ability to produce folate in a food matrix, yeast strains isolated from fermented cereal-based African foods were investigated. A total of 93 yeast strains were screened for their tolerance to pH 2 and 0. Pichia kudriavzevii isolates gave the best results.

Moreover, presence of folate biosynthesis genes was verified and production of extra and intra-cellular folate determined during growth in culture medium. To be closer to traditional cereal-based fermentations, a P. The use of strains with both probiotic and nutritional enrichment properties may have a greater impact for the consumers. Characterization of some potentially probiotic Lactobacillus strains isolated from Iranian native chickens. The objective of the present study was to isolate, identify and characterize new LAB strains with high probiotic potentials from Iranian Isfahan indigenous chickens.

From 90 isolated LABs, 11 isolates had high growth rate under different stress conditions, including acid pH 2. Based on the molecular identification using 16S rDNA sequencing and phylogenetic analysis, the isolates belonged to two Lactobacillus salivarius and L.

The isolates showed different tolerance to 16 clinically and veterinary relevant antibiotics, and most of them were resistant to or semi-tolerant of different studied antibiotics. The Es11, Es12, Es3 and Es13 strains with resistance to or semi-tolerance of 15, 14 and 13 different antibiotics, respectively, were the most tolerant strains.

The selected isolates showed a wide range of antimicrobial activity against 7 different pathogenic strains. All the isolates exhibited antagonistic activity against E.

The isolates Es6 and Es11 with high antagonistic activity and resistance against 6 of the studied pathogens were the most powerful antagonistic isolates. Finally, based on all the experiments, 7 strains , including Es1, Es6, Es7, Es11, Es12 and Es13, were selected for the further in vivo assays and possible use in the poultry industry. A molecular method for efficient and accurate detection and identification of two potential probiotic lactobacilli strains isolated from fermented olives, namely Lactobacillus pentosus B and Lb.

The specificity of the assay was tested and successfully confirmed in 27 and 22 lactobacilli strains for Lb. Moreover, the two strains were used as starter cultures in yogurt production. Although the pH values of the novel products were slightly lower than the control ones, the yogurt containing the probiotic cultures scored similar values compared to the control in a series of sensory tests.

Overall, these results demonstrated the possible use of the two strains as starter adjuncts in the production of yogurt with potential probiotic properties. Saxami, Georgia; Papadopoulou, Olga S. Probiotic potential and biotherapeutic effects of newly isolated vaginal Lactobacillus acidophilus 36YL strain on cancer cells.

Lactobacillus acidophilus is categorized as a probiotic strain because of its beneficial effects in human health and prevention of disease transmission.

This study is aimed to characterize the probiotic potential of L. This newly isolated strain was found to exhibit notable probiotic properties, such as admirable antibiotic susceptibility, good antimicrobial activity, and favorable resistance to acid and bile salt.

The results of bioactivity assessment demonstrated acceptable anticancer effects on the four tested cancer cell lines and negligible side effects on the assayed normal cell line. Our findings revealed that the anticancer effect of L.

Isolation and in vitro selection of actinomycetes strains as potential probiotics for aquaculture. This study was designed to describe a series of in vitro tests that may aid the discovery of probiotic strains from actinomycetes. Actinomycetes were isolated from marine sediments using four different isolation media, followed by antimicrobial activity and toxicity assessment by the agar diffusion method and the hemolysis of human blood cells, respectively.

Extracellular enzymatic production was monitored by the hydrolysis of proteins, lipids and carbohydrates. Tolerance to different pH values and salt concentrations was also determined, followed by hydrophobicity analysis and genetic identification of the most promising strains. Five out of 31 isolated strains showed antimicrobial activity against three Vibrio species.

Three actinomycetes strains showing probiotic -like properties were discovered using several in vitro tests that can be easily implemented in different institutions around the world.

Nine wild Lactobacillus strains , namely Lactobacillus plantarum 53, Lactobacillus fermentum 56, L. Considering the safety aspects, the resistance to antibiotics varied among the examined strains , and none of the strains presented hemolytic and mucinolytic activity.

Regarding the physiological functionality properties, none of the strains were able to deconjugate bile salts; all of them presented low to moderate cell hydrophobicity and were able to autoaggregate, coaggregate with Listeria monocytogenes and Escherichia coli, and antagonize pathogenic bacteria. Exposure to pH 2 sharply decreased the survival of the examined strains after 1- or 2-h exposure; variable decreases were noted after 3-h exposure to pH 3. Overall, exposure to pH 5 and to bile salts 0.

Examined strains presented better ability to survive from the exposure to simulated gastrointestinal conditions in laboratorial media and milk than in grape juice. These results indicate that wild Lactobacillus strains isolated from fruit processing by-products could present performance compatible with probiotic properties and technological features that enable the development of probiotic foods with distinct characteristics.

Genome sequence analysis of potential probiotic strain Leuconostoc lactis EFEL isolated from kimchi. Leuconostoc lactis EFEL KACC isolated from kimchi showed promising probiotic attributes; resistance against acid and bile salts, absence of transferable genes for antibiotic resistance, broad utilization of prebiotics, and no hemolytic activity.

To expand our understanding of the species, we generated a draft genome sequence of the strain and analyzed its genomic features related to the aforementioned probiotic properties. Genomic analysis revealed the presence of various genes for sucrose metabolism glucansucrases, invertases, sucrose phosphorylases, and mannitol dehydrogenase , acid tolerance F1F0 ATPases, cation transport ATPase, branched-chain amino acid permease, and lysine decarboxylase , vancomycin response regulator, and antibacterial peptide Lactacin F.

No gene for production of biogenic amines histamine and tyramine was found. This report will facilitate the understanding of probiotic properties of this strain as a starter for fermented foods. Complete genome sequence of Lactobacillus helveticus CAUH18, a potential probiotic strain originated from koumiss. Here we report the complete genome sequence of Lactobacillus helveticus CAUH18, a new strain isolated from traditional fermented dairy product koumiss.

Its genome has a circular 2. The genome sequence indicated that this strain harbors a gene cluster involved in a novel exopolysaccharides EPS biosynthesis and a gene encoding cell-surface aggregation-promoting factors APFs to facilitate its colonization in gastrointestinal tract GIT.

This genome sequence provides a basis for further studies about its molecular genetics and probiotic functions. Bacillus cereus is an important cause of foodborne infectious disease and food poisoning. In this study, we evaluated the safety of 15 commercial probiotic B. Most preparations were incorrectly labeled, as they contained additional bacterial species; one product did not contain viable B. In total, 18 B.

Enterotoxin genes nhe, hbl, and cytK1, as well as the ces-gene were assessed by PCR. Enterotoxin production and cytotoxicity were confirmed by ELISA and cell culture assays, respectively. Antimicrobial resistance was assessed by microdilution; resistance genes were detected by PCR and further characterized by sequencing, transformation and conjugation assays.

Nearly half of the strains harbored the antimicrobial resistance gene tet In one strain , tet 45 was situated on a mobile genetic element-encoding a site-specific recombination mechanism-and was transferable to Staphylococcus aureus and Bacillus subtilis by electro-transformation. In view of the wide and uncontrolled use of these products, stricter regulations for safety assessment, including determination of virulence factors and transferable antimicrobial resistance genes, are urgently needed.

Isolation and characterization of a Bacillus amyloliquefaciens strain with zearalenone removal ability and its probiotic potential.

Zearalenone ZEN is a non-steroidal estrogenic mycotoxin produced by Fusarium species, which has been shown to be associated with reproductive disorders in livestock, and to a lesser extent with hyperoestrogenic syndromes in humans. The aim of this study was to characterize a Bacillus amyloliquefaciens strain with ZEN removal ability. A pure culture of a strain designated LN isolated from moldy corn samples showed a high ZEN removal capability.

Based on microscopic observations, biochemical characteristics, and phylogenetic analysis of the 16S rRNA gene sequence, LN was identified as B. After incubation of B. In ZEN-contaminated corn meal medium, B.

The amounts of ZEN adsorbed by the cells of B. These findings suggest that B. In one strain , tet 45 was situated on a mobile genetic element—encoding a site-specific recombination mechanism—and was transferable to Staphylococcus aureus and Bacillus subtilis by electro-transformation. The use of intestinal probiotic bacteria is very common in the food industry and has been the focus of the majority of research in this field.

Yet in recent years, research on extraintestinal microorganisms has greatly increased due to their well-known potential as probiotics. First, we examined the impact of pH on the growth of this strain and studied its survival under conditions similar to those of the human gastrointestinal tract. Next, we subjected L.

Lastly, we measured the susceptibility of this strain to numerous antibiotics and its tendency to autoaggregate. Overall, our findings support the potential use of this extraintestinal bacterium as a dietary probiotic. The selected lactobacilli include strains of Lactobacillus casei subsp. Although a wide variation in the ability of the eight strains to deplete cholesterol and nitrite, antagonize pathogens, scavenge free radical, and stimulate innate immune response were observed, the strains CICC and CGMCC 1.

Complete genome sequence of Lactobacillus plantarum LZ95, a potential probiotic strain producing bacteriocins and B-group vitamin riboflavin. Lactobacillus plantarum LZ95 is a potential probiotic isolated from newborn infant fecal and it is identified to produce riboflavin with great antimicrobial activity.

The complete genome sequence of this strain was reported in the present study. The genome contains a 3,,bp chromosome and two plasmids. Genes, related to the biosynthesis of bacteriocins and riboflavin, were identified. This work will facilitate to reveal the biosynthetic mechanism of bacteriocins and B-group vitamins in lactic acid bacteria and provide evidence for its potential application in food industry. Cheeses have been proposed as a good alternative to other fermented milk products for the delivery of probiotic bacteria to the consumer.

The effect of such strains on the volatile compounds profile, texture, and other sensorial properties, including an overall consumer acceptance, was also investigated. Globally, the addition of the L. A total of 59 volatile compounds were identified in the headspace of experimental cheeses, and some L. All cheeses presented good results of acceptance after the sensory evaluation. Consequently, our results indicated that fresh cheese can be a good vehicle for the two L.

Development of a potential probiotic fresh cheese using two Lactobacillus salivarius strains isolated from human milk. Two probiotic strains , Lactobacillus johnsonii x-1d-2 and Lactobacillus mucosae x-4w-1, originally isolated from piglet feces, have been demonstrated to possess antimicrobial activities, antibiotic resistances and interleukin-6 induction ability in RAW These characteristics make L. In this study, soybeal meal, molasses and sodium acetate were selected to optimize the growth medium for cultivation of L.

These two strains were then freeze-dried and mixed into the basal diet to feed the weaned piglets. The effects of L. The results showed that the bacterial numbers of L. In a further feeding study, the weaned piglets fed basal diet supplemented with freeze-dried probiotic cultures exhibited higher p Probiotic feeding also increased the numbers of lactobacilli and decreased the numbers of E.

This study demonstrates that L. A new strain of Bacillus coagulans CGMCC , which has a broad range of antibacterial activities against six main pathogenic bacteria including Escherichia coli O8, Staphylococcus aureus, Salmonella enterica subsp. In adhesion assay, the isolate exhibited a stronger adhesion to pig intestinal mucus than that of B. Additionally, the bacteria showed amylase, protease and cellulase activities.

The safety assessment demonstrated the lack of toxicity potential in B. These results implied that that the new strain of B.

Antibacterial activity and genotypic-phenotypic characteristics of bacteriocin-producing Bacillus subtilis KKU The antimicrobial activity and probiotic properties of Bacillus subtilis strain KKU, isolated from local soil, were investigated. The cell-free supernatant CFS of a KKU culture containing crude bacteriocins exhibited inhibitory effects on Gram-positive bacteria, including Bacillus cereus, Listeria monocytogenes, Micrococcus luteus, and Staphylococcus aureus.

However, proteins larger than 25 kDa and smaller than 10 kDa were still observed on a native protein gel. Its molecular mass was found to be 3. In addition to stable and cyclic subtilosin A, a mixture of many extracellular antibacterial peptides was also detected in the KKU culture. The KKU strain produced extracellular amylase, cellulase, lipase and protease, is highly acid-resistant pH 2 when cultured in inulin and promotes health and reduces infection of intestinally colonized broiler chickens.

Therefore, we propose that bacteriocin-producing B. The intestinal microbiota has an influence on the growth and health status of the hosts. This is of particular interest in animals reared using intensive farming practices. Hence, it is necessary to know more about complexity of the beneficial intestinal microbiota. The use of molecular methods has revolutionized microbial identification by improving its quality and effectiveness.

The specific aim of the study was to analyze predominant species of Lactobacillus in intestinal microbial ecosystem of young calves. Forty-two lactic acid bacteria LAB isolated from intestinal tract of young calves were characterized by: ARDRA screening revealed nine unique patterns among 42 isolates, with the same pattern for 29 of the isolates.

Gene fragments of 16S rDNA of 19 strains representing different patterns were sequenced to confirm the identification of these species. These results confirmed that ARDRA is a good tool for identification and discrimination of bacterial species isolated from complex ecosystem and between closely related groups. This paper provides information about the LAB species predominant in intestinal tract of young calves that could provide beneficial effects when administered as probiotic.

Complete genome sequence of Lactobacillus plantarum LZ, a potential probiotic strain producing B-group vitamins. B-group vitamins play an important role in human metabolism, whose deficiencies are associated with a variety of disorders and diseases. Certain microorganisms such as Lactic acid bacteria LAB have been shown to have capacities for B-group vitamin production and thus could potentially replace chemically synthesized vitamins for food fortification.

A potential probiotic strain named Lactobacillus plantarum LZ, which was isolated from raw cow milk in this study, exhibits the ability to produce B-group vitamins.

Complete genome sequencing of LZ was performed to gain insights into the genetic elements involved in B-group vitamin production. The genome of LZ contains a circular 3,,bp chromosome, three circular plasmids and two predicted linear plasmids.

LZ also contains gene clusters for biosynthesis of both riboflavin and folate. This genome sequence provides a basis for further elucidation of its molecular genetics and probiotic functions, and will facilitate its applications as starter cultures in food industry. The flagellin hypervariable region is a potential flagella display domain in probiotic Escherichia coli strain Nissle The most studied probiotic , Escherichia coli strain Nissle EcN possesses flagella of serotype H1.

To explore the potential to use EcN flagellin in flagella display applications, we investigated the effect of deleting amino acids in the hypervariable region of flagellin on EcNc EcN cured of its two cryptic plasmids pMUT1 and pMUT2.

Two EcNc flagellin isogenic mutants with deletions of amino acid residual from to and from to in the hypervariable domain were constructed. These hypervariable regions may have future utility in the display of heterologous epitopes. The present study evaluates the probiotic properties of three Lactobacillus plantarum strains MJM, MJM, and MJM possessing antimicrobial activity against animal enteric pathogens.

The three strains did not show bioamine production, mucinolytic and hemolytic activity and were susceptible to common antibiotics. The mechanism of antimicrobial activity of the L. Finally, the three L. These characteristics of the three L. Tailoring the probiotic potential of non-starter Lactobacillus strains from ripened Parmigiano Reggiano cheese by in vitro screening and principal component analysis.

Non-starter lactic acid bacteria NSLAB inhabiting fermented food have been recently revised as source of probiotic strains. Most strains showed moderate to good resistance to biological barriers, including bile salts, lysozyme, and simulated gastric and pancreatic juices.

Antimicrobial susceptibility tests against seven antimicrobials belonging to different categories showed that most strains are susceptible towards all the antibiotics, with the exception of vancomycin and streptomycin. The strains lost the streptomycin resistance when assayed on agar medium containing 0. No isolate showed bile salt hydrolase BSH activities, supporting that bile salts resistance and BSH activity are unpaired traits.

Finally, NSLAB strains had moderate to high auto-aggregative and hydrophobic phenotypes, whereas two subsets of 22 and 8 strains co-aggregated with Escherichia coli and Salmonella enterica s. A multivariate analysis was effective to segregate one L. Carbohydrate-binding specificities of potential probiotic Lactobacillus strains in porcine jejunal IPEC-J2 cells and porcine mucin. Bacterial lectins are carbohydrate-binding adhesins that recognize glycoreceptors in the gut mucus and epithelium of hosts.

In this study, the contribution of lectin-like activities to adhesion of Lactobacillus mucosae LM1 and Lactobacillus johnsonii PF01, which were isolated from swine intestine, were compared to those of the commercial probiotic Lactobacillus rhamnosus GG. Both LM1 and PF01 strains have been reported to have good adhesion ability to crude intestinal mucus of pigs.

To confirm this, we quantified their adhesion to porcine gastric mucin and intestinal porcine enterocytes isolated from the jejunum of piglets IPEC-J2. In addition, we examined their carbohydrate-binding specificities by suspending bacterial cells in carbohydrate solutions prior to adhesion assays. In addition, compared to adhesion to IPEC-J2 cells, adhesion to mucin by both LM1 and LGG was characterized by enhanced specific recognition of glycoreceptor components such as galactose, mannose, and N-acetylglucosamine.

Hydrophobic interactions might make a greater contribution to adhesion of PF A similar adhesin profile between a probiotic and a pathogen, suggest a correlation between shared pathogen- probiotic glycoreceptor recognition and the ability to exclude enteropathogens such as Escherichia coli K88 and Salmonella Typhimurium KCCM These findings extend our understanding of the mechanisms of the intestinal adhesion and pathogen-inhibition abilities of probiotic Lactobacillus strains.

Probiotic potentials of cereal-based beverages. Probiotics offer remarkable potential for the prevention and management of various infective and noninfective disorders.

They are reported to play key roles in the suppression of gastrointestinal infections, antimicrobial activity, improvement in lactose metabolism, reduction in serum cholesterol, immune system stimulation, antimutagenic properties, anticarcinogenic properties, anti-diarrheal properties, and improvement in inflammatory bowel disease. Although probiotic foods are classically confined to beverages and cheese, containing live organisms of the lactic acid bacteria family, such health-promoting foods are traditionally dairy-based, comprising milk and its fermented products.

However, recent research focuses on the probiotic potentials of fermented cereal-based beverages which are especially consumed in developing countries characterized by low nutritional security and high incidence of gut pathogen infections. Moreover, lactose intolerance and cholesterol content associated with dairy products, coupled with the vegetarian tendencies of diverse populations in the third world, tend to enforce the recent recourse to nondairy beverages.

Probiotic microorganisms are mostly of human or animal origin; however, strains recognized as probiotics are also found in nondairy fermented substrates. This review examines the potentials of some traditional cereal-based beverages to serve as probiotic foods, their microbial and functional properties, as well as their process optimization and storage for enhanced utilization.

Potential of goat probiotic to bind mutagens. The oral administration of these probiotics reduced fecal mutagens and intestinal cancer markers in goats. The capacity to bind benzopyrene and the stability of the bacterial-mutagen complex was analyzed by HPLC. The dismutagenic potential against both mutagens was proportional to probiotic concentration.

The mixture of four goat probiotics MGP displayed higher antimutagenic activity against SA than any individual strains at the same cell concentration. The stability of the toxic compounds-bacterial cell binding is a key consideration when probiotic antimutagenic property is evaluated. MGP exhibits the ability to bind and detoxify potent mutagens, and this property can be useful in supplemented foods for goats since it can lead to the removal of potent mutagens and protect and enhance ruminal health and hence food safety of consumers.

Isolation of lactic acid bacteria from swine milk and characterization of potential probiotic strains with antagonistic effects against swine-associated gastrointestinal pathogens. Probiotics are usually isolated from the gastrointestinal tract of humans and animals. The search of probiotics in human milk is a recent field of research, as the existence of the human milk microbiome was discovered only about a decade ago.

To our knowledge, no reports regarding the potential probiotic effect of bacteria from swine milk have been published. In this work, we isolated several lactic acid bacteria from swine milk and evaluated them for them potential as probiotics. Among the isolated strains , Lactobacillus curvatus TUCO-5E showed antagonistic effects against swine-associated gastrointestinal pathogens. TUCO-5E was able to reduce the growth of enterotoxigenic and enterohemorrhagic Escherichia coli strains as well as pathogenic salmonella.

In vitro exclusion and displacement assays in intestinal epithelial cells showed a remarkable antagonistic effect for L. Moreover, by using a mouse model of Salmonella infection, we were able to demonstrate that preventative administration of L. Therefore, we have demonstrated here that swine milk is an interesting source of beneficial bacteria.

In addition, the results of this work suggest that L. Species belonging to Lactobacillus genus were the predominant LAB in all fruit pulp processing byproducts. Further, five selected Lactobacillus strains L. The exposure to pH 2. Overall, the exposure to pH 5. All tested Lactobacillus strains presented inhibitory activity against Staphylococcus aureus, Salmonella Typhimurium, Salmonella Enteritidis, Listeria monocytogenes and Escherichia coli, and presented variable susceptibility to different antibiotics.

The selected Lactobacillus strains presented satisfactory and reproducible growth behavior. Determining the probiotic potential of cholesterol-reducing Lactobacillus and Weissella strains isolated from gherkins fermented cucumber and south Indian fermented koozh.

This study sought to evaluate the probiotic potential of lactic acid bacteria LAB isolated from traditionally fermented south Indian koozh and gherkin cucumber.

A total of 51 LAB strains were isolated, among which four were identified as Lactobacillus spp. The strains were screened for their probiotic potential. All isolated Lactobacillus and Weissella strains were capable of surviving under low pH and bile salt conditions. All LAB strains exhibited inhibitory activity against tested pathogens and were able to deconjugate bile salt. Exopolysaccharide production of LAB strains ranged from Potential of Zimbabwean commercial probiotic products and strains of Lactobacillus plantarum as prophylaxis and therapy against diarrhoea caused by Escherichia coli in children.

To evaluate the potential of commercial fermented products sold in the country, and strains of Lactobacillus plantarum L. Three commercial paediatric antidiarrhoeal drug products: An agar diffusion assay and a competitive exclusion assay were carried out on Mueller Hinton agar.

Crude cultures of putative lactobacillus strains obtained from Zimbabwean dairy products Probrand sour milk, Kefalos Vuka vuka cheese and Chibuku opaque beer had significantly higher antimicrobial activities against clinical strains of E. Studies to characterise the probiotic potential of the live cultures in the products and the new strains of L. Potential Uses of Probiotics in Clinical Practice.

Probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. There is now mounting evidence that selected probiotic strains can provide health benefits to their human hosts. Numerous clinical trials show that certain strains can improve the outcome of intestinal infections by reducing the duration of diarrhea. Further investigations have shown benefits in reducing the recurrence of urogenital infections in women, while promising studies in cancer and allergies require research into the mechanisms of activity for particular strains and better-designed trials.

At present, only a small percentage of physicians either know of probiotics or understand their potential applicability to patient care.

Thus, probiotics are not yet part of the clinical arsenal for prevention and treatment of disease or maintenance of health. The establishment of accepted standards and guidelines, proposed by the Food and Agriculture Organization of the United Nations and the World Health Organization, represents a key step in ensuring that reliable products with suitable, informative health claims become available. Based upon the evidence to date, future advances with single- and multiple- strain therapies are on the horizon for the management of a number of debilitating and even fatal conditions.

The strain BDU3 was identified as Bacillus coagulans by phenotypic and genotypic characterization. The BDU3 produced novel bacteriocin, which showed an antimicrobial spectrum toward a wide spectrum of food borne, and closely related pathogens with a MIC that ranged between 0.

The isolate was able to tolerate pH as low as 2. Three step purification was employed to increase the specific activity of the antimicrobial compound. Molecular mass of purified bacteriocin was found to be 1. The functional group was revealed by FTIR analysis. This is the smaller bacteriocin ever reported before from B.

This bacteriocin raises the possibilities to be used as a biopreservative in food industries. Performance of two potential probiotic Lactobacillus strains from the olive microbiota as starters in the fermentation of heat shocked green olives. The performance of two potential probiotic Lactobacillus strains from olive microbiota, namely L. A spontaneous fermentation was also taken into account as control treatment.

Microbiological, physicochemical and sensory analyses were conducted throughout fermentation. The final population of LAB was maintained above 6 log cycles in olive flesh. The sensory assessment showed higher preference for inoculated fermentations of L. The present study showed that probiotic strains L. Probiotic and technological properties of Lactobacillus spp. This work characterizes a set of lactobacilli strains isolated from the stomach of healthy humans that might serve as probiotic cultures.

Ten different strains were recognized by rep-PCR and PFGE fingerprinting among 19 isolates from gastric biopsies and stomach juice samples. These strains belonged to five species, Lactobacillus gasseri 3 , Lactobacillus reuteri 2 , Lactobacillus vaginalis 2 , Lactobacillus fermentum 2 and Lactobacillus casei 1.

All ten strains were subjected to a series of in vitro tests to assess their functional and technological properties, including acid resistance, bile tolerance, adhesion to epithelial gastric cells, production of antimicrobial compounds, inhibition of Helicobacter pylori, antioxidative activity, antibiotic resistance, carbohydrate fermentation, glycosidic activities, and ability to grow in milk.

As expected, given their origin, all strains showed good resistance to low pH 3. Species- and strain -specific differences were detected in terms of the production of antimicrobials, antagonistic effects toward H. None of the strains showed atypical resistance to a series of 16 antibiotics of clinical and veterinary importance. Probiotic attributes of autochthonous Lactobacillus rhamnosus strains of human origin.

The study was aimed at evaluating the probiotic potential of indigenous autochthonous Lactobacillus rhamnosus strains isolated from infant feces and vaginal mucosa of healthy female. The survival of the selected strains and the two reference strains L. The cell surface of L. The strains are neither haemolytic nor producer of biogenic amines such as histamine, putrescine, cadaverine and tyramine.

Lyophilized cells of L. Decrease in lactobacilli in the intestinal microbiota of celiac children with a gluten-free diet, and selection of potentially probiotic strains. The intestinal microbiota would be implicated in pathology associated with celiac disease caused by an abnormal immune system reaction against gluten present in cereal grains. Results demonstrated that the feces of celiac children with a gluten-free diet showed significantly lower counts of Lb P strains were selected because of their high resistance percentages to gastrointestinal tract conditions.

In addition, their autoaggregation and hydrophobicity properties were evaluated: Lactobacillus rhamnosus LC4 showed the highest percentage of autoaggregation while Lactobacillus paracasei LC9 showed high hydrophobicity.

Based on these results, LC4 and LC9 were selected, and their use as potential probiotic strains to improve signs and symptoms associated with celiac disease is discussed.

This is the first study performed in Argentina concerning the relationship between intestinal microbiota and celiac disease in celiac children with a gluten-free diet. In addition, the development of a probiotic food addressed towards celiac patients and designed with Lb isolated from the feces of healthy children from our province represents a promising alternative to improve the quality of life of celiac patients. Effect of chestnut extract and chestnut fiber on viability of potential probiotic Lactobacillus strains under gastrointestinal tract conditions.

The main challenge to probiotics , during their passage through the gastrointestinal tract, are the acidic gastric secretions of the stomach, and the bile salts released into the duodenum. The survival of the strains , in this phase, is strongly influenced by the food used for their delivery.

This work is part of a project studying the development of novel food processes, based on the use of chestnuts from cultivar "Castagna di Montella". In detail, the effect of indigestible chestnut fiber and of chestnut extract on the viability of selected lactic acid bacteria strains was evaluated.

Among 28 cultures, twelve strains were selected, on the basis of tolerance to low pH values and bile salts, and submitted to exposition to simulated gastric or bile juice in presence of chestnut extract with or without immobilization in chestnut fiber.

The presence of chestnut extract proved to play a significant role on the gastric tolerance improvement of lactobacilli. The recorded protective effect could not be simply related to the starch or reducing sugars content. RP-HPLC demonstrated that in the chestnut flour, there are one or more hydrophobic peptides or oligopeptides, which specifically offer a marked resistance to simulated gastric juice, albeit present at low concentration.

These beneficial effects proved to be dependent by the cultivar used to produce the flour. Antibiotic susceptibility of probiotic strains: Is it reasonable to combine probiotics with antibiotics? The main goal of this study was to determine the in vitro susceptibility of strains collected from marketed probiotics to antibiotics used to treat community-acquired infections.

The minimum inhibitory concentrations MICs of 16 antibiotics were determined using a gradient strip E test or the agar dilution method for fidaxomicin.

The probiotics demonstrated various antibiotic patterns. Bacterial probiotics are generally susceptible to most prescribed antibiotics orally administered, whereas yeast probiotics , such as Saccharomyces boulardii, are resistant. Special attention must be paid to co-prescriptions of antibiotics and probiotics to ensure that the probiotic strain is not susceptible.

Complete genome sequence of Lactobacillus plantarum LZ, a potential probiotic strain with antimicrobial activity against food-borne pathogenic microorganisms. Lactobacilli strains have been considered as important candidates for manufacturing "natural food", due to their antimicrobial properties and generally regarded as safe GRAS status.

Lactobacillus plantarum LZ is a potential probiotic strain isolated from raw cow milk, with antimicrobial activity against various pathogens, including Gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes , Gram-negtive bacteria Escherichia coli and Salmonella enterica , and fungus Candida albicans.

To better understand molecular base for its antimicrobial activity, entire genome of LZ was sequenced. It was revealed that genome of LZ contained a circular 3,,bp chromosome, two circular plasmids and one predicted linear plasmid.

A plantaricin gene cluster, which is responsible for bacteriocins biosynthesis and could be associated with its broad-spectrum antimicrobial activity, was identified based on comparative genomic analysis. Whole genome sequencing of L. Comparison of procedures for the extraction of supernatants and cytotoxicity tests in Vero cells, applied to assess the toxigenic potential of Bacillus spp. Interest in using Bacillus strains as probiotic components of animal feeds has grown in recent years.

However, some of these strains , especially those taxonomically related to the Bacillus cereus group, may have enterotoxigenic activity. Assessment of their toxigenic potential by well-established and robust protocols is required before authorizing their use in animal nutrition.


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Virulence factors of salmonella ser. enteritidis strains isolated in Italy The strains did not produce the hydroxamate-type siderophore aerobactin or the specific. Salmochelins, siderophores of Salmonella enterica and uropathogenic Escherichia colistrains, are recognized by the outer membrane receptor IroN. what are virulence factors for Salmonella? Enterotoxins LPS Siderophores S. Typhimurium, S. Newport, diarioimagen.infotidis, diarioimagen.infoberg.

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