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    13 Jun These bacteria keep their activities with plasma membrane proton pump in their cytoplasmic membrane HCN (28%), siderophore (21%), and soluble phosphorous (34%).Isolates showed plant .. cells as a function of sodium chloride by Kitada and Horikoshi () showed that the presence of sodium. The relationship between ligand and binding partner is a function of charge, hydrophobicity, and molecular structure. The instance of binding occurs In adults, fetal hemoglobin production can be reactivated pharmacologically, which is useful in the treatment of diseases such as sickle-cell disease. Overview The oxygen. 5 Sep Those nutrients will, for a large part, consist of carbohydrates associated with the cell wall and DNA of the target cell, known to be important for bacterial (including LAB) survival [81,82] during the stationary growth phase [83]. Indeed, this role for bacteriocin-producing LAB has been suggested previously as.
  3. Both this theory and the negative frequency-dependent theory suggest that that cheating exists as part of a stable mixed evolutionary strategy with mutualism. In other words, cheating is a stable strategy used by individuals in a population where many other individuals cooperate. Another study supports that cheating can.:

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On examination his neck is mildly stiff. Gram stain of the patient's CSF reveals neutrophils and numerous Gram-negative cocci, many in pairs. Which organism below is most likely? During surgery foul-smelling purulent material is aspirated from the infected area. Gram stain of this material contains a mixture of Gram positive cocci, Gram-positive rods, and many Gram-negative rods.

Aerobic culture on sheep blood agar yields many colonies of enterococci and a few colonies of E. Which organism is most likely to represent the majority of the Gram-negative rods seen when peritoneal exudate was stained? A woman with neurological illness. A few hours later she develops difficulty speaking, bilateral weakness of her arms, nausea, vomiting, dizziness, blurred vision, and dry mouth.

However she is alert, oriented, and has no fever. If this is botulism, by what mechanism did Clostridium botulinum produce her signs and symptoms? Bound to Toll-like receptors and stimulated production of inflammatory cytokines.

Injected proteins into neurons via a type III secretion system. Secreted a protein toxin that enters mammalian neurons and blocks synaptic transmission. Released peptidoglycan and other inflammatory components of the cell envelope. Bacteremic spread followed by infection of multiple tissues: What property of C. Produces airborne spores not easily killed by boiling. Vegetative cells grow best at cooking temperatures.

Extremely resistant to gastric acid. Thick peptidoglycan renders cells resistant to heat, cold, and drying. Surface proteins inhibit digestive hydrolases. A year-old man has high fever and elevated white count. Blood cultures are obtained. He is treated with a broad spectrum cephalosporin plus an aminoglycoside. The next day the laboratory reports that cultures contain catalase positive Gram-positive cocci in clusters.

Identification of the organism and determination of antibiotic sensitivity are underway. Pending arrival of these results, the cephalosporin is replaced with vancomycin.

Cephalosporins as a class have a narrower spectrum of action than vancomycin. The lab results suggest staphylococci, many of which are resistant to cephalosporins. Lysis of bacteria by cephalosporins may result in a massive inflammatory reaction. Vancomycin is a bactericidal antibiotic whereas cephalosporins are only bacteriostatic. The organism is identified as Staphylococcus aureus. Antibiotic sensitivity testing results are as follows: Small non-conjugative plasmid that encodes a penicillinase.

There is no D-ala-D-ala in the side chains of peptidoglycan. No peptidoglycan is present in the cell wall. Methylation of ribosomal RNA.

Cross-linking of peptidoglycan chains by transpeptidases. Enzymatic activity of dihydrofolate reductase. Peptide bond formation by bacterial ribosomes. It is 10 cm in diameter and ulcerated. Surrounding tissue is red and markedly swollen. The ulcer is healing to produce a black scab. A swab of the ulcer contains large Gram-positive rods. Soon afterwards, he becomes ill. He reports a 5-day history of fever, malaise, and headache.

Lesions are cm in diameter, oval with somewhat irregular outlines, with cm red borders and cm central red areas, separated by a belt of paler skin. Which diagnosis is most likely? The patient has a cat and reports that a few days ago the wretched ungrateful creature bit her on the right hand.

What pathogen is most strongly suggested by the history? A young woman with an abscess. A year-old female college student went to the Student Health Service because of fever, myalgia, and a five-cm abscess: This was lanced, drained, and disinfected. She was given antibiotics and acetaminophen Tylenol.

Late that day her roommate found her disoriented and took her to the Emergency Room. Her blood pressure was below normal and her pulse elevated. She showed no signs of meningitis but was lethargic and reported severe muscle aches. The next morning she was still hypotensive and showed signs of liver jaundice and kidney poor urine output dysfunction. Blood levels of liver and muscle enzymes were elevated. The preliminary diagnosis was Toxic Shock Syndrome.

Bacteria infected these sites by gaining access to the bloodstream from the abscess. A bacterial exotoxin acted on the central nervous system; organ damage was a secondary result.

Lipopolysaccharide released from dying bacteria caused monocytes to produce inflammatory cytokines. A bacterial exotoxin stimulated production of toxic levels of inflammatory cytokines by T cells. Bacteria bound to plasma membrane receptors of nerve, muscle, and kidney, and induced apoptosis. Dilation of small blood vessels. Increase in permeability of small blood vessels. Increased responsiveness of local sensory nerve endings. Infiltration of tissue by inflammatory cells. Two hours later he arrives at the Emergency Room with a red, swollen wrist and a fever of 40oC.

What process would you expect to have been most effective in producing his fever? Binding of O-antigen by IgG antibodies. Binding of Toll-like Receptors by Lipid A. Binding of magnesium ions by core polysaccharide. Binding of porin proteins by siderophores. MRI imaging demonstrated inflammation of the T8-T9 vertebral bodies consistent with osteomyelitis. A bone marrow biopsy, when cultured, produced colonies of Gram-positive cocci.

Colonies on Sheep blood agar were mm in diameter, off-white and beta-hemolytic. Colonies on Brain-heart infusion BHI agar were mm in diameter and golden yellow. Catalase and coagulase tests were positive. What is the most likely pathogen? The filaments were also weakly acid-fast. The organisms grew in aerobic culture.

Isolates from all cases are of serotype O A Gram-stained smear of exudate contains abundant neutrophils and slender Gram-negative rods. A sample is sent for culture and he is treated with a broad-spectrum antibiotic. The Gram-negative rod grows on Chocolate agar but not on standard Sheep blood agar when plates are cultured in room air. Which of the following organisms is most likely? Isolates which produce less-serious disease usually lack capsules.

Infection with non-encapsulated isolates results in protective immunity to them. The antibodies usually bind to bacterial surface proteins. In the genesis of these protective antibodies, which of the following is essential? Neutrophils process and present bacterial antigen to T cells.

Dendritic cells phagocytose and digest bacterial proteins. A year-old college student with no significant previous illness comes to see you after a trip to Mexico. On his third day in Cancun he developed watery diarrhea which lasted two days. He had avoided salads and un-bottled water but drank iced soft drinks from a stand on the beach.

He did not see a physician or take antibiotics. After returning he is well for about three weeks but again develops diarrhea, this time bloody. He reports pain on passage of stool, which is black and tarry. A stained smear of stool reveals many red and white cells, amoeboid forms which contain ingested erythrocytes, and cyst forms. Endoscopy reveals ulcerations of his colonic mucosa. He is started on an appropriate drug but two days later develops fever and septicemia, likely produced by spread of intestinal flora to the bloodstream from the ulcers in his colon.

He is treated with a combination of broad-spectrum antibiotics and makes a full recovery. About a month later, he develops a second episode of bloody diarrhea. This time, no amoeboid forms can be seen in stool smears. Culture on appropriate media for bacterial pathogens is also negative. Answer each question from the list of organisms below them. A young woman with white lesions on her oral mucosa. A smear of a scraping from a lesion contains budding yeast and pseudohyphae. Culture grows out creamy white colonies of budding yeast.

When yeast cells are suspended in plasma, buds elongate to form the beginnings of hyphae. Which fungus is most likely in this setting? Which phrase best describes these forms?

Mixture of mold and yeast forms. Hyphae, arthroconidia, and microconidia. Hyphae, rhizoids, and sporangia. Hyphae, basidia, and chains of conidia.

Hyphae, microconidia, and chlamydospores. A young boy with repeated bacterial infections. A 8-month-old boy has a middle ear infection. Exudate contains Gram-positive cocci, many in pairs. Local lymph nodes and tonsils are barely visible; you would have expected both to be swollen. His medical history includes numerous similar infections caused by non-encapsulated Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis, a Gram-negative coccus; pneumonia at 5 months, for which he was hospitalized; and a staphylococcal skin infection, which responded poorly to antibiotics, at 6 months.

Blood cultures from the pneumonia grew Streptococcus pneumoniae. Family history reveals a male cousin who died at age 14 months from pneumonia. IgE, mast cells, and basophils. What is the most likely reason that he did not develop infections before the age of five months? Babies of that age range are not exposed to bacteria. Maternal IgG provided protection. During the first few months of life the phagocytic capacity of neutrophils is high, but then declines. Factors H and I are not produced during the first six months of life, so that Complement is more active then than later.

Chest x-ray shows widespread diffuse inflammation of the lungs. She is given a prescription of an erythromycin-class drug, because a common bacterial cause of this type of illness in college students is resistant to all beta-lactam antibiotics. Which organism below best fits this description? Which of the following is most likely to account for the difference? Type of porin proteins in the outer membrane.

Presence or absence of common pili. Type of teichoic acid present. Isolates that lack capsules are much less virulent. How do capsules facilitate development of invasive disease?

Toxic to antibody-producing plasma cells. Block transport of protein antigens to lymph nodes. Prevent phagocytosis by neutrophils. Inhibit cytokine production by Helper T cells. Bind IgG and prevents activation of complement.

A critical difference to the siderophore system is that the resource the sensitive target cells might mutate into competitors resistant target cells. The fraction of resources that vanish in this way can also be assumed to depend on the scale of competition being less the more global the social arena is. The importance of scale might however be diminished if more than one type of bacteriocin is produced. The first multiple bacteriocin-producing LAB described was a strain of Lactococcus lactis that produced several lactococcins [ 92 , 93 ], with a very narrow inhibition spectrum [ 62 ].

Shortly afterwards, multiple bacteriocin production was also discovered in Carnobacterium maltaromaticum [ 56 , 94 , 95 ]. The inhibition spectrum of the carnobacteriocins B1, BM1 and B2 is wider than that of the lactococcins A, B and M see the electronic supplementary material, table S1 and might reflect the type of niche carnobacteria reside in [ 19 ].

Other LAB that produce multiple bacteriocins have subsequently also been found in lactobacilli e. Lactobacillus plantarum [ 96 ] and Lactobacillus sakei [ 97 ] , leuconostocs e. Leuconostoc mesenteroides [ 98 ] and enterococci e. Enterococcus faecium , [ 43 , 99 — ]. The potential synergy effect by producing multiple bacteriocins probably diminishes the possibility for selection of resistant variants.

Such bacteria that could be considered as cheaters include a variety of Gram-positive lineages as well as Gram-negative bacteria, in general. However, Gram-positive tolerant lineages might be selected against if the scale of competition is global as described earlier, whereas Gram-negative bacteria are selected against owing to their increased sensitivity towards organic acids produced by LAB [ , ].

Because the LAB bacteriocin producers are likely to meet ever-changing lineages of target cells in successive bottleneck situations, the model requires that the LAB bacteriocins exhibit relative broad target spectra in order to improve fitness of the producing cells.

Indeed, several LAB bacteriocins exhibit such broad spectra towards target species that may be only remotely phylogenetically related, i. Thus, a survey of the literature showed that among selected class I bacteriocins, all 10 showed inhibition against genera other than that to which the producer organism belonged, and this was also the case for 25 out of 30 class II bacteriocins see the electronic supplementary material, table S1.

There is, however, frequently intraspecific variation in bacteriocin susceptibility among target cells [ 97 , — ], which result in the likelihood of the presence of tolerant lineages in mixed culture batch fermentations.

The mechanism that confers resistance or tolerance to target cells is, in some instances, owing to differences in the membrane composition [ , , ], but other mechanisms e. There are indications that resistance phenotypes are associated with fitness costs [ , ]. As mentioned previously, bacteriocin-producing LAB contains an immunity gene s that confers resistance towards own bacteriocin s.

In a few cases putative orphan , immunity genes without any clear bacteriocin partner have been reported [ 94 , , ]. The mechanisms for maintaining the presence of such genes in LAB populations will require additional studies, but their occurrence might be explained by the Black Queen hypothesis BQH proposed by Morris et al. We propose that the lack of fitness cost of bacteriocin production is not of overall importance in an IGP model but this devaluates the usefulness of the rock—paper—scissor model for LAB bacteriocins.

Another way to reduce the fitness cost of bacteriocin production is to assess whether the bacteriocin has moonlighting properties [ ], meaning that it serves cellular functions other than interbacterial warfare.

An example is LAB bacteriocins that can also act as signal molecules in a quorum-sensing context [ 23 , 32 , 34 , 35 ]. Also, some bacteriocin-related molecules may exert biological roles unrelated to antagonism [ 31 , 33 , , ].

On the other hand, evidence exists that points towards additional cost of LAB bacteriocin production as LAB loci frequently contain numerous genes involved in bacteriocin production, immunity and secretion [ 19 , 23 — 27 , 34 , 35 , 44 , , ]. However, it should be noted that in the context of bottlenecks in batch fermentations, it is more relevant to study the presence of fitness costs associated with survival. Selfishness, as a social interaction, appears to be promoted by bacteriocin-producing LAB in batch culture habitats that allow for IGP.

Contrarily, the production of colicins has been extensively used as a convenient microbial model for the social interaction spite [ 89 , ].

The LAB bacteriocin systems described here may also be perceived, to some degree, as an example of altruism rather than of selfishness when tolerant or resistant lineages in addition to sensitive target cells are present in the environment of the producer. This combination of potentially two types of social interactions makes LAB bacteriocins an interesting model to explore.

This concerns the fact that in many complex microbial communities, the majority of species loose genes necessary for providing leaky common goods when this instead can be provided by a few key species, the black queens. As bacteriocin producers consume metabolites provided by sensitive strains, at least in theory, the producers may lose genes necessary for metabolizing specific substrates e.

In this analogy, IGPrey may, to some extent, resemble black queens with the difference that there most likely are more than just a few such lineages present in a typical LAB batch environment.

It would be of interest to examine whether bacteriocin producers may in fact carry fewer genes for metabolizing, for instance, specific carbohydrates than is the case for IGPrey lineages. Staying in the cards game analogy, one could compare LAB bacteriocin production to the game of Casino.

One aim is here to capture as many cards as possible equivalent to nutrients from a layout. However, one can only obtain cards bacteriocin sensitive cells that match the cards of the players' hand bacteriocin producers.

Selfishness has, compared with altruism and spite, received little recent attention in microbial models. However, this type of social behaviour is suitable for exploring general ecological interactions such as IGP, which is a very common phenomenon in nature [ 37 , ]. Microbial examples have primarily focused on ciliates acting as predator and intraguild prey, whereas bacteria provided the common resource [ 39 , ]. There are few reports, if any, on IGP including only bacteria, but it has to be kept in mind that the example offered here does not include a genuine IGP mechanism as the general resource for the IGPredator and IGPrey is nutrients from decaying organic material and thus not a prey organism as such.

Still, the LAB bacteriocin mechanism offers a model that might be useful for examination of more general aspects of IGP, such as the relationship between IGP and resource competition. It has been shown theoretically [ ] and experimentally, using ciliates and bacteria [ 39 ], that nutrient-rich environments allows predominance of the IGPredator. This is similar to the population dynamics predicted and observed for colicin producers [ 5 , 7 , 10 , ].

Indeed, the induction of bacteriocins in the late exponential or stationary growth phase by quorum sensing appears to present just such a polymorphism. An example could be the Streptomyces genus, which produces the majority of the natural antibiotics known to man. The genus is primarily found in the soil where it gets nutrition from decaying vegetation [ ]. The habitat is thus expected to create a bottleneck situation as has been discussed for LAB in this review. Interestingly, like LAB bacteriocin production, antibiotic production in Streptomyces is not initiated before entering the stationary phase, where growth rate slows down and production of aerial mycelium begins [ ].

Both protection against other microbes and recycling of killed sensitive cells have been proposed [ ] as an explanation for this timing of antibiotic production. The induction of antibiotic production upon nutrient exhaustion bottleneck coinciding with the production of aerial mycelium dispersion fits very well into the IGP model presented here and it would be of interest to examine experimentally whether this model could be used to explain Streptomyces antibiotic production.

We have until now only discussed fitness of LAB bacteriocin producers during population bottlenecks in environments where they have experienced a previous logarithmic phase of growth. We have described the dispersion to new potential habitats only as a parameter to adjust the scale of competition with a high degree of dispersion leading to a global scale of competition.

Even so, it can be anticipated that IGP is an important component of the social behaviour of bacteriocin-producing LAB. Future studies should test the validity of this mechanism on both a mathematical and an empirical level.

Such studies would quantify the magnitude of selection for bacteriocin producers under different bottleneck scenarios using microcosm evolution experiments. This would also illuminate the effects of habitats on the selection of types of social interactions. In this regard, it should be considered that bottleneck scenarios may promote other survival strategies in addition to bacteriocin production, with the phenomenon of persister cells as an example [ ].

The strength of the IGP model proposed here and in contrast to the majority of these suggestions is that it demonstrates the advantage of production of antimicrobial compounds in bottlenecks during the stationary growth phase. National Center for Biotechnology Information , U. Journal List Proc Biol Sci v. Published online Sep 5. Received May 29; Accepted Aug This article has been cited by other articles in PMC.

Abstract Bacteriocins are bacterial proteinaceous toxins with bacteriostatic or bacteriocidal activity towards other bacteria.

Introduction When provided with ecological opportunity, new bacterial genotypes lead to adaptive variation and thereby polymorphic populations [ 1 , 2 ]. Overview on social models that illustrate distinct types of selection of bacteriocins, a the competitive model concerning colicins and b the intraguild predation model concerning LAB bacteriocins.

P, bacteriocin producer; S, bacteriocin susceptible; Selection of lactic acid bacterial bacteriocin production during population bottlenecks We discuss here first the nature of the different environments facing colicin and LAB bacteriocin producers and will bring forward the proposal that LAB populations in their natural environments are facing bottlenecks that offer bacteriocin producers a fitness advantage owing to a higher degree of survival.

Characteristics of the different growth phases for a bacteriocin producer in a batch culture. Selected features of lactic acid bacterial bacteriocins and their producers that support an intraguild predation model a Inhibition spectrum and occurrence of resistant target cells Because the LAB bacteriocin producers are likely to meet ever-changing lineages of target cells in successive bottleneck situations, the model requires that the LAB bacteriocins exhibit relative broad target spectra in order to improve fitness of the producing cells.

Conclusions Selfishness, as a social interaction, appears to be promoted by bacteriocin-producing LAB in batch culture habitats that allow for IGP. Acknowledgements We thank two anonymous referees for comments. Adaptive radiation in a heterogeneous environment. Nature , 69— Clonal adaptive radiation in a constant environment. Science , — Local dispersal promotes biodiversity in a real-life game of rock-paper-scissors. Nature , — Molecular mechanisms of bacteriocin evolution.

Structured habitats and the evolution of anticompetitor toxins in bacteria. USA 78 , — Spatial polymorphism of bacteriocins and other allelopathic traits. Chemical warfare from an ecological perspective. USA 99 , — The ecology and evolution of bacteriocins. The ecological role of bacteriocins in bacterial competition. Spite and the scale of competition. Social evolution theory for microorganisms. Altruism, spite, and greenbeards. Identification and characterization of Enterococcus species isolated from forage crops and their influence on silage fermentation.

S 99 doi: S 99 [ PubMed ] [ Cross Ref ]. Isolation and characterization of lactic acid bacteria from lakes. The ecology of the streptococci. Broad and complex antifungal activity among environmental isolates of lactic acid bacteria. Isolation and identification of lactic acid bacteria from soil using an enrichment procedure. Identification of plant-associated enterococci. Isolation and characterization of lactic acid bacteria from soils in vineyards. Production of class II bacteriocins by lactic acid bacteria; an example of biological warfare and communication.

Antonie Van Leeuwenhoek 81 , — The continuing story of class IIa bacteriocins. Nonlantibiotic antibacterial peptides from lactic acid bacteria. Selection and fitness in bacteriocin-producing bacteria. B , — Bacteriocins of Gram-positive bacteria. Regulation of bacteriocin production in Streptococcus mutans by the quorum-sensing system required for development of genetic competence.

Quorum sensing by peptide pheromones and two-component signal-transduction systems in Gram-positive bacteria. The SapB morphogen is a lantibiotic-like peptide derived from the product of the developmental gene ramS in Streptomyces coelicolor.

USA , 11 —11 Regulation of antimicrobial peptide production by autoinducer-mediated quorum sensing in lactic acid bacteria. Antonie Van Leeuwenhoek 82 , — Lantibiotics produced by lactic acid bacteria: Use of Lactobacillus plantarum LPCO10, a bacteriocin producer, as a starter culture in Spanish-style green olive fermentations.

The ecology and evolution of intraguild predation: A theoretical framework for intraguild predation. Intraguild prey suffer from enrichment of their resources: Ecology 82 , — CO;2 [ Cross Ref ]. Productivity, dispersal and the coexistence of intraguild predators and prey. Bacteriocin production by lactic acid bacteria isolated from Rioja red wines. Microbial analysis of Malaysian tempeh, and characterization of two bacteriocins produced by isolates of Enterococcus faecium.

Ribosomally synthesized antibacterial peptides in Gram positive bacteria. Targets 3 , — The role and application of enterococci in food and health. Periodic selection, infectious gene exchange and the genetic structure of E. Periodic selection in Escherichia coli. USA 37 , — Compensatory mutations, antibiotic resistance and the population genetics of adaptive evolution in bacteria. Genetics , — Temporal changes in the frequency of colicinogeny in Escherichia coli from house mice.

Microbiology , — Bacteriocin diversity and the frequency of multiple bacteriocin production in Escherichia coli.

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This usually results in the worker removing her abdomen and not depositing her eggs. Aggression and punishment are not just found in insects. For example, in naked mole rats , punishments by the queen are a way she motivates the lazier, less-related workers in their groups. Reeve found that if the queen is removed when colonies are satiated, there is a significant drop in weight of the active workers because the lazier workers are taking advantage of the system.

Punishment is also a method used by cichlid Neolamprologous pulcher in their cooperative breeding systems. It is a pay-to-stay system where helper fish are allowed to stay in certain territories in exchange for their help. Researchers theorize that this system developed because the fish are usually not closely related so kinship benefits have little impact , and because there is a high level of predation risk when the fish is outside the group therefore a strong motivator for the helper fish to stay in the group.

Rhesus monkeys also use aggression as a punishment. These animals have five distinct calls that they can "decide" to produce upon finding food. Whether they call or not are related to their gender and number of kins: However, sometimes when food is found, the individual "discoverer" do not call to attract the kins and presumably to share food. If lower ranked individuals find this discoverer to be in the food drop area of the experiment, they recruit coalition support against this individual by screaming.

The formed coalition then chases this individual away. If higher ranked individuals find this discoverer, they either chase the discoverer away or became physically aggressive towards the individual. Cheating and constraints of cheating are not limited to intraspecific interactions; it can also occur in a mutualistic relationship between two species.

A common example is the mutualistic relationship between cleaner fish Labroides dimidiatus and reef fish. Bshary and Grutter found that cleaner wrasse prefers the client tissue mucus over ectoparasites. Further studies revealed that in a lab setting, the cleaner fish undergoes behavioral change in face of deterrents against eating their preferential food.

In other trials, the plate of their preferential food source chased the cleaner fish when they eat it, mimicking "client chasing" in natural setting.

After only six learning trials, the cleaners learned to choose against their preference, indicating that punishment is potentially a very effective countermeasure against cheating in mutualistic relationships. Finally the countermeasures are not limited to organismal relationships. However, some bacteria are more mutualistic, while others are more parasitic because they consume the plant's resources but fixes little to no N2.

Moreover, these plants cannot tell whether the bacteria are more or less parasitic until they are settled in the plant nodules. To prevent cheating, these plants seem to be able to punish the rhizobium bacteria. In a series of experiments, researchers forced non-cooperation between the bacteria and the plants by placing various nodules in nitrogen-free atmosphere. Another well-known example of plant-organism interaction occurs between yuccas and yucca moths. The female yucca moths deposit their egg one at a time to the yucca flower.

At the same time, she also deposits a small amount of pollen from yucca flowers as nutrition for the yucca moths. Because most of the pollen is not consumed by the larva, yucca moths are therefore also the active pollinators for the yucca plant. Moreover, sometimes the female moths do not successfully deposit their eggs the first time, and may try again and again.

The yucca plant receives scars from the multiple attempts, but they also receive more pollen, since the moths are depositing pollen with every try. In this case, the yucca plant has little to no benefits from this interaction. However, the plant has a unique way of constraining this behavior. While the constraint against cheating often occurs directly to the individual, in this case, the constraint occurs to the individual's offspring.

The yucca plant can "abort" the moths by aborting the flowers. Pellmyr and Huth found that there is selective maturation for flowers that have low egg loads and high number of scars and therefore a high amount of pollen. From Wikipedia, the free encyclopedia. Proceedings of the Royal Society B: Dictyostelium as a model for social evolution". The variable outcome of cleaning symbioses". Proceedings of the Royal Society of London. Behavioral Ecology and Sociobiology.

In Priti Kumar Roy. Applied and Environmental Microbiology. Proceedings of the National Academy of Sciences. Journal of Evolutionary Biology. Retrieved from " https: Cheating Behavior Biological interactions. Views Read Edit View history. What essential virulence factor, that aids such spread, is produced by all three organisms?

The patient's vital signs include a dangerously low blood pressure. The patient's erythrocyte sedimentation rate ESR is above-normal. Which of the cytokines below most directly contributed to development of these symptoms? The solution in which antibiotics were dissolved had been sterilized by autoclaving. The IV infusion was stopped and the fluid cultured, but cultures on a variety of media were sterile.

Which of the following bacterial components would have been most effective in producing the patient's fever? D Outer membrane proteins. What process is promoted by these pili? A Adherence of bacteria to mammalian cells. B Inhibition of Complement activation. C Resistance to opsonization by antibodies. D Transfer of DNA between bacterial cells. E Transport of nutrients into bacterial cells. After sterilization, which bacterial component is it most important to remove?

A Lipids of the plasma inner membrane. E Proteases which activate complement. What part of LPS was responsible for its toxic effect? A Long repeating polysaccharide O-antigen. B Complex phosphorylated polysaccharide core. C Unsaturated fatty acids, released by hydrolysis.

D Disaccharide substituted with saturated fatty acids Lipid A. E Protein, freed from covalent linkage to polysaccharide by plasma proteases. Clinical isolates of this species typically have thick polysaccharide capsules; varieties without capsules seldom produce serious disease.

How do capsules increase the ability of S. A Inhibit binding of antibodies. B Directly toxic to phagocytic cells. C Inhibit activation of complement. D Inhibit phagocytosis by neutrophils. E Inhibit antigen presentation by MHC. F Not immunogenic, but mask immunogenic surface structure. Antibodies to which antigen are most important? D Type III secretion system.

He is treated with Penicillin G, but his parents discontinue the antibiotic after a few days because he feels much better and does not like to take pills.

Regulation of antimicrobial peptide production by autoinducer-mediated quorum sensing in lactic acid bacteria. Antonie Van Leeuwenhoek 82 , — Lantibiotics produced by lactic acid bacteria: Use of Lactobacillus plantarum LPCO10, a bacteriocin producer, as a starter culture in Spanish-style green olive fermentations.

The ecology and evolution of intraguild predation: A theoretical framework for intraguild predation. Intraguild prey suffer from enrichment of their resources: Ecology 82 , — CO;2 [ Cross Ref ]. Productivity, dispersal and the coexistence of intraguild predators and prey.

Bacteriocin production by lactic acid bacteria isolated from Rioja red wines. Microbial analysis of Malaysian tempeh, and characterization of two bacteriocins produced by isolates of Enterococcus faecium. Ribosomally synthesized antibacterial peptides in Gram positive bacteria. Targets 3 , — The role and application of enterococci in food and health.

Periodic selection, infectious gene exchange and the genetic structure of E. Periodic selection in Escherichia coli. USA 37 , — Compensatory mutations, antibiotic resistance and the population genetics of adaptive evolution in bacteria. Genetics , — Temporal changes in the frequency of colicinogeny in Escherichia coli from house mice.

Microbiology , — Bacteriocin diversity and the frequency of multiple bacteriocin production in Escherichia coli. Persistence of colicinogenic Escherichia coli in the mouse gastrointestinal tract. Antibiotic-mediated antagonism leads to a bacterial game of rock—paper—scissors in vivo. An application in cheddar cheese manufacture for a strain of Lactococcus lactis producing a novel broad-spectrum bacteriocin, lacticin Plantaricin W from Lactobacillus plantarum belongs to a new family of two-peptide lantibiotics.

Plasmid-associated bacteriocin production by a strain of Carnobacterium piscicola from meat. Bacteriocin production, plasmid content and plasmid location of enterocin P structural gene in enterococci isolated from food sources.

Detection, purification, and partial characterization of Plantaricin-C, a bacteriocin produced by a Lactobacillus plantarum strain of dairy origin. Anti- Listeria effect of enterocin A, produced by cheese-isolated Enterococcus faecium EFM01, relative to other bacteriocins from lactic acid bacteria.

Genomic subpopulations within the species Pediococcus acidilactici detected by multilocus typing analysis: Microbiology , — [ PubMed ]. Potential of lactic streptococci to produce bacteriocin. Applications of the bacteriocin, nisin. Antonie Van Leeuwenhoek 69 , — On r- and K- selection.

The concept of r- and K- selection: Studies on the life and death of bacteria in the senescent phase in aging cultures and the probable mechanisms involved. Enhancement of proteolysis by a Lactococcus lactis bacteriocin producer in a cheese model system. Requirement of autolytic activity for bacteriocin-induced lysis.

Permeabilization and lysis induced by bacteriocins and its effect on aldehyde formation by Lactococcus lactis. Antimicrobial activity of lacticin against clinical Clostridium difficile strains. A lactin producing adjunct culture increases starter lysis while inhibiting nonstarter lactic acid bacteria prolifertion during cheddar cheese ripening. Autolytic system of Staphylococcus simulans Antilisterial activity of peptide AS and study of changes induced in the cell envelope properties of an ASadapted strain of Listeria monocytogenes.

Mode of action of Lactococcin B, a thiol activated bacteriocin from Lactococcus lactis. Bacteriolytic activity caused by the presence of a novel lactococcal plasmid encoding Lactococcin-A, Lactococcin-B, and Lactococcin-M. Mode of action of Pediocin Ach from Pediococcus acidilactici H on sensitive bacterial strains.

Autolytic activity and pediocin-induced lysis in Pediococcus acidilactici and Pediococcus pentosaceus strains. Bactericidal mode of action of plantaricin C. Microbial solutions to microbial problems; lactococcal bacteriocins for the control of undesirable biota in food.

Growth of facultatively heterofermentative lactobacilli on starter cell suspensions. Fermentation of carbohydrates from cheese sources by non-starter lactic acid bacteria isolated from semi-hard Danish cheese.

DNA as a nutrient novel role for bacterial competence gene homologs. Effects of Lactococcus lactis on composition of intestinal microbiota: Effect of broad- and narrow-spectrum antimicrobials on Clostridium difficile and microbial diversity in a model of the distal colon.

Cannibalism by sporulating bacteria. Spite and the scale of competition in Pseudomonas aeruginosa. The social lives of microbes. Cooperation, virulence and siderophore production in bacterial parasites. B , 37— Cooperation and competition in pathogenic bacteria. Cloning of two bacteriocin genes from a lactococcal bacteriocin plasmid.

Cloning, sequencing, and expression in Escherichia coli of lcnB, a third bacteriocin determinant from the lactococcal bacteriocin plasmid p9B Chemical and genetic characterization of bacteriocins produced by Carnobacterium piscicola LV17B. Characteristics and genetic determinant of a hydrophobic peptide bacteriocin, carnobacteriocin A, produced by Carnobacterium piscicola LV17A.

Antagonistic activity of Lactobacillus plantarum C Comparative studies of class IIa bacteriocins of lactic acid bacteria. Biochemical and genetic evidence that Enterococcus faecium L50 produces enterocins L50A and L50B, the sec-dependent enterocin P, and a novel bacteriocin secreted without an N-terminal extension termed enterocin Q.

Enterocin B, a new bacteriocin from Enterococcus faecium T which can act synergistically with enterocin A. The tragedy of the commons.

Lactic acid bacteria, their metabolic products and interference with microbial growth. Strong antimicrobial activity of Lactobacillus rhamnosus GG against Salmonella typhimurium is due to accumulation of lactic acid. Variations in tolerance of Listeria monocytogenes to nisin, pediocin PA-1 and bavaricin A. Natural variation in susceptibility of Listeria strains to class IIa bacteriocins. Intra-specific variation of Lactobacillus plantarum and Lactobacillus pentosus in sensitivity towards various bacteriocins.

Antonie Van Leeuwenhoek 85 , — Interactions of nisin and pediocin PA-1 with closely related lactic acid bacteria that manifest over fold differences in bacteriocin sensitivity. Differences in susceptibility of Listeria monocytogenes strains to sakacin P, sakacin A, pediocin PA-1, and nisin. Modifications of membrane phospholipid composition in nisin-resistant Listeria monocytogenes Scott A.

High-level resistance to class IIa bacteriocins is associated with one general mechanism in Listeria monocytogenes. Frequency of bacteriocin resistance development and associated fitness costs in Listeria monocytogenes. Fitness costs associated with class IIa bacteriocin resistance in Listeria monocytogenes B Divercin V41, a new bacteriocin with two disulphide bonds produced by Carnobacterium divergens V Comparative studies of immunity proteins of pediocin-like bacteriocins.

The Black Queen Hypothesis: MBio 3 , e Genetic structure of the Enterococcus faecalis plasmid pad1 encoded cytolytic toxin system and its relationship to lantibiotic determinants.

Co-ordinated bacteriocin production and competence development:

Removal charlotte

In many sexually reproducing species such as this, some males can access mates by exploiting resources of more competitive males. In these instances, several factors contribute to the decision to switch between mating strategies. For example, in the European tree frog, a sexually competitive as in, perceived to be attractive by females male tend to call to attract mates. This is often referred to as the "bourgeois" tactic.

In this instance, the males can gain access to female without having to defend territories or acquiring additional resources which often serve as the basis for attractiveness. This is referred to as the "parasitic" tactic, where the smaller male effectively cheats its way to accessing females, by reaping the benefit of sexual reproduction without contributing resources that normally attract females.

Studies find that mating strategies are highly adaptable and depend on a variety of factors, such as competitiveness, energetic costs involved in defending territory or acquiring resources.

Like many other organisms, bacteria rely on iron intake for its biological processes. Some bacteria have evolved siderophores , iron-chelating particles that seek and bring back iron for the bacteria. Siderophores are not necessarily specific to its producer - sometimes another individual could take up the particles instead. Under low-iron conditions, P.

However, when iron is readily available, either from freely diffusing in environment or another bacterium's siderophores, P. One study showed that when P. This result suggested that P.

More studies, however, suggested that P. In another study, two strains of P. One strain, known as the producer, produced a higher level of siderophores, which meant that other strain, known as the non-producer, ceased siderophore production in favor of using the other's siderophores.

Although one would expect that the non-producer would outcompete the producer, like the P. Further experiments suggested that this cheating prevention may be due to interactions with other microbes in the soil influencing the relationship or the spatial structure of the soil preventing siderophore diffusion and therefore limiting the non-producer's ability to exploit the producer's siderophores.

By definition, individuals cheat to gain benefits that their non-cheating counterparts do not receive. How then can a cooperative system exist in face of these cheaters? One answer is that the cheaters actually have a reduced fitness compared to the non-cheaters. In a study by Dandekar et al. In this case, the resources are publicly shared proteases that break down a food source like casein, and privately used adenosine hydrolase, which breaks down another food source, adenosine.

The problem arises when some individuals "cheaters" do not respond to these quorum sensing signals and therefore do not contribute to the costly protease production yet enjoys the benefits of the broken down resources. In wild populations where the presence of adenosine is common, this is an explanation for how individuals that cooperate could have higher fitness than those that cheat, thereby suppressing the cheaters and maintaining cooperation.

Cheating is also commonly found in insects. The social and seemingly altruistic communities found in insects such as ants and bees provide ample opportunities for cheaters to take advantage of the system and accrue additional benefits at the expense of the community. Sometimes, a colony of insects is called a " superorganism " for its ability to take on properties greater than those of the sum of individuals.

A colony of insects in which different individuals are specialized for specific tasks means a greater colony production and greater efficiency. Therefore, though it is beneficial for one individual to have its own offspring, it is collectively beneficial to have the queen lay the eggs.

Therefore, a system of worker and queen policing exists against worker-laid eggs. One form of policing occurs by the oophagy of the worker-laid eggs, found in many ant and bee species. The other form of policing occurs through aggression towards egg-laying workers.

In a species of tree wasp Dolichovespula sylvestris , Wenseleers et al. The workers and the queen would grab the egg-laying worker and try to sting her or push her off the cell. This usually results in the worker removing her abdomen and not depositing her eggs.

Aggression and punishment are not just found in insects. For example, in naked mole rats , punishments by the queen are a way she motivates the lazier, less-related workers in their groups.

Reeve found that if the queen is removed when colonies are satiated, there is a significant drop in weight of the active workers because the lazier workers are taking advantage of the system. Punishment is also a method used by cichlid Neolamprologous pulcher in their cooperative breeding systems.

It is a pay-to-stay system where helper fish are allowed to stay in certain territories in exchange for their help. Researchers theorize that this system developed because the fish are usually not closely related so kinship benefits have little impact , and because there is a high level of predation risk when the fish is outside the group therefore a strong motivator for the helper fish to stay in the group. Rhesus monkeys also use aggression as a punishment. These animals have five distinct calls that they can "decide" to produce upon finding food.

Whether they call or not are related to their gender and number of kins: However, sometimes when food is found, the individual "discoverer" do not call to attract the kins and presumably to share food. If lower ranked individuals find this discoverer to be in the food drop area of the experiment, they recruit coalition support against this individual by screaming. The formed coalition then chases this individual away. If higher ranked individuals find this discoverer, they either chase the discoverer away or became physically aggressive towards the individual.

Cheating and constraints of cheating are not limited to intraspecific interactions; it can also occur in a mutualistic relationship between two species. A common example is the mutualistic relationship between cleaner fish Labroides dimidiatus and reef fish.

Bshary and Grutter found that cleaner wrasse prefers the client tissue mucus over ectoparasites. Further studies revealed that in a lab setting, the cleaner fish undergoes behavioral change in face of deterrents against eating their preferential food.

In other trials, the plate of their preferential food source chased the cleaner fish when they eat it, mimicking "client chasing" in natural setting. After only six learning trials, the cleaners learned to choose against their preference, indicating that punishment is potentially a very effective countermeasure against cheating in mutualistic relationships. Finally the countermeasures are not limited to organismal relationships.

However, some bacteria are more mutualistic, while others are more parasitic because they consume the plant's resources but fixes little to no N2. Moreover, these plants cannot tell whether the bacteria are more or less parasitic until they are settled in the plant nodules. To prevent cheating, these plants seem to be able to punish the rhizobium bacteria. In a series of experiments, researchers forced non-cooperation between the bacteria and the plants by placing various nodules in nitrogen-free atmosphere.

Another well-known example of plant-organism interaction occurs between yuccas and yucca moths. The female yucca moths deposit their egg one at a time to the yucca flower. At the same time, she also deposits a small amount of pollen from yucca flowers as nutrition for the yucca moths. Because most of the pollen is not consumed by the larva, yucca moths are therefore also the active pollinators for the yucca plant.

Moreover, sometimes the female moths do not successfully deposit their eggs the first time, and may try again and again. The yucca plant receives scars from the multiple attempts, but they also receive more pollen, since the moths are depositing pollen with every try.

In this case, the yucca plant has little to no benefits from this interaction. However, the plant has a unique way of constraining this behavior. While the constraint against cheating often occurs directly to the individual, in this case, the constraint occurs to the individual's offspring.

The yucca plant can "abort" the moths by aborting the flowers. Pellmyr and Huth found that there is selective maturation for flowers that have low egg loads and high number of scars and therefore a high amount of pollen. From Wikipedia, the free encyclopedia. Proceedings of the Royal Society B: What was the most likely source of this infection?

Home-grown tomatoes brought to the patient by his family. Direct contact with a health care worker. Inhalation of airborne spores. Fecal contamination of food or water. Which of the following is likely to have played largest role in this reaction? A humoral immune response to bacterial surface antigens. A cell-mediated immune response to bacteria. Secretion of cytokines by monocytes in response to stimulation by LPS [endotoxin]. Release of granule contents by mast cells and basophils.

Secretion of a bacterial superantigen toxin that activates TH cells. Which metal is acquired by the majority of these systems? Which of the following organisms is most likely?

However, the safranin counter-stain was accidentally omitted. If you looked at this preparation under the microscope, which line below best describes what you should expect to see? Which phrase below best describes infections like this one? Other species of bacteria also often present. Initiated by ingestion of spores. Can be successfully treated with aminoglycosides alone.

Contracted by the respiratory route. By what route are such infections most commonly acquired? Respiratory route, followed by spread from the anterior nares. Respiratory route, followed by spread from the oro-pharyngeal region.

Fecal-oral route, followed by colonization of the intestine and then the perineum. Intestinal infection, followed by spread of bacteria to the urethra via the bloodstream. Which of the following bacterial structures is primarily an organelle of adhesion?

A lumbar puncture is performed and a smearof cerebrospinal fluid is Gram-stained. Each high-power field contains many neutrophils, red cells, and Gram-positive cocci.

What does the blue color of the cocci indicate about the structure of their envelopes? A sputumsmear is stained using the same technique used on the demonstration slides in the lab. If the patient indeed has Tuberculosis, and the stain is done with proper procedure, how should the bacteria appear?

Cocci, which stain dark red. Cocci, which stain dark green. Cocci, which stain dark blue. Bacilli, which stain dark red. Bacilli, which stain dark green. Bacilli, which stain dark blue. There is no pasthistory of similar infections. Which of the following was most greatly responsible for the fever and hypotension?

Capsule polysaccharide, which activated Complement by the Alternate Pathway. Lipopolysaccharide, which bound to Toll-like receptors. Common pili, which allowed bacteria to bind tightly to endothelial cells. Porin proteins, which allowed bacterial toxins to exit the periplasm. Which inflammatory components are present inthe envelopes of Gram-positive bacteria?

Core and Lipid A of Lipopolysaccharide. O-antigen chains of Lipopolysaccharide. Porin proteins and periplasmic lipoproteins. Peptidoglycan and teichoic acids. How would you expect this unusual structural feature to affect their biology? Their Lipid A should produce intense inflammation. They should be highly-resistant to osmotic lysis.

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Both colony types contained Gram-positive cocci. The organism is more virulent than other staphylococci. The organism is likely to produce a superantigen toxin. The patient is in little or no danger of developing septic shock. The Gram-positive staining was likely the result of improper laboratory procedure. The catheter entry site is likely to have been infected by normal skin flora. How does Protein A aid in virulence? Binds the Fc region of IgG, decreases opsonization.

Binds Factor H, prevents activation of complement. Extracts iron from plasma proteins. Promotes tight binding of bacteria to extracellular matrix. An HIV-positive patient with hemoptysis. A sample of sputum is obtained and a smear is acid-fast-stained using the red dye carbol-fuchsin. Irregularly-staining red branching filaments. Red acid-fast cocci, in grape-like clusters. Three days later, there is induration and erythema, 32 mm in diameter, at the site of injection, a positive test result.

What process produced the induration and erythema? Induction of a primary antibody response. Invasion and lysis of epithelial cells by bacteria. Release of inflammatory cell-envelope components from bacteria. The probable diagnosis was readily established by x-ray, direct smear, and skin testing. Why was the labor- and time-intensive culture procedure performed?

Only highly-virulent mycobacteria grow on the media used for culture. Rapid growth of mycobacteria correlates with high virulence. Choose the single best answer to each question.

What essential virulence factor, that aids meningeal spread, is produced by all four organisms? Epidemiologists found that, three days before the outbreak, the class had gone to a local restaurant for a party.

All children who became ill, and none who did not, had eaten hamburgers. Later it was found that some lactose fermenters failed to ferment sorbitol. Which organism is most strongly suggested by the laboratory and epidemiologic data? Gram-stained smear of exudate contains neutrophils and Gram-negative diplococci, many of them intracellular.

On his second visit, Gram-stained smear of exudate contains neutrophils but no bacteria are visible, and culture of exudate produces no colonies on Sheep blood, Chocolate, or Thayer-Martin agars in elevated CO2. Which two species below are most likely to have caused his infections?

Klebsiella pneumoniae and Chlamydia pneumoniae. Neisseria meningitidis and Chlamydia trachomatis. Legionella pneumophila and Mycoplasma pneumoniae.

Treponema pallidum and Ehrlichia phagocytophila. Neisseria gonorrhoeae and Mycoplasma hominis. A young woman with a post-chemotherapy infection. A year-old woman with leukemia was treated with a brief intensive course of cytotoxic drugs. Ten days after therapy began she developed fever and shortness of breath. A CBC complete blood count showed her to be highly neutropenic.

Chest x-ray revealed a dense lesion in her left lung. Under the microscope the fuzzy colonies contained hyphae with septa which branched at acute angles, and conidia in chains. In a silver-stained biopsy of the lung lesion branching hyphae were seen in tissue. Cytokine production by leukemic cells. Killing of dividing cells by cytotoxic anti-cancer drugs. Killing by toxins secreted by the pathogen. Induction of apoptosis by the pathogen.

A genetic defect in neutrophil production. During the procedure a biopsy of the stomach epithelium is obtained. Which observation would suggest Helicobacter pylori as the cause of illness?

Curved or spiral bacteria seen in the biopsy after silver staining. Biopsy shows infiltration of gastric epithelium by lymphocytes. Ingested isotope-labeled nitrate is converted to nitrite in the stomach.

Bacteria are found in stomach fluid, but not in contact with the gastric epithelium. On examination his neck is mildly stiff. Gram stain of the patient's CSF reveals neutrophils and numerous Gram-negative cocci, many in pairs. Which organism below is most likely? During surgery foul-smelling purulent material is aspirated from the infected area.

Gram stain of this material contains a mixture of Gram positive cocci, Gram-positive rods, and many Gram-negative rods. Aerobic culture on sheep blood agar yields many colonies of enterococci and a few colonies of E. Which organism is most likely to represent the majority of the Gram-negative rods seen when peritoneal exudate was stained? A woman with neurological illness. A few hours later she develops difficulty speaking, bilateral weakness of her arms, nausea, vomiting, dizziness, blurred vision, and dry mouth.

However she is alert, oriented, and has no fever. If this is botulism, by what mechanism did Clostridium botulinum produce her signs and symptoms? Bound to Toll-like receptors and stimulated production of inflammatory cytokines.

Injected proteins into neurons via a type III secretion system. Secreted a protein toxin that enters mammalian neurons and blocks synaptic transmission. Released peptidoglycan and other inflammatory components of the cell envelope.

Bacteremic spread followed by infection of multiple tissues: What property of C. Produces airborne spores not easily killed by boiling. Vegetative cells grow best at cooking temperatures. Extremely resistant to gastric acid.

Thick peptidoglycan renders cells resistant to heat, cold, and drying. Surface proteins inhibit digestive hydrolases. A year-old man has high fever and elevated white count. Blood cultures are obtained. He is treated with a broad spectrum cephalosporin plus an aminoglycoside. The next day the laboratory reports that cultures contain catalase positive Gram-positive cocci in clusters.

Identification of the organism and determination of antibiotic sensitivity are underway. Pending arrival of these results, the cephalosporin is replaced with vancomycin. Cephalosporins as a class have a narrower spectrum of action than vancomycin.

The lab results suggest staphylococci, many of which are resistant to cephalosporins. Lysis of bacteria by cephalosporins may result in a massive inflammatory reaction.

Vancomycin is a bactericidal antibiotic whereas cephalosporins are only bacteriostatic. The organism is identified as Staphylococcus aureus. Antibiotic sensitivity testing results are as follows: Small non-conjugative plasmid that encodes a penicillinase.

There is no D-ala-D-ala in the side chains of peptidoglycan. No peptidoglycan is present in the cell wall. Methylation of ribosomal RNA. Cross-linking of peptidoglycan chains by transpeptidases.

Enzymatic activity of dihydrofolate reductase. Peptide bond formation by bacterial ribosomes. It is 10 cm in diameter and ulcerated. Surrounding tissue is red and markedly swollen. The ulcer is healing to produce a black scab. A swab of the ulcer contains large Gram-positive rods. Soon afterwards, he becomes ill. He reports a 5-day history of fever, malaise, and headache.

Lesions are cm in diameter, oval with somewhat irregular outlines, with cm red borders and cm central red areas, separated by a belt of paler skin. Which diagnosis is most likely?

The patient has a cat and reports that a few days ago the wretched ungrateful creature bit her on the right hand. What pathogen is most strongly suggested by the history? A young woman with an abscess. A year-old female college student went to the Student Health Service because of fever, myalgia, and a five-cm abscess: This was lanced, drained, and disinfected.

She was given antibiotics and acetaminophen Tylenol. Late that day her roommate found her disoriented and took her to the Emergency Room. Her blood pressure was below normal and her pulse elevated. She showed no signs of meningitis but was lethargic and reported severe muscle aches. The next morning she was still hypotensive and showed signs of liver jaundice and kidney poor urine output dysfunction. Blood levels of liver and muscle enzymes were elevated. The preliminary diagnosis was Toxic Shock Syndrome.

Bacteria infected these sites by gaining access to the bloodstream from the abscess. A bacterial exotoxin acted on the central nervous system; organ damage was a secondary result. Lipopolysaccharide released from dying bacteria caused monocytes to produce inflammatory cytokines.

A bacterial exotoxin stimulated production of toxic levels of inflammatory cytokines by T cells. Bacteria bound to plasma membrane receptors of nerve, muscle, and kidney, and induced apoptosis. Dilation of small blood vessels.

Increase in permeability of small blood vessels. Increased responsiveness of local sensory nerve endings. Infiltration of tissue by inflammatory cells. Two hours later he arrives at the Emergency Room with a red, swollen wrist and a fever of 40oC. What process would you expect to have been most effective in producing his fever? Binding of O-antigen by IgG antibodies. Binding of Toll-like Receptors by Lipid A. Binding of magnesium ions by core polysaccharide. Binding of porin proteins by siderophores.

MRI imaging demonstrated inflammation of the T8-T9 vertebral bodies consistent with osteomyelitis. A bone marrow biopsy, when cultured, produced colonies of Gram-positive cocci. Colonies on Sheep blood agar were mm in diameter, off-white and beta-hemolytic. Colonies on Brain-heart infusion BHI agar were mm in diameter and golden yellow.

Catalase and coagulase tests were positive. What is the most likely pathogen? The filaments were also weakly acid-fast. The organisms grew in aerobic culture.

Isolates from all cases are of serotype O A Gram-stained smear of exudate contains abundant neutrophils and slender Gram-negative rods. A sample is sent for culture and he is treated with a broad-spectrum antibiotic. The Gram-negative rod grows on Chocolate agar but not on standard Sheep blood agar when plates are cultured in room air. Which of the following organisms is most likely? Isolates which produce less-serious disease usually lack capsules.

Infection with non-encapsulated isolates results in protective immunity to them. In such an environment, success is expected to depend on fast proliferation, and broad-range bacteriocin production will be of less importance. On the contrary, it is characteristic that LAB bacteriocin producers can be found in a range of habitats. Although food products predominate among sources of LAB bacteriocin producers [ 41 — 43 , 45 , 54 — 63 ], the external environment or animals must be considered the primary habitat for LAB, whereas food products, in most cases, must be understood as secondary habitats.

Here, we will address only the external environment as a LAB habitat, as it provides a striking counterexample compared with the primary habitat facing colicin producers.

The extensive fermentative abilities of LAB indicate that often the natural environment for these bacteria is decaying organic material, which can be viewed as providing the social arena for a batch culture. Thus, the natural habitat of a LAB is characterized by the two very different conditions of feast and famine characteristic for batch cultures summarized in table 1.

The selective forces under these two conditions have similarities to the theory of r and K selection, which describes two types of selection, one targeting traits in relation to carrying capacity K and the other traits in relation to the maximal intrinsic rate of natural increase r max [ 64 , 65 ].

The bottleneck phase can have a prolonged extension because the period of death is not necessarily a steady decrease but may be interrupted by multiple spurts in multiplication [ 66 ]. Such spurts might reflect periodic selection events and thereby the addition of extra bottlenecks besides the general one provided by the nutrient limitation.

Overall, a strain may survive and dominate the population during a bottleneck in batch fermentations if it has a diminished death rate, similar to what has been argued to be the case for bacterial populations during a transmission phase [ 49 ].

This situation is opposed to the conditions during growth, where a strain may survive and dominate the population if it has an increased growth rate. Production of broad-spectrum bacteriocins allows, in mixed bacterial communities, at least a partial escape from this scenario. Although many LAB bacteriocins have a bacteriostatic mode of action, they may, however, contribute to an indirect bactericidal effect caused by an induction of autolysis of the sensitive target cell table 2 , a phenomenon that has been used for the acceleration of cheese ripening [ 80 ].

Those nutrients will, for a large part, consist of carbohydrates associated with the cell wall and DNA of the target cell, known to be important for bacterial including LAB survival [ 81 , 82 ] during the stationary growth phase [ 83 ].

Indeed, this role for bacteriocin-producing LAB has been suggested previously as one of the possible functions for Streptococcus mutans bacteriocins [ 31 ]. It is tempting to speculate that the continuous culture systems that constitute the evolutionary context for colicins do not play a similar role for LAB bacteriocins.

Studies examining the effect of selected bacteriocins on the composition of intestinal microbiota, however, gives contradictory results, and this aspect requires further research to reach a conclusion [ 84 , 85 ]. For bacteriocin-producing cells that survive by lysing and eating neighbouring cells, the outcome resembles the cannibalism described for sporulating Bacillus subtilis cells or the fratricide mechanism known from Streptococcus pneumonia [ 86 , 87 ].

However, the broad-spectrum activity observed for many LAB bacteriocins fits better into the social model of IGP, which also offers an alternative to direct competition envisaged for colicins outlined schematically in figure 1. An important parameter regarding selection for bacteriocin production is the dispersion from one habitat to another, i. By dispersion rate, we here mean the probability for separation of bacteriocin producers and sensitive as well as resistant or tolerant target cells during the transition phase s ; so they end up in new distinct habitats during the next round of batch fermentations.

If the dispersion rate is low, it will establish competition on a local scale and thereby promote, for example, spiteful behaviour, as for colicin producers [ 11 , 88 ]. Taking into consideration that the bottleneck habitats of LAB in the environment consist of settings, such as decaying vegetables, with a relatively long duration and a continuous dispersion taking place, it is not unreasonable to assume that the rate of dispersion in such a case instead is high, leading to competition on a global scale.

As for siderophores, it can be anticipated that the proportion of bacteriocin producers in the population will be positively affected if competition acts on a global scale, i. A critical difference to the siderophore system is that the resource the sensitive target cells might mutate into competitors resistant target cells.

The fraction of resources that vanish in this way can also be assumed to depend on the scale of competition being less the more global the social arena is. The importance of scale might however be diminished if more than one type of bacteriocin is produced. The first multiple bacteriocin-producing LAB described was a strain of Lactococcus lactis that produced several lactococcins [ 92 , 93 ], with a very narrow inhibition spectrum [ 62 ].

Shortly afterwards, multiple bacteriocin production was also discovered in Carnobacterium maltaromaticum [ 56 , 94 , 95 ]. The inhibition spectrum of the carnobacteriocins B1, BM1 and B2 is wider than that of the lactococcins A, B and M see the electronic supplementary material, table S1 and might reflect the type of niche carnobacteria reside in [ 19 ].

Other LAB that produce multiple bacteriocins have subsequently also been found in lactobacilli e. Lactobacillus plantarum [ 96 ] and Lactobacillus sakei [ 97 ] , leuconostocs e. Leuconostoc mesenteroides [ 98 ] and enterococci e. Enterococcus faecium , [ 43 , 99 — ]. The potential synergy effect by producing multiple bacteriocins probably diminishes the possibility for selection of resistant variants.

Such bacteria that could be considered as cheaters include a variety of Gram-positive lineages as well as Gram-negative bacteria, in general. However, Gram-positive tolerant lineages might be selected against if the scale of competition is global as described earlier, whereas Gram-negative bacteria are selected against owing to their increased sensitivity towards organic acids produced by LAB [ , ].

Because the LAB bacteriocin producers are likely to meet ever-changing lineages of target cells in successive bottleneck situations, the model requires that the LAB bacteriocins exhibit relative broad target spectra in order to improve fitness of the producing cells.

Indeed, several LAB bacteriocins exhibit such broad spectra towards target species that may be only remotely phylogenetically related, i. Thus, a survey of the literature showed that among selected class I bacteriocins, all 10 showed inhibition against genera other than that to which the producer organism belonged, and this was also the case for 25 out of 30 class II bacteriocins see the electronic supplementary material, table S1.

There is, however, frequently intraspecific variation in bacteriocin susceptibility among target cells [ 97 , — ], which result in the likelihood of the presence of tolerant lineages in mixed culture batch fermentations. The mechanism that confers resistance or tolerance to target cells is, in some instances, owing to differences in the membrane composition [ , , ], but other mechanisms e. There are indications that resistance phenotypes are associated with fitness costs [ , ].

As mentioned previously, bacteriocin-producing LAB contains an immunity gene s that confers resistance towards own bacteriocin s. In a few cases putative orphan , immunity genes without any clear bacteriocin partner have been reported [ 94 , , ].

The mechanisms for maintaining the presence of such genes in LAB populations will require additional studies, but their occurrence might be explained by the Black Queen hypothesis BQH proposed by Morris et al. We propose that the lack of fitness cost of bacteriocin production is not of overall importance in an IGP model but this devaluates the usefulness of the rock—paper—scissor model for LAB bacteriocins.

Another way to reduce the fitness cost of bacteriocin production is to assess whether the bacteriocin has moonlighting properties [ ], meaning that it serves cellular functions other than interbacterial warfare. An example is LAB bacteriocins that can also act as signal molecules in a quorum-sensing context [ 23 , 32 , 34 , 35 ]. Also, some bacteriocin-related molecules may exert biological roles unrelated to antagonism [ 31 , 33 , , ].

On the other hand, evidence exists that points towards additional cost of LAB bacteriocin production as LAB loci frequently contain numerous genes involved in bacteriocin production, immunity and secretion [ 19 , 23 — 27 , 34 , 35 , 44 , , ]. However, it should be noted that in the context of bottlenecks in batch fermentations, it is more relevant to study the presence of fitness costs associated with survival. Selfishness, as a social interaction, appears to be promoted by bacteriocin-producing LAB in batch culture habitats that allow for IGP.

Contrarily, the production of colicins has been extensively used as a convenient microbial model for the social interaction spite [ 89 , ].

The LAB bacteriocin systems described here may also be perceived, to some degree, as an example of altruism rather than of selfishness when tolerant or resistant lineages in addition to sensitive target cells are present in the environment of the producer. This combination of potentially two types of social interactions makes LAB bacteriocins an interesting model to explore.

This concerns the fact that in many complex microbial communities, the majority of species loose genes necessary for providing leaky common goods when this instead can be provided by a few key species, the black queens. As bacteriocin producers consume metabolites provided by sensitive strains, at least in theory, the producers may lose genes necessary for metabolizing specific substrates e. In this analogy, IGPrey may, to some extent, resemble black queens with the difference that there most likely are more than just a few such lineages present in a typical LAB batch environment.

It would be of interest to examine whether bacteriocin producers may in fact carry fewer genes for metabolizing, for instance, specific carbohydrates than is the case for IGPrey lineages. Staying in the cards game analogy, one could compare LAB bacteriocin production to the game of Casino.

One aim is here to capture as many cards as possible equivalent to nutrients from a layout. However, one can only obtain cards bacteriocin sensitive cells that match the cards of the players' hand bacteriocin producers. Selfishness has, compared with altruism and spite, received little recent attention in microbial models. However, this type of social behaviour is suitable for exploring general ecological interactions such as IGP, which is a very common phenomenon in nature [ 37 , ].

Microbial examples have primarily focused on ciliates acting as predator and intraguild prey, whereas bacteria provided the common resource [ 39 , ].

There are few reports, if any, on IGP including only bacteria, but it has to be kept in mind that the example offered here does not include a genuine IGP mechanism as the general resource for the IGPredator and IGPrey is nutrients from decaying organic material and thus not a prey organism as such.

Still, the LAB bacteriocin mechanism offers a model that might be useful for examination of more general aspects of IGP, such as the relationship between IGP and resource competition.

It has been shown theoretically [ ] and experimentally, using ciliates and bacteria [ 39 ], that nutrient-rich environments allows predominance of the IGPredator. This is similar to the population dynamics predicted and observed for colicin producers [ 5 , 7 , 10 , ]. Indeed, the induction of bacteriocins in the late exponential or stationary growth phase by quorum sensing appears to present just such a polymorphism.

An example could be the Streptomyces genus, which produces the majority of the natural antibiotics known to man. The genus is primarily found in the soil where it gets nutrition from decaying vegetation [ ]. The habitat is thus expected to create a bottleneck situation as has been discussed for LAB in this review.

Interestingly, like LAB bacteriocin production, antibiotic production in Streptomyces is not initiated before entering the stationary phase, where growth rate slows down and production of aerial mycelium begins [ ].

Both protection against other microbes and recycling of killed sensitive cells have been proposed [ ] as an explanation for this timing of antibiotic production. The induction of antibiotic production upon nutrient exhaustion bottleneck coinciding with the production of aerial mycelium dispersion fits very well into the IGP model presented here and it would be of interest to examine experimentally whether this model could be used to explain Streptomyces antibiotic production.

We have until now only discussed fitness of LAB bacteriocin producers during population bottlenecks in environments where they have experienced a previous logarithmic phase of growth. We have described the dispersion to new potential habitats only as a parameter to adjust the scale of competition with a high degree of dispersion leading to a global scale of competition.

Even so, it can be anticipated that IGP is an important component of the social behaviour of bacteriocin-producing LAB. Future studies should test the validity of this mechanism on both a mathematical and an empirical level. Such studies would quantify the magnitude of selection for bacteriocin producers under different bottleneck scenarios using microcosm evolution experiments. This would also illuminate the effects of habitats on the selection of types of social interactions.

In this regard, it should be considered that bottleneck scenarios may promote other survival strategies in addition to bacteriocin production, with the phenomenon of persister cells as an example [ ]. The strength of the IGP model proposed here and in contrast to the majority of these suggestions is that it demonstrates the advantage of production of antimicrobial compounds in bottlenecks during the stationary growth phase. National Center for Biotechnology Information , U.

Journal List Proc Biol Sci v. Published online Sep 5. Received May 29; Accepted Aug This article has been cited by other articles in PMC. Abstract Bacteriocins are bacterial proteinaceous toxins with bacteriostatic or bacteriocidal activity towards other bacteria.

Introduction When provided with ecological opportunity, new bacterial genotypes lead to adaptive variation and thereby polymorphic populations [ 1 , 2 ]. Overview on social models that illustrate distinct types of selection of bacteriocins, a the competitive model concerning colicins and b the intraguild predation model concerning LAB bacteriocins.

P, bacteriocin producer; S, bacteriocin susceptible; Selection of lactic acid bacterial bacteriocin production during population bottlenecks We discuss here first the nature of the different environments facing colicin and LAB bacteriocin producers and will bring forward the proposal that LAB populations in their natural environments are facing bottlenecks that offer bacteriocin producers a fitness advantage owing to a higher degree of survival.

Characteristics of the different growth phases for a bacteriocin producer in a batch culture. Selected features of lactic acid bacterial bacteriocins and their producers that support an intraguild predation model a Inhibition spectrum and occurrence of resistant target cells Because the LAB bacteriocin producers are likely to meet ever-changing lineages of target cells in successive bottleneck situations, the model requires that the LAB bacteriocins exhibit relative broad target spectra in order to improve fitness of the producing cells.

Conclusions Selfishness, as a social interaction, appears to be promoted by bacteriocin-producing LAB in batch culture habitats that allow for IGP. Acknowledgements We thank two anonymous referees for comments. Adaptive radiation in a heterogeneous environment. Nature , 69— Clonal adaptive radiation in a constant environment. Science , — Local dispersal promotes biodiversity in a real-life game of rock-paper-scissors.

Nature , — Molecular mechanisms of bacteriocin evolution. Structured habitats and the evolution of anticompetitor toxins in bacteria. USA 78 , — Spatial polymorphism of bacteriocins and other allelopathic traits. Chemical warfare from an ecological perspective. USA 99 , — The ecology and evolution of bacteriocins.

The ecological role of bacteriocins in bacterial competition. Spite and the scale of competition. Social evolution theory for microorganisms. Altruism, spite, and greenbeards. Identification and characterization of Enterococcus species isolated from forage crops and their influence on silage fermentation. S 99 doi: S 99 [ PubMed ] [ Cross Ref ]. Isolation and characterization of lactic acid bacteria from lakes. The ecology of the streptococci. Broad and complex antifungal activity among environmental isolates of lactic acid bacteria.

Isolation and identification of lactic acid bacteria from soil using an enrichment procedure. Identification of plant-associated enterococci. Isolation and characterization of lactic acid bacteria from soils in vineyards. Production of class II bacteriocins by lactic acid bacteria; an example of biological warfare and communication. Antonie Van Leeuwenhoek 81 , — The continuing story of class IIa bacteriocins.

Nonlantibiotic antibacterial peptides from lactic acid bacteria. Selection and fitness in bacteriocin-producing bacteria. B , — Bacteriocins of Gram-positive bacteria. Regulation of bacteriocin production in Streptococcus mutans by the quorum-sensing system required for development of genetic competence. Quorum sensing by peptide pheromones and two-component signal-transduction systems in Gram-positive bacteria.

The SapB morphogen is a lantibiotic-like peptide derived from the product of the developmental gene ramS in Streptomyces coelicolor.

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