Antagonistic interactions peak at intermediate genetic distance in clinical and laboratory strains of Pseudomonas aeruginosa

Schoustra, Sijmen E.; Dench, Jonathan; Dali, Rola; Aaron, Shawn D.; Kassen, Rees

doi:10.1186/1471-2180-12-40

Cited by 24 publications

(40 citation statements)

References 43 publications

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“…Although ammonia, NH 3 , is a waste product of L-serine catabolism (Hofmeister and Buckler 1993), the concentrations produced, even if all L-serine was consumed, would be buffered as lower-toxicity ammonium ion NH 1 4 (only 1#10 3 mol/L would remain as ammonia given the pH and temperature conditions; Emerson et al 1975). Although Pseudomonas aeruginosa produces a wide variety of anticompetitor compounds, they are unlikely to be effective, as invader and resident share a common genetic background (Bucci et al 2011;Inglis et al 2011;Schoustra et al 2012). Likewise, cross-feeding is another important interaction between microbes that has been observed to evolve in vitro (Rozen and Lenski 2000).…”

Section: Discussionmentioning

confidence: 99%

Here’s to the Losers: Evolvable Residents Accelerate the Evolution of High-Fitness Invaders

Gifford¹,

Toll-Riera²,

Kojadinovic³

et al. 2015

The American Naturalist

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Recent work has shown that evolvability plays a key role in determining the long-term population dynamics of asexual clones. However, simple considerations suggest that the evolvability of a focal lineage of bacteria should also be influenced by the evolvability of its competitors. First, evolvable competitors should accelerate evolution by impeding the fixation of the focal lineage through a clonal interference-like mechanism. Second, evolvable competitors should increase the strength of selection by rapidly degrading the environment, increasing selection for adaptive mutations. Here we tested these ideas by allowing a high-fitness clone of the bacterium Pseudomonas aeruginosa to invade populations of two low-fitness resident clones that differ in their evolvability. Both competition from mutations in the resident lineage and environmental degradation lead to faster adaptation in the invader through fixing single mutations with a greater fitness advantage. The results suggest that competition from mutations in both the successful invader and the unsuccessful resident shapes the adaptive trajectory of the invader through both direct competition and indirect environmental effects. Therefore, to predict evolutionary outcomes, it will be necessary to consider the evolvability of all members of the community and the effects of adaptation on the quality of the environment. This is particularly relevant to mixed microbial communities where lineages differ in their adaptive potential, a common feature of chronic infections. abstract: Recent work has shown that evolvability plays a key role in determining the long-term population dynamics of asexual clones. However, simple considerations suggest that the evolvability of a focal lineage of bacteria should also be influenced by the evolvability of its competitors. First, evolvable competitors should accelerate evolution by impeding the fixation of the focal lineage through a clonal interference-like mechanism. Second, evolvable competitors should increase the strength of selection by rapidly degrading the environment, increasing selection for adaptive mutations. Here we tested these ideas by allowing a high-fitness clone of the bacterium Pseudomonas aeruginosa to invade populations of two low-fitness resident clones that differ in their evolvability. Both competition from mutations in the resident lineage and environmental degradation lead to faster adaptation in the invader through fixing single mutations with a greater fitness advantage. The results suggest that competition from mutations in both the successful invader and the unsuccessful resident shapes the adaptive trajectory of the invader through both direct competition and indirect environmental effects. Therefore, to predict evolutionary outcomes, it will be necessary to consider the evolvability of all members of the community and the effects of adaptation on the quality of the environment. This is particularly relevant to mixed microbial communities where lineages differ in their adaptive potential, a...

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Section: Discussionmentioning

confidence: 99%

Here’s to the Losers: Evolvable Residents Accelerate the Evolution of High-Fitness Invaders

Gifford¹,

Toll-Riera²,

Kojadinovic³

et al. 2015

The American Naturalist

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“…It has been suggested that the mechanism underlying the variation in the antagonism effects of toxins like bacteriocins is caused by intraspecific resource competition. Recently Schoustra et al (2012), showed that antagonism among Pseudomonas aeruginosa strains increased at certain genetic distance. They suggested that targetting a particular group would have a direct effect on the competitors' resource use, and that, therefore, resource use and genetic distance were linked.…”

Section: Antagonism Influence In Community Assemblagementioning

confidence: 99%

Antagonism influences assembly of a Bacillus guild in a local community and is depicted as a food-chain network

Pérez-Gutiérrez¹,

López-Ramírez²,

Islas³

et al. 2012

The ISME Journal

124

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Understanding the principles that govern community assemblages is a central goal of ecology. There is limited experimental evidence in natural settings showing that microbial assembly in communities are influenced by antagonistic interactions. We, therefore, analyzed antagonism among bacterial isolates from a taxonomically related bacterial guild obtained from five sites in sediments from a fresh water system. We hypothesized that if antagonistic interactions acted as a shaping force of the community assembly, then the frequency of resistance to antagonism among bacterial isolates originating from a given site would be higher than the resistance to conspecifics originating from a different assemblage. Antagonism assays were conducted between 78 thermoresistant isolates, of which 72 were Bacillus spp. Sensitive, resistant and antagonistic isolates co-occurred at each site, but the within-site frequency of resistance observed was higher than that observed when assessed across-sites. We found that antagonism results from bacteriocinlike substances aimed at the exclusion of conspecifics. More than 6000 interactions were scored and described by a directed network with hierarchical structure that exhibited properties that resembled a food chain, where the different Bacillus taxonomic groups occupied specific positions. For some tested interacting pairs, the unidirectional interaction could be explained by competition that inhibited growth or completely excluded one of the pair members. This is the first report on the prevalence and specificity of Bacillus interactions in a natural setting and provides evidence for the influence of bacterial antagonist interactions in the assemblage of a taxonomically related guild in local communities.

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“…However, very closely related isolates, despite requiring similar resources, are often unable to inhibit each other due to shared resistance mechanisms (Hawlena et al, 2010a,b). Conflating predictions concerning ecological and genetic similarity suggests that inhibitory interactions should occur more frequently between genetically 'intermediate' competitors (Schoustra et al, 2012). Although inhibitory interactions do appear to occur more frequently between genetically 'intermediate' competitors in marine and host-associated bacterial populations, direct evidence that competition over resources promotes inhibitory interactions remains scant (Cordero et al, 2012;Hawlena et al 2012;Kinkel et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Bacteriocins and the assembly of natural Pseudomonas fluorescens populations

Bruce

West

Griffin

2016

J of Evolutionary Biology

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When competing for space and resources, bacteria produce toxins known as bacteriocins to gain an advantage over competitors. Recent studies in the laboratory have confirmed theoretical predictions that bacteriocin production can determine coexistence, by eradicating sensitive competitors or driving the emergence of resistant genotypes. However, there is currently limited evidence that bacteriocin-mediated competition influences the coexistence and distribution of genotypes in natural environments, and what factors drive interactions towards inhibition remain unclear. Using natural soil populations of Pseudomonas fluorescens, we assessed the ability of the isolates to inhibit one another with respect to spatial proximity in the field, genetic similarity and niche overlap. The majority of isolates were found to produce bacteriocins; however, widespread resistance between coexisting isolates meant relatively few interactions resulted in inhibition. When inhibition did occur, it occurred more frequently between ecologically similar isolates. However, in contrast with results from other natural populations, we found no relationship between the frequency of inhibition and the genetic similarity of competitors. Our results suggest that bacteriocin production plays an important role in mediating competition over resources in natural settings and, by selecting for isolates resistant to local bacteriocin production, can influence the assembly of natural populations of P. fluorescens.

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Antagonistic interactions peak at intermediate genetic distance in clinical and laboratory strains of Pseudomonas aeruginosa

Cited by 24 publications

References 43 publications

Here’s to the Losers: Evolvable Residents Accelerate the Evolution of High-Fitness Invaders

Here’s to the Losers: Evolvable Residents Accelerate the Evolution of High-Fitness Invaders

Antagonism influences assembly of a Bacillus guild in a local community and is depicted as a food-chain network

Bacteriocins and the assembly of natural Pseudomonas fluorescens populations

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