Trade-off Mechanisms Shaping the Diversity of Bacteria

Ferenci, Thomas

doi:10.1016/j.tim.2015.11.009

Cited by 161 publications

(139 citation statements)

References 85 publications

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“…Trade-offs are important means through which bacteria adapt to the environment and eventually promote increased bacterial diversity [53]. Allocation of resources to cell reproduction comes at the cost of neglecting the expression of proteins important for bacterial protection against environmental stresses, and vice-versa.…”

Section: Resultsmentioning

confidence: 99%

“…However, rpoS normally have a negative effect on fitness, as shown for strain MC4100 and to a lesser extent for LRT9. On the other hand, the presence of rpoS in strain E2348/69 was not disadvantageous, meaning that by keeping rpoS the bacterium did not have to trade stress resistance for nutritional competence, as stipulated by the SPANC balance [53]. …”

Section: Discussionmentioning

confidence: 99%

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RpoS role in virulence and fitness in enteropathogenic Escherichia coli

2017

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Enteropathogenic Escherichia coli (EPEC) is a diarrheagenic pathogen that afflicts infants in developing countries. The most important virulence trait of EPEC is its ability to intimately adhere to cells in the small intestine, and to elicit diarrhea. The alternative sigma factor RpoS is involved in the virulence of several bacterial species. RpoS coordinates the general stress response and accumulates in cells under stress or in the stationary phase. RpoS levels differ across E. coli strains. High-RpoS strains are highly resistant to environmental stresses, but usually display low nutritional competence, while low-RpoS strains show the opposite phenotype. Here we investigated whether RpoS plays a role in the virulence and fitness of two different EPEC strains, E2348/69 and LRT9. A rpoS null mutation had a small positive effect on LRT9 adherence to epithelial cells, but the expression of the EPEC adhesins BfpA and intimin was not significantly affected by the mutation. E2348/69 adherence was not significantly affected by the rpoS mutation. The intrinsic level of RpoS was higher in LRT9 than in E2348/69 while the latter adhered more strongly and expressed higher levels of the adhesin BfpA than the former. Knockout of rpoS strongly impaired resistance to oxidative, osmotic and acid stress in both E2348/69 and LRT9. However, strain E2348/69 was significantly more sensitive to oxidative stress than LRT9. Finally, competition assays showed that the rpoS mutant of LRT9 displayed higher fitness under continuous culture than its isogenic wild-type strain, while E2348/69 outcompeted its rpoS mutant. In conclusion, RpoS plays mostly a positive role in EPEC biology and at least in the case of strain E2348/69 it is not constrained by the trade-off between vegetative growth and stress resistance.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

RpoS role in virulence and fitness in enteropathogenic Escherichia coli

2017

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“…tive pressures that each result in phenotypically different populations. The idea that intraspecies and interspecies diversities are driven largely by evolutionary trade-offs that arise between different properties of the cell (e.g., biofilm formation, metabolism, motility, stress resistance) when they are subject to the constraints of different environments has recently been reviewed comprehensively (79).…”

Section: Figmentioning

confidence: 99%

The General Stress Response Is Conserved in Long-Term Soil-Persistent Strains of Escherichia coli

Somorin

Abram

Brennan

et al. 2016

Appl Environ Microbiol

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Although Escherichia coli is generally considered to be predominantly a commensal of the gastrointestinal tract, a number of recent studies suggest that it is also capable of long-term survival and growth in environments outside the host. As the extraintestinal physical and chemical conditions are often different from those within the host, it is possible that distinct genetic adaptations may be required to enable this transition. Several studies have shown a trade-off between growth and stress resistance in nutrient-poor environments, with lesions in the rpoS locus, which encodes the stress sigma factor RpoS ( S ). In this study, we investigated a unique collection of long-term soil-persistent E. coli isolates to determine whether the RpoS-controlled general stress response is altered during adaptation to a nutrient-poor extraintestinal environment. The sequence of the rpoS locus was found to be highly conserved in these isolates, and no nonsense or frameshift mutations were detected. Known RpoS-dependent phenotypes, including glycogen synthesis and ␥-aminobutyrate production, were found to be conserved in all strains. All strains expressed the full-length RpoS protein, which was fully functional using the RpoS-dependent promoter reporter fusion PgadX:: gfp. RpoS was shown to be essential for long-term soil survival of E. coli, since mutants lacking rpoS lost viability rapidly in soil survival assays. Thus, despite some phenotypic heterogeneity, the soil-persistent strains all retained a fully functional RpoS-regulated general stress response, which we interpret to indicate that the stresses encountered in soil provide a strong selective pressure for maintaining stress resistance, despite limited nutrient availability. IMPORTANCEEscherichia coli has been, and continues to be, used as an important indicator species reflecting potential fecal contamination events in the environment. However, recent studies have questioned the validity of this, since E. coli has been found to be capable of long-term colonization of soils. This study investigated whether long-term soil-persistent E. coli strains have evolved altered stress resistance characteristics. In particular, the study investigated whether the main regulator of genes involved in stress protection, the sigma factor RpoS, has been altered in the soil-persistent strains. The results show that RpoS stress protection is fully conserved in soil-persistent strains of E. coli. They also show that loss of the rpoS gene dramatically reduces the ability of this organism to survive in a soil environment. Overall, the results indicate that soil represents a stressful environment for E. coli, and their survival in it requires that they deploy a full stress protection response. E scherichia coli is a Gram-negative, facultative anaerobe, belonging to the Enterobacteriaceae family, which inhabits the intestinal tracts of humans, warm-blooded animals, and reptiles (1, 2). It can be transferred through water and sediments via feces and is almost universally used as an i...

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“…Organisms, particularly microbes [26], clearly affect their environments. The existence of trade-offs is widely cited [22,27], as is their importance for competition [7] and possible role in diversity [22,28], albeit modeling of the latter has been limited, e.g., to justifying chaotic population dynamics [29]. We chose to implement metabolic trade-offs via a simple sum rule.…”

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confidence: 99%

Metabolic Trade-Offs Promote Diversity in a Model Ecosystem

2017

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In nature, a large number of species can coexist on a small number of shared resources; however, resource-competition models predict that the number of species in steady coexistence cannot exceed the number of resources. Motivated by recent studies of phytoplankton, we introduce trade-offs into a resource-competition model and find that an unlimited number of species can coexist. Our model spontaneously reproduces several notable features of natural ecosystems, including keystone species and population dynamics and abundances characteristic of neutral theory, despite an underlying non-neutral competition for resources.

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Trade-off Mechanisms Shaping the Diversity of Bacteria

Cited by 161 publications

References 85 publications

RpoS role in virulence and fitness in enteropathogenic Escherichia coli

RpoS role in virulence and fitness in enteropathogenic Escherichia coli

The General Stress Response Is Conserved in Long-Term Soil-Persistent Strains of Escherichia coli

Metabolic Trade-Offs Promote Diversity in a Model Ecosystem

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