期刊
MICROBIAL ECOLOGY
卷 83, 期 1, 页码 68-82出版社
SPRINGER
DOI: 10.1007/s00248-021-01751-6
关键词
RpoS; Trade-offs; Stress resistance; Polymorphism; Escherichia coli; Natural isolates
资金
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)
- CAPES research scholarship
- FAPESP M.Sc. scholarship
A trade-off between reproduction and survival is common in many organisms, with Escherichia coli featuring RpoS as a key factor in this balance. Studying strains in a natural environment, it was found that RpoS levels vary widely, leading to a diverse range of stress resistance responses in E. coli strains.
A trade-off between reproduction and survival is a characteristic of many organisms. In bacteria, growth is constrained when cellular resources are channelled towards environmental stress protection. At the core of this trade-off in Escherichia coli is RpoS, a sigma factor that diverts transcriptional resources towards general stress resistance. The constancy of RpoS levels in natural isolates is unknown. A uniform RpoS content in E. coli would impart a narrow range of resistance properties to the species, whereas a diverse set of RpoS levels in nature should result in a diverse range of stress susceptibilities. We explore the diversity of trade-off settings and phenotypes by measuring the level of RpoS protein in strains of E. coli cohabiting in a natural environment. Strains from a stream polluted with domestic waste were investigated in monthly samples. Analyses included E. coli phylogroup classification, RpoS protein level, RpoS-dependent stress phenotypes and the sequencing of rpoS mutations. The most striking finding was the continuum of RpoS levels, with a 100-fold range of RpoS amounts consistently found in individuals in the stream. Approximately 1.8% of the sampled strains carried null or non-synonymous mutations in rpoS. The natural isolates also exhibited a broad (>100-fold) range of stress resistance responses. Our results are consistent with the view that a multiplicity of survival-multiplication trade-off settings is a feature of the species E. coli. The phenotypic diversity resulting from the trade-off permits bet-hedging and the adaptation of E. coli strains to a very broad range of environments.
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