Bacteriocin expression in sessile and planktonic populations of Escherichia coli

Majeed, Hadeel A.; Ghazaryan, Lusine; Herzberg, Moshe; Gillor, Osnat

doi:10.1038/ja.2014.84

Cited by 11 publications

(14 citation statements)

References 18 publications

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“…For ColE7, the same study determined 1.5% GFP + cells in the early stationary phase. In a different study using the same gfp -reporter, comparable levels were determined in the stationary phase and slight increases were observed at post-exponential (1.8±0.2%) and exponential phase (2.3±1.2) [ 16 ]. For ColK, 3% of the E .…”

Section: Resultsmentioning

confidence: 99%

“…Besides nutrient conditions, other environmental cues can also affect colicin expression. For example, comparison of ColE7 expression in biofilm and planktonic environments revealed a two to three-fold upregulation in biofilms [ 16 ]. Thus, signals derived from DNA damage, growth conditions and the nutritional status of the bacteria converge to regulate colicin expression.…”

Section: Introductionmentioning

confidence: 99%

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Reporters for Single-Cell Analysis of Colicin Ib Expression in Salmonella enterica Serovar Typhimurium

Spriewald¹,

Glaser

Beutler³

et al. 2015

PLoS ONE

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Colicins are toxins that mediate interference competition in microbial ecosystems. They serve as a “common good” for the entire producer population but are synthesized by only few members which pay the costs of colicin production. We have previously shown that production of colicin Ib (cib), a group B colicin, confers a competitive advantage to Salmonella enterica serovar Typhimurium (S. Tm) over commensal E. coli strains. Here, we studied regulation of S. Tm cib expression at the single cell level. Comparative analysis of a single- and a multicopy gfp-reporter for the colicin Ib promoter (Pcib) revealed that the latter yielded optimal signal intensity for a diverse range of applications. We further validated this reporter and showed that gfp expression correlated well with colicin Ib (ColIb) protein levels in individual cells. Pcib is negatively controlled by two repressors, LexA and Fur. Only a small fraction of S. Tm expressed cib under non-inducing conditions. We studied Pcib activity in response to mitomycin C mediated DNA damage and iron limitation. Both conditions, if applied individually, lead to an increase in the fraction of GFP+ S. Tm, albeit an overall low fluorescence intensity. When both conditions were applied simultaneously, the majority of S. Tm turned GFP+ and displayed high fluorescence intensity. Thus, both repressors individually confine cib expression to a subset of the population. Taken together, we provide the first thorough characterization of a conventional gfp-reporter to study regulation of a group B colicin at the single cell level. This reporter will be useful to further investigate the costs and benefits of ColIb production in human pathogenic S. Tm and analyze cib expression under environmental conditions encountered in the mammalian gut.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reporters for Single-Cell Analysis of Colicin Ib Expression in Salmonella enterica Serovar Typhimurium

Spriewald¹,

Glaser

Beutler³

et al. 2015

PLoS ONE

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“…Inconsistency between competition outcomes in liquid cultures and on plate culture observed in our study suggests that benefits of interference on a surface is relaxed in liquid culture, where the bacterial cells are more likely to have less frequent contact with competitor cells, and the toxins are subjected to dilution. This indicates different trajectories of competition strategies depending whether the cells live in biofilm or in a planktonic state 26, 27 . Toxins are, indeed, commonly released in surfaces (such as biofilm) in which bacterial populations are dense and consequently nutrient limited 28 .…”

Section: Discussionmentioning

confidence: 99%

Application of high resolution melting assay (HRM) to study temperature-dependent intraspecific competition in a pathogenic bacterium

Ashrafi

Bruneaux

Sundberg

et al. 2017

Sci Rep

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Studies on species’ responses to climate change have focused largely on the direct effect of abiotic factors and in particular temperature, neglecting the effects of biotic interactions in determining the outcome of climate change projections. Many microbes rely on strong interference competition; hence the fitness of many pathogenic bacteria could be a function of both their growth properties and intraspecific competition. However, due to technical challenges in distinguishing and tracking individual strains, experimental evidence on intraspecific competition has been limited so far. Here, we developed a robust application of the high-resolution melting (HRM) assay to study head-to-head competition between mixed genotype co-cultures of a waterborne bacterial pathogen of fish, Flavobacterium columnare, at two different temperatures. We found that competition outcome in liquid cultures seemed to be well predicted by growth yield of isolated strains, but was mostly inconsistent with interference competition results measured in inhibition tests on solid agar, especially as no growth inhibition between strain pairs was detected at the higher temperature. These results suggest that, for a given temperature, the factors driving competition outcome differ between liquid and solid environments.

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“…The prevailing model of colicin production asserts that colicinogenic populations are heterogeneous, as a small subset expresses large amounts of colicin, which increase during induction 17 19 20 22 23 . Phenotypic heterogeneity disperses expression costs among members of the clonal population and has been reported in bacteriocins produced by Bacillus subtilis 31 , Streptococcus mutans 32 and Streptococcus pneumoniae 33 .…”

Section: Discussionmentioning

confidence: 99%

“…Another measure suggested to compensate for the cost associated with production colicins is the ‘division of labor’ as only a very small fraction of the population express colicin, whereas most of the cells silence expression, suggesting phenotypic heterogeneity 17 . Studies evaluating the number of producers of various colicin types revealed that, under specific environmental conditions 18 , 0.5–3% of planktonic E. coli populations and 7–9% of sessile populations produce colicins 19 20 21 . Stochastic expression of colicins in monoclonal populations has been shown to be regulated by the SOS response system 22 23 , suggesting that random mutations induce the DNA-repair system, which triggers colicin expression.…”

mentioning

confidence: 99%

Bet-hedging in bacteriocin producing Escherichia coli populations: the single cell perspective

Bayramoglu

Toubiana

Vliet

et al. 2017

Sci Rep

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Production of public goods in biological systems is often a collaborative effort that may be detrimental to the producers. It is therefore sustainable only if a small fraction of the population shoulders the cost while the majority reap the benefits. We modelled this scenario using Escherichia coli populations producing colicins, an antibiotic that kills producer cells’ close relatives. Colicin expression is a costly trait, and it has been proposed that only a small fraction of the population actively expresses the antibiotic. Colicinogenic populations were followed at the single-cell level using time-lapse microscopy, and showed two distinct, albeit dynamic, subpopulations: the majority silenced colicin expression, while a small fraction of elongated, slow-growing cells formed colicin-expressing hotspots, placing a significant burden on expressers. Moreover, monitoring lineages of individual colicinogenic cells showed stochastic switching between expressers and non-expressers. Hence, colicin expressers may be engaged in risk-reducing strategies—or bet-hedging—as they balance the cost of colicin production with the need to repel competitors. To test the bet-hedging strategy in colicin-mediated interactions, competitions between colicin-sensitive and producer cells were simulated using a numerical model, demonstrating a finely balanced expression range that is essential to sustaining the colicinogenic population.

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Bacteriocin expression in sessile and planktonic populations of Escherichia coli

Cited by 11 publications

References 18 publications

Reporters for Single-Cell Analysis of Colicin Ib Expression in Salmonella enterica Serovar Typhimurium

Reporters for Single-Cell Analysis of Colicin Ib Expression in Salmonella enterica Serovar Typhimurium

Application of high resolution melting assay (HRM) to study temperature-dependent intraspecific competition in a pathogenic bacterium

Bet-hedging in bacteriocin producing Escherichia coli populations: the single cell perspective

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