Evidence for Coexistence of Distinct Escherichia coli Populations in Various Aquatic Environments and Their Survival in Estuary Water

Abstract

b Escherichia coli, a commensal bacterium from the intestinal tracts of humans and vertebrate animals, has been used as one of two bacterial indicators of fecal contamination, along with intestinal enterococci, to monitor the microbiological quality of water. However, water environments are now recognized as a secondary habitat where some strains can survive. We investigated the survival of E. coli isolates collected from bodies of water in France exhibiting distinct profiles of contamination, defined according to the following criteria: vicinity of the point sources of contamination, land use, hydrology, and physicochemical characteristics of the receiving water. We selected 88 E. coli strains among a collection of 352 strains to carry out a microcosm experiment in filtered estuarine water for 14 days at 10°C. The relationship between the survival of E. coli strains and genotypic and phenotypic characteristics was analyzed. This work showed that distinct E. coli survival types, able to survive from between 7 and 14 days to less than 2 days, coexisted in the water. E. coli isolates that rapidly lost their culturability were more frequently isolated in water recently contaminated by fecal bacteria of human origin, and most were multiresistant to antibiotics and harbored several virulence factors. In contrast, persistent strains able to survive from 4 to 14 days were more often found in water with low levels of fecal bacteria, belonged mainly to the B1 phylogroup, often harbored only one virulence factor, kspE or ompT, and were able to grow at 7°C.

Effect of Environmental Conditions on <i>Escherichia coli</i> Survival in Seawater

“…This suggested the importance of cell strain and origin to their survival in sea water and partially contributed to better understanding of the variations in results of previous studies. Since all tested E. coli strains were exposed to the same environmental conditions, the obtained results probably illustrated the extensive genetic and phenotypic diversity exhibited within E. coli strains, which could explain the different survival abilities in this study and aquatic environments generally [31]. On the basis of genomic information, E. coli species have been divided into eight phylogenetic groups, A, B1, B2, C, D, E, F, and clade I [32].…”

“…Significant differences in survival in water environment were found among strains belonging to different phylogroups. Recent studies showed that E. coli B1 strains can persist longer in water than strains of the other phylogroups [31] and supported the hypothesis that persistent genotypes have an adaptive advantage in the secondary habitat outside the host [35]. Consequently, once released into water, E. coli strains could be selected on the basis of their survival ability, and the resulting population differed from the original one in terms of phenotypic traits.…”

Change in the Structure of Escherichia coli Population and the Pattern of Virulence Genes along a Rural Aquatic Continuum

“…Once released in water, the population structure of E. coli can be modified: it reflects both their primary host and their fate in this environment (Berthe et al, 2013; Chandran and Mazumder, 2015). In environmental water, spatial and seasonal changes of the E. coli population diversity have been demonstrated using fingerprinting methods (Chandran and Mazumder, 2015).…”

A cis‐acting antitoxin domain within the chromosomal toxin–antitoxin module EzeT of Escherichia coli quenches toxin activity

“…Notably, phylogroup B1 isolates are predominantly found in locations with ambient temperature, e.g. soil (Walk et al ., ), on plants (Meric et al ., ), in the gastrointestinal tract of ectotherms (Gordon and Cowling, ), and show prolonged survival times outside the host (Berthe et al ., ). Strikingly, we found that EzeT toxicity is temperature‐dependent and activity is highest at low temperature as described earlier for the GraTA system from the soil bacterium Pseudomonas putida (Tamman et al ., ).…”