Open AccessInvestigation of the First Events Leading to Loss of Culturability during Escherichia coli Starvation: Future Nonculturable Bacteria Form a Subpopulation
Author(s) -
C. Cuny,
Laure Dukan,
Laetitia Fraysse,
Manuel Ballesteros,
Sam Dukan
Publication year - 2005
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.187.7.2244-2248.2005
Subject(s) - rpos , biology , escherichia coli , bacteria , microbiology and biotechnology , viable but nonculturable , superoxide dismutase , population , enterobacteriaceae , reactive oxygen species , hydrogen peroxide , oxidative stress , biochemistry , gene expression , genetics , promoter , demography , sociology , gene
In previous experiments we were able to separate, using a nondestructive separation technique, culturable and nonculturable bacteria, from a Luria-Bertani (LB) medium culture of Escherichia coli incubated for 48 h. We observed in the nonculturable bacterial population an increase in oxidative damage and up-induction of most defenses against reactive oxygen species (ROS), along with a decrease in cytoplasmic superoxide dismutases. In this study, using the same separation technique, we separated into two subpopulations a 10-h LB medium culture containing only culturable bacteria. For the first time, we succeeded in associating physical separation with physiological differences. Although the levels of defense against ROS (RpoS, RpoH, OxyR, and SoxRS regulons) and oxidative damage (carbonyl contents) were apparently the same, we found that bacteria in one subpopulation were more sensitive to LB medium starvation and to various stresses, such as phosphate buffer starvation, heat shock, and hydrogen peroxide exposure. Based on these results, we suggest that these physiological differences reflect uncharacterized bacterial modifications which do not directly involve defenses against ROS.