Persister cells are metabolically quiescent multi-drug tolerant fraction of a genetically sensitive bacterial population and are thought to be responsible for relapse of many
persistent infections. Persisters can be formed naturally in the stationary phase culture, and also can be induced by bacteriostatic
antibiotics. However, the molecular basis of bacteriostatic
antibiotic induced persister formation is unknown. Here, we established a bacteriostatic
antibiotic induced persister model and screened the Escherichia coli single gene deletion mutant library for mutants with defect in
rifampin or
tetracycline induced persistence to
ofloxacin. Thirsty-seven and nine genes were found with defects in
rifampin- and
tetracycline-induced persister formation, respectively. Six mutants were found to overlap in both
rifampin and
tetracycline induced persister screens: recA, recC, ruvA, uvrD, fis, and acrB. Interestingly, four of these mutants (recA, recC, ruvA, and uvrD) mapped to DNA repair pathway, one mutant mapped to global transcriptional regulator (fis) and one to efflux (acrB). The stationary phase culture of the identified mutants and parent strain BW25113 were subjected to different
antibiotics including
ofloxacin,
ampicillin,
gentamicin, and stress conditions including
starvation and
acid pH 4.0. All the six mutants showed less tolerance to
ofloxacin, but only some of them were more sensitive to other specific stress conditions. Complementation of five of the six common mutants restored the persister level to that of the parent strain in both stationary phase and static
antibiotic-induced conditions. In addition to the DNA repair pathways shared by both
rifampin and
tetracycline induced persisters, genes involved in
rifampin-induced persisters map also to transporters, LPS biosynthesis, flagella biosynthesis, metabolism (
folate and energy), and translation, etc. These findings suggest that persisters generated by different ways may share common mechanisms of survival, and also shed new insight into the molecular basis of static
antibiotic induced antagonism of cidal
antibiotics.