Effect of sigma(S) on sigma(E)-directed cell lysis in Escherichia coli early stationary phase

The sigma(E) regulon has been shown to perform a novel function that causes dead-cell lysis specific to the early stationary phase [Nitta et al., 2000] in addition to its well-known role in the extracytoplasmic stress response in Escherichia coli. Here, the effect of us as a general stress-responsive sigma factor on sigma(E)-directed cell lysis was investigated. The lysis phenomena were observed in both rpoS mutant and parental strains constitutively expressing active sigma(E), but the former lysis occurred at a relatively early stage compared to the latter. Based on these results and experiments with hydrogen peroxide, we propose that some stresses generate living but non-culturable cells, which are subject to sigma(E)-directed cell lysis. Copyright (C) 2004 S. Karger AG, Basel.