Induction and control of the autolytic system of Escherichia coli

Abstract

Various methods of inducing autolysis of E. coli cells were investigated, some being described for the first time. For the autolysis of growing cells, only induction methods interfering with the biosynthesis of peptidoglycan were taken into consideration, whereas with harvested cells autolysis was induced by rapid osmotic or EDTA shock treatments. The highest rates of autolysis were observed after induction by moenomycin, EDTA or cephaloridine. The different autolyses examined shared certain common properties. In particular, regardless of the induction method used, more or less extensive peptidoglycan degradation was observed, and 10-2 M Mg2+ efficiently inhibited the autolytic process. For other properties, a distinction was made between methods used for growing cells and those used for harvested cells. Autolysis of growing cells required RNA, protein and fatty acid synthesis. No such requirements were observed with shock-induced autolysis performed with harvested cells. The effects of Mg2+, rifampicin, chloramphenicol and cerulenin clearly suggest that distinct factors are involved in the control of the autolytic system of E. coli. Uncoupling agents such as sodium azide, 2,4-dinitrophenol and carbonyl-cyanide-m-chlorophenyl hydrazone used at their usual inhibiting concentration had no effect on the cephaloridine or shock-induced autolysis.