[Heterogeneity of Escherichia coli population during induced autolysis]

Escherichia coli M-17 autolysis was induced by eliminating nutrition sources from the growth medium and exerting a shock with EDTA. The overall cell number, the optical density of the cell suspension, the number of colony-forming units (CFU), and [3H]uracil incorporation into the cells were analysed in the course of autolysis. The number of CFU was found to drop down faster than the overall cell number in the process of autolysis. The population of E. coli was shown to be heterogeneous in its sensitivity to the induction of autolysis, and some nonlysed cells were still metabolically active. When the rate of autolysis was highest in some cells of the population, the labeled precursor was found to be incorporated into the TCA-soluble and TCA-insoluble fractions of nonlysed cells. The overall cell number, the optical density of the cell suspension, and the number of CFU increased 96 h after the induction of autolysis. The authors discuss what is the role played by the heterogeneity of an E. coli population in its adaptation to EDTA-induced autolysis.