[The effect of substrates and irradiation with low intensity visible light on the rate of division of Escherichia coli].

The effect of He--Ne laser irradiation (lambda = 632.8 nm, D = 4.10(3) J/m2) on the growth of Escherichia coli cultures was studied in a minimal medium containing glucose, glycerol of arabinose. The irradiated cultures immediately started to divide with a virtually identical specific growth rate (kappa = 0.78, 0.8 and 0.8 h-1) whatever the growth rate and the latent period of the parent cultures were. The ratio between cell numbers in the irradiated and non-irradiated cultures was highest 1 h after the irradiation: 1.25, 1.3 and 1.5 for the glucose, glycerol and arabinose cultures, respectively. Apparently, the irradiation with visible light of a low intensity creates an additional proton gradient and thus stimulates a new replication and division cycle in the population of cells whose membranes do not have delta pH necessary for the initiation of these processes. The system under study can serve as a model for studying the delta pH-dependent stages in the regulation of cell division.