[Characteristics of the autoregulatory factor d2 causing autolysis of Pseudomonas carboxydoflava and Bacillus cereus cells].

In the course of organoheterotrophous growth, Pseudomonas carboxydoflava Z-1107 and Bacillus cereus 504 were found to synthesize the autoregulatory factor d2, a membranotropic lipid metabolite, and to accumulate it in the growth medium. At a low concentration, the factor activated respiration of the cells: at a high concentration, it inhibited respiration and induced autolysis of the cells. The physiological action of d2 was shown to be due to the effect of free fatty acids, in particular, palmitic, stearic and oleic acids. Oleic acid displayed the highest physiological activity, P. carboxydoflava Z-1107 became more susceptible to high concentrations of d2 and oleic acid, and respiration of the cells was activated by low concentration of these compounds when the culture passed from the exponential growth phase to the linear one. These results as well as data reported in literature about the action of fatty acids on biological membrane suggest that low concentrations of the factor d2 uncouple respiration and oxidative phosphorylation whereas high concentrations of the factor disorganize the structure of the cytoplasmic membrane by increasing its fluidity.