Abstract
The addition of 1-alkanols to exponentially growing cultures of Bacillus subtilis led to an immediate reduction in growth rate and a rapid reduction in the rate of autolysis of cells in suspension. 1-Alkanols had no effect on autolysis when added to the non-growing suspensions. The effects were proportional to the concentrations added to cultures and to the lengths of the carbon chains up to octanol. The growth rate was immediately restored to that of the control when 0·7 m-ethanol was removed from cultures but the rate of cell autolysis only fully recovered after two to three generations. Ethanol (0·7 m) protected the organism against lysis and the bactericidal effects of β-lactam antibiotics; leakage of the intracellular pool was also greatly reduced. Despite some properties in common with the phenotype of lyt mutants or of cultures treated with cerulenin, the individual bacteria separated well, and were of normal shape and highly motile. Turnover of the walls was only slightly affected. Protein synthesis was not specifically inhibited but export of proteins was increased and included the appearance of novel proteins. Peptidoglycan synthesis was less affected than growth; after 3 h about twice as much peptidoglycan was present per unit of dry weight compared with control cultures. It seems unlikely that ethanol inhibited synthesis of autolytic enzymes although less activity could usually be extracted from the cells by 5 m-LiCl, since treatment with very low concentrations of neutral detergents reactivated cell autolysis. The walls of ethanol-grown cells were fully susceptible to autolytic enzymes.