Involvement of Autolysis of Cytoplasmic Membranes in the Process of Autolysis of Bacillus cereus

SUMMARY: When exponentially growing Bacillus cereus organisms were suspended in buffer or buffered hypertonic sucrose solution and incubated at 37°, a rapid decrease in turbidity of the suspension was observed (autolysis). During autolysis ultraviolet-absorbing substances leaked from the bacteria and over 50% of the total phospholipids was released. Of the amino sugars, main components of the cell walls of this organism, less than 20% was released. Phase-contrast microscopy showed the empty rod-shaped ghosts which increased in number, while the total counts were constant during autolysis.

Mg2+ and Mn2+ inhibited the autolysis; these cations either prevented leakage of ultraviolet absorbing substances or release of phospholipids. Isolated cytoplasmic membranes autolysed when the membranes were incubated at 37° in buffer solution (pH 7.0 to 7.5). It could be assumed, therefore, that the cytoplasmic membranes of Bacillus cereus were lysed faster than the cell walls during autolysis and that the autolysis of the membranes was inhibited by Mg2+ and Mn2+.