Hyper-autolysis of the Facultative AlkaliphileBacillussp. C-125 Cells Grown at Neutral pH: Culture-pH Dependent Cross-linking of the Peptide Moieties of the Peptidoglycan

Abstract

The cells of the facultative alkaliphile Bacillus sp. C-125 grown at neutral pH autolyzed rapidly in alkaline buffers of pH 9–10. By contrast, the cells grown at alkaline pH were apparently stable under the same conditions. Alkaline N-acetylmuramyl-l-alanine amidase associated with the cell walls caused this alkali-instability. Meanwhile, cross-linkage between peptide moieties of the peptidoglycan of the organism was dependent on the culture pH. The cross-linking rate was low (31%) in the peptidoglycan of the cells grown at neutral pH, and high (52%) in the cells grown at alkaline pH. This low linking rate is one of the reasons why the cells grown at neutral pH were unstable at alkaline pH. The high linkages in the peptidoglycan might be a cellular adaptation of the organism for growth in alkaline environments.