Autolysis of dairy leuconostocs and detection of peptidoglycan hydrolases by renaturing SDS-PAGE

The autolysis of lactic acid bacteria plays a major role during cheese ripe ning. The aim of this study was to evaluate the autolytic properties and pe ptidoglycan hydrolase content of dairy leuconostocs. Autolysis of 59 strain s of dairy Leuconostoc was examined under starvation conditions in potassiu m phosphate buffer. The ability of dairy leuconostocs to lyse is strain dep endant and not related to the species. The peptidoglycan hydrolase profile of Leuc. mesenteroides subsp. mesenteroides 10L was analysed by renaturing gel electrophoresis. Two major activity bands migrating at 41 and 52 kDa we re observed. According to the specificity analysis, strain 10L seems to con tain a glycosidase and an N-acetyl-muramyl-l-alanine amidase, or an endopep tidase. The peptidoglycan hydrolase profiles of various Leuconostoc species were also compared. Several peptidoglycan hydrolase activities could be de tected in the different Leuconostoc species. Further characterization of th e peptidoglycan hydrolases will help to control autolysis of leuconostocs i n cheese.