CELL-WALL AND AUTOLYTIC SYSTEM OF LACTOBACILLUS-HELVETICUS ATCC-12046

The cell wall of Lactobacillus helveticus was found to have a three-layered structure when thin sections of whole cells or isolated cell walls were stained by various procedures and examined by electron microscopy. The main feature of the composition of isolated cell walls was a high protein content (about 48% of the cell wall dry weight) with a predominant 52 kDa protein. Peptidoglycan and what was considered as teichoic acids accounted for 36% and 14%, respectively, of the cell wall dry weight. The 52 kDa protein was apparently unglycosylated, located in the outer layer and noncovalently bound to the inner layers. Peptidoglycan was mostly assigned to the innermost layer. The conditions leading to autolysis of whole cells or isolated cell walls were determined, as well as the specificity of the autolysin involved in cell wall degradation.