Morphological and physiological study of autolytic-defective Streptococcus faecium strains

Abstract

Autolytic-defective mutants (3) of S. faecium (S. faecalis ATCC 9790) were isolated. All 3 autolytic-defective mutants exhibited the following properties relative to the parental strain: slower growth rates, especially in chemically defined medium; decreased rates of cellular autolysis and increased survival after exposure to antibiotics which block cell wall biosynthesis; decreased rates of cellular autolysis when treated with detergents, suspended in autolysis buffers or grown in medium lacking essential cell wall precursors; a reduction in the total level of autolytic enzyme (active plus latent forms of the enzyme); an increased ratio of latent to active forms of autolysin; and increased levels of cellular lipoteichoic acid and lipids.