Bacillus subtilis Lyt+ and Lyt− strains secrete peptidoglycan hydrolases

Abstract

The phenotypes characteristic of the pleiotropic lytic-deficient Bacillus subtilis mutants have been attributed to reductions in N-acetyl-muramoyl-L-alanine amidase (EC 3.5.1.28) and endo-β-N-acetyl-glucosaminidase (EC 3.2.1.30). It is reported here that these peptidoglycan hydrolases are secreted. The FJ3 (lyt-1), FJ6 (lyt-2), and Nil5 (lyt-15) mutants secreted the enzymes in amounts comparable to a Lyt+ strain. Thus, the Lyt− mutants appear not be as deficient in the enzymes' synthesis as their cell-bound activities indicated. Based on the levels of cell-bound and extracellular activities measured during growth, it is suggested that the Lyt− phenotype may be due to a deficiency of the enzymes' acceptor(s) in cell walls.