An N-acetylmuramidase induced by PL-1 phage infection of Lactobacillus casei

A lytic enzyme was isolated and purified from PL-1 phage-induced lysates of the host Lactobacillus casei ATCC 27092. The molecular weight of the enzyme was about 30000. Maximum activity on the lysis of the host cell walls occurred at pH 6.0-6.5 and at 45 degrees C. The enzyme activity was inhibited by heavy metal ions, SH- and serine-enzyme inhibitors and o-phenanthroline. The reducing end of the enzymic digest was muramic acid and the enzyme was considered to be an endo-N-acetylmuramidase. However, the enzyme differed from the other known N-acetylmuramidases including hen's egg-white lysozyme in several enzymic properties.