Production of intracellular serine protease during sporulation of Bacillus brevis ATCC9999

Abstract

It has been reported (Slapikoff et al. 1971) that Bacillus brevis ATCC9999, the producer of gramicidin S, makes no extracellular or intracellular protease in complex medium which supports sporulation. We have found that intracellular protease is made by this strain; however, the activity requires the presence of the reducing agent dithiothreitol in the extraction buffer. B. brevis intracellular protease appears at the time that refractile spores are visible in the mother cells. Its pH optimum is 8.0. The enzyme is inhibited by ethylenediaminetetraacetic acid and phenylmethylsulfonylfluoride but not by o-phenanthroline, boronic acids, and only slightly by p-chloromercuribenzoate. This inhibitor pattern is similar to that of intracellular proteases of B. megaterium and B. subtilis, classifying the B. brevis protease as an intracellular seryl protease.