Production and characterization of a thermostable protease produced by an asporogenous mutant of Bacillus stearothermophilus

Abstract

An asporogenous mutant of Bacillus stearothermophilus (TPM-8) which produces 4-fold higher levels of a thermostable neutral protease than does wild-type strain 308-1 was obtained by mutagenesis with ethyl methanesulfonate. The protease produced by both the mutant and wild-type strain is a metalloprotease requiring Zn2+ and Ca2+ for activity and thermostability, respectively. It has a temperature optimum of 80°C at pH 7.0 and is highly thermostable, retaining 60% of its activity after 60 min at 85°C. The properties of the enzyme are similar to those of thermolysin. © 1990 Society for Industrial Microbiology.