Extracellular serine protease synthesis by mosquito-pathogenic strains of Bacillus sphaericus.

Abstract

Nine strains of Bacillus sphaericus toxic to mosquito larvae produced haloes of hydrolysis when cultured on casein-nutrient agar. In batch culture, protease synthesis by B. sphaericus BSE 18 occurred during exponential growth and was repressed by high concentrations of peptone. Extracellular protease from this bacterium showed optimal activity at about pH 10.2, was inhibited by phenylmethylsulphonyl chloride and chymostatin but not soybean trypsin inhibitor or EDTA. Hydrolysis of N-CBZ-glycine-nitrophenyl ester was consistent with the major enzyme being a serine protease.