EXTRACELLULAR SERINE-PROTEASE SYNTHESIS BY MOSQUITO-PATHOGENIC STRAINS OF BACILLUS-SPHAERICUS

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