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Extracellular serine protease synthesis by mosquito-pathogenic strains of Bacillus sphaericus
1Department of Biological Sciences, Heriot-Watt University, Edinburgh, UK.
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.
Insights
Bacillus sphaericus strains toxic to mosquito larvae produce proteases. These bacterial proteases are serine proteases active at alkaline pH and useful for mosquito control.
Area of Science:
- Microbiology
- Biochemistry
- Insect Toxicology
Background:
- Bacillus sphaericus is a bacterium known for its toxicity to mosquito larvae.
- Mosquito-borne diseases pose a significant public health challenge, necessitating effective control strategies.
Purpose of the Study:
- To investigate the protease production and characteristics of Bacillus sphaericus strains toxic to mosquito larvae.
- To identify the type and properties of the extracellular protease synthesized by B. sphaericus BSE 18.
Main Methods:
- Culturing of Bacillus sphaericus strains on casein-nutrient agar to detect hydrolysis zones.
- Batch culture experiments to study protease synthesis regulation.
- Enzymatic assays to determine optimal activity, pH, and inhibition profiles of the extracellular protease.
Main Results:
- Nine B. sphaericus strains exhibited caseinolytic activity, indicating protease production.
- Protease synthesis in B. sphaericus BSE 18 was linked to exponential growth and repressed by high peptone concentrations.
- The extracellular protease displayed optimal activity at pH 10.2, was inhibited by phenylmethylsulphonyl chloride and chymostatin, suggesting it is a serine protease.
Conclusions:
- Bacillus sphaericus strains toxic to mosquito larvae synthesize extracellular proteases.
- The characterized serine protease has alkaline activity and specific inhibition patterns, offering potential for targeted applications in mosquito control.