Production of Bacillus sphaericus larvicide on industrial peptones

A range of industrial peptones in combination with other carbon and nitrogen sources were investigated in order to define a medium for production of insecticide from Bacillus sphaericus, strain 2362. Industrial protein hydrolysates with an average peptide chain length above 30 were found to be poor substrates. Fermentation of B. sphaericus on protein-based media supplemented with glycerol resulted in production of 4–5x103 units of larvicide per ml fermentation broth, and toxicity of the larvicide up to 104 units per mg. Equally high larvicide production was obtained, when peptone was substituted with 30 mM l-glutamate and 2 mM proline. Addition of 2 mM l-arginine to this medium prevented sporulation and larvicide production.