A medium containing cornsteep liquor (CSL) as a replacement for yeast extract (YE) enhanced the sporulation of Bacillus sphaericus 2362. Fed-batch culture with combinations of YE and CSL together with acetate as carbon source resulted in a cell mass of 13.0 g/L and a high spore count of 16.4 X 10(9)/mL. This compared to an acetate, YE based medium which produced a similar cell concentration but only 4 X 10(9) spores/mL. Western blot analysis indicated significant toxin production in the former case.