Starch processing wastewater as a new medium for production of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis>

Production of Bacillus thuringiensis (Bt) based bioinsecticide was studied by using starch processing wastewater (SPW) as a raw material. Results indicated that the nutrients contained in SPW were sufficient for growth, sporulation and δ-endotoxin production of Bacillus thuringiensis subsp. kurstaki (Btk). The final cell counts and spore counts achieved in SPW medium were 72% and 107% respectively higher than those in the soybean meal based commercial medium. Higher δ-endotoxin yield of 2.67 mg mL⁻¹ and higher entomotoxicity of 1,050 IU μL⁻¹ were also obtained in SPW medium as compared with the commercial medium at the end of fermentation. The morphological observations also revealed that the fermentation cycle of Btk could be shortened in this new medium. This process provides solutions for safe SPW disposal and production of high potency and low cost bioinsecticide.