Bacillus thuringiensis subsp. kurstaki spore production in batch culture using broiler litter extracts as complex media

Broth for the growth of Bacillus thuringiensis subsp. kurstaki was prepared by extraction of broiler litter with water. Filamentous growth occurred during the first 6 h of fermentation in the full strength and in a 2:1 extract dilution. Of the five dilutions examined, the 2:1 dilution of the extract having a total organic carbon concentration of 1.7 g/l produced the highest spore count, 2.46 × 108 spores/ml. SDS-PAGE analysis of spore-crystal protein produced during the fermentation indicated a molecular weight of approximately 135000, suggesting the presence of bacterial insecticidal protoxin. With appropriate pretreatment, broiler litter may be a valuable resource when used as a low-cost complex medium for production of biochemicals.