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 x 10(x) spores/ml. SDS-PAGE analysis of spore-crystal protein produced during the fermentation indicated a molecular weight of approximately 135 000, 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.