Fermentation Conditions for High Toxicity Bt Isolates against Ephesia elutella Hübner

The fermentation conditions of Bt33、Bt53、BtHB isolates of Bacillus thuringiensis, which were high toxicity to Lepidoptera insect, were studied.The results indicated that the optimum culture conditions for all tested isolates were:30℃, pH 7.5, rotating speed 180 rpm.The optimum culture time for Bt33 and Bt53 isolates was 40 hours, while that for BtHB was 36 hours.And the optimum air volume for Bt33 and Bt53 isolates was 9/10 (container volume-medium volume/container volume), while that for BtHB was 19/20.