4. Conclusions
(1) Food waste contains comprehensive nutrition and is suitable for Bt production;
(2) Compared with solid-state and submerged fermentation, semi-solid state fermentation has better δ-endotoxin production and presents considerable advantages;
(3) The inoculum size, the initial pH, the oil content and the salt content had different influence in semi-solid state fermentation, when the four factors adjusted to the best level, δ-endotoxin produced the highest yield of 2310 ug/mL and entomotoxicity arrived to 56875IU/mg;
(4) The study provided a new way for the industrialization of Bacillus thuringiensis biopesticide