Study on Influence Factors in Bacillus Thuringiensis Production by Semi-solid State Fermentation Using Food Waste

Abstract

Bacillus thuringiensis(Bt) bio-pesticides is a kind of selective and efficient pesticides, but the high cost of raw materials always limits its development, food waste contains superior nutritional elements which could sustain the growth of most microorganisms. So we choose food waste as the material, explored its feasibility of producing bio-pesticides and optimized the influence parameters during the fermentation process. In this work, food waste with 75% water content presented δ-endotoxin efficiency of 862μg/mL, spore count of 2.23×1011 CFU/mL and entomotoxicity of 56560 IU/mg. The influence factors during fermentation process were optimized by asingle-factor indextest, and the result showed that initial pHhad a max effect on the fermentation performance. The optimum fermentation conditions were0.2% inoculum size, 2% salt content, 5% or less oil content, and the initial pH adjusted to 7.0, inoptimized conditions, the δ-endotoxin outputwas2310μg/mL and the entomotoxicity was 56875IU/mgafter fermentation. It seemed to be a promising way to make use of food waste.