Solid-state Fermentation of Kitchen Waste for Production of Bacillus thuringiensis-based Bio-pesticide

Abstract

In this work, kitchen waste was used as substrate for bio-pesticide production by solid-state fermentation. It was assessed to be well suited for the growth of Bacillus thuringiensis in the experiments. The culture medium contents were optimized by an orthogonal test. The optimum mixture was 55.21% kitchen waste, 22.08% wheat bran, 11.04% soybean cake power, 11.04% grain hulls, and 0.63% mixed ions. In the optimized conditions, a spore count of 5.01 × 1010 CFU/g and entomotoxicity of 15200 IU/mg were obtained after 48 h fermentation, while 2.51 × 1010 CFU/g spore count and 12900 IU/mg entomotoxicity were obtained from the conventional medium. Oil and salt had few adverse effects on Bacillus thuringiensis growth, yield of spores, and toxicity when the concentration of oil and salt were controlled below 10% and 0.4% to 1.2%, respectively. Fermentation medium of 35 kg was successfully used to produce bio-pesticides from solid-state fermentation in a scale-up experiment. Therefore, the present study proved the feasibility of using kitchen waste for the production of bio-pesticides. It seemed to be a promising alternative to conventional media to reduce costs.