Abstract: Feasibility of combined fermentation of sewage sludge and waste molasses to ?Bacillus thuringiensis? based biopesticide was studied. As a kind of useful supplemental carbon sources, waste molasses proved to be effective in promoting the growth and metabolism of ?Bacillus thuringiensis? when the additive proportion was lower than 2.0%. Excessive molasses delayed the fermentation process and restrained the spores or crystals from maturing. The best combined medium was found to be sewage sludge (3% total solid) supplemented with 1.5 % molasses (w/w). In this medium, the highest viable cells count (VC) and viable spores count (VS) could rise up to 4.17×10⁸CFU?mL^-1and 3.60×10⁸CFU?mL^-1, respectively. Both crystal protein concentration and entomotoxicity of this medium were also superior to other combined media at the end of fermentation, with the highest crystal protein yield of 1.96 mg?mL^-1 and entomotoxicity of 788 IU?μL^-1, respectively. Moreover, significant correlation can be seen between the crystal protein yield and the entomotoxicity. Therefore, crystal protein yield can be used as a simple but reliable index for assessing the Bt fermentation process.

Key words: sewage sludge, waste molasses, crystal protein, entomotoxicity

摘要： 考察了城市污泥与废糖蜜联合发酵培养苏云金芽孢杆菌（Bt）生物杀虫剂的可行性。作为污泥发酵的补充碳源，废糖蜜添加比例低于2.0%（质量比）时，对Bt的生长、代谢、晶体蛋白合成以及毒效有良好的促进作用，当添加比例高于2.0%时则表现出抑制作用。通过改变废糖蜜添加比例，获得污泥与废糖蜜的最佳配比：即在含固率为3%的污泥中添加1.5%（质量比）的废糖蜜。此配比对Bt生长代谢最为有利，活菌数与活芽孢数最大值可分别达到4.17×10⁸和3.60×10⁸CFU?mL^-1，发酵48 h后，发酵液中晶体蛋白产量约为1.96 mg?mL^-1，毒效788 IU?μL^-1，高于其他复配培养基。此外，本研究表明，晶体蛋白产量与发酵液生物毒效有显著相关性，晶体蛋白含量可作为一种简单可靠的Bt发酵性能表征指标，在Bt生产中有一定实用价值。

关键词: 城市污泥, 废糖蜜, 晶体蛋白, 杀虫毒效