红三叶鲜青草预加工废水是在提取红三叶草中的异黄酮时产生的废水,含有大量的糖、蛋白质等有机质,可作为净化废水的材料而被充分利用。实验以红三叶鲜青草预加工废水为原料,采用Plackett-Burman设计(PBD)、最陡爬坡设计(SAD)和Box-Behnken设计(BBD)等实验方法,对利用红三叶草预加工废水发酵培养苏云金芽孢的条件进行了研究。结果显示:红三叶草废水经预处理、热处理和去除沉淀物后,添加3.08 g/L(NH4)2SO4、1.0 g/L KH2PO4、0.25 g/L MgSO4、0.15 g/L CaCl2和0.50 g/L MnSO4,可制得苏云金芽孢杆菌液体发酵培养基。利用该发酵培养基,在起始pH 7.3、温度30℃和接种量7.5%(v/v)的条件下,发酵培养苏云金芽孢杆菌66.7 h,苏云金芽孢杆菌菌体生物量可达8.75 g/L,是基础发酵培养基产生生物量的1.2倍。

Red clover preprocessing wastewater is generated from extraction of the isoflacones from dry red clover by squeezing and washing.The wastewater includes a lot of sugar,protein and other organic matter that can be well used as the materials to purify wastewater.In this paper,we used the fresh red clover processing wastewater as the materials and a series of experimental designs,including Plackett-Burman design(PBD),the steepest ascent design(SAD) and Box-Behnken design(BBD) to optimize the cultivation and fermentation condition for the Bacillus thuringiensis.The results showed that the final composition of the optimized fermentation conditions were as follows: initial pH 7.36,temperature 30 ℃,inoculation amount 7.5%(V/V),fermentation time 66.71 h,in the Bacillus thuringiensis liquid fermentation medium supplied with ammounium sulfate 3.08 g/L,potassium dihydrogen phosphate 1.0 g/L,magnesium sulfate 0.25 g/L,calcium chloride 0.15 g/L,and manganese sulfate 0.5 g/L.Under this condition,the biomass of Bacillus thuringiensis could reach 8.75 g/L and was 1.2 times of that using the foundation fermentation medium.