利用城市污泥生产苏云金杆菌生物农药

用城市污水污泥和经酸水解后的城市污泥作为培养基发酵苏云金杆菌Bacillusthringiensis(B.t),与常规的黄豆粉培养基作比较.检测B.t发酵液的pH值变化,总细胞数及活孢子数以及在发酵48h后,用2龄家蚕作试虫比较3种发酵液的生物毒性.结果表明,用污泥培养的B.t总细胞数及活孢子数略低于黄豆粉培养基生产的B.t,但两者的细菌总数都在同一数量级,差别不显著.用污泥培养B.t,芽孢大量形成109个/mL的时间,比用黄豆粉培养基生产的B.t约提前10h,发酵周期明显缩短.生物毒性实验表明用污泥培养的B.t孢晶混合液比用黄豆粉生产的B.t孢晶混合液毒性高,在相同的稀释倍数下,家蚕的死亡率提高了10%,酸水解污泥毒性略差.

Production of Bacillus thringiensis using sewage sludge as raw material

Both of sewage sludge and acid pretreated (hydrolysed) sewage sludge with a solid concentration of 20g.l-! were used as an alternate culture medium to produce Bacillus thingiensis biopesticide. Soybean meal medium, a traditional culture medium in B.t production, was also used as the control in this study. Viable cell, sporulation and entomotoxicity were evaluated by colony formation unit count and silkworm bioassay with surface contamination method. It was found that different raw materials would affect greatly B.t growth and sporulation. The rate of sporulation in sludge or hydrolysed sludge treatment was much faster than that in the control, although the number of viable cells and spores were similar for three treatments at 48h with 109 /ml. Furthermore, a high entomotoxicity was observed in the sludge treatment compared to soybean meal medium. No difference between sludge and hydrolysed sludge were found concerning viable cell and sporulation. It was concluded that sewage sludge could acted as an excellent culture medium for production of Bacillus thingiensis biopesticide, which was cost-effective.