蓝藻发酵生产微生物农药的影响因素研究

Factors affecting the production of Bacillus thuringiensis biopesticide using blue algae as raw material

采用摇瓶发酵试验探讨了蓝藻为原料制备苏云金杆菌生物杀虫剂的可行性,并考察了不同培养条件(蓝藻含固率、种龄、接种量、初始pH、摇床转速、发酵温度)对苏云金杆菌生长增殖、产孢与产毒效果的影响。研究结果表明,无需任何预处理工序,Btk 130菌株能在蓝藻为唯一原料的培养基中正常生长发育,并且产孢产毒。发酵48 h后,芽孢产率达到86.7%,远高于常规培养基;生物毒效为282 IU.mL-1,与常规培养基相当。培养条件优化结果表明,在蓝藻含固率为2%、初始pH为7.0、接种物种龄为9 h、接种量为2%、培养温度为30℃、摇瓶转速为200 r.min-1的条件下培养48 h,Btk 130可达到较好的发酵效果,活菌数及抗热芽孢数可达7.32 CFU.mL-1和6.38 CFU.mL-1,生物毒效为528 IU.mL-1。该研究不仅为蓝藻提供了高附加值的处置新途径,而且可显著降低生物杀虫剂的生产成本,具有广阔的应用前景。

This study investigated the bioconversion of blue algae into Bacillus thuringiensis based biopesticides.The shake-flask experiments were conducted to study the effects of solid concentration of blue algae,inoculum age,inoculation amount,initial pH,shake frequency and fermentation temperature on the bacterial growth,spore formation and toxin production by Bacillus thuringien-sis subsp.kurstaki（Btk）.The experimental results showed that the blue algae wastewater,without any pretreatment procedures,was a potential raw material for Btk growth,sporulation and endotoxins synthesis.After 48-h fermentation,a higher sporulation of 86.7% was observed using blue algae wastewater compared to the Luria-Bertani medium,and an entomotoxicity of 282 IU？mL-1 was achieved that was comparable to the value obtained from the Luria-Bertani medium.The optimal fermentation conditions for Btk production were： 2% for solid concentration of blue algae,7.0 for initial pH,9 h for inoculum age,2% for inoculum size,200 r？min-1 for shake frequency and 30 oC for fermentation temperature.The optimal condition for Btk fermentation resulted in a total viable count of 7.32 CFU？mL-1,a heat-resistant spore count of 6.38 CFU？mL-1 and an entomotoxicity value of 528 IU？mL-1 at 48 h.This new approach offers a safe environmental alternative for blue algae wastewater treatment/disposal,and also a promising way to re-duce the production cost of biopesticides.