Bioconversion of Sewage Sludge to Biopesticide by Bacillus thuringiensis
微生物转化污泥制备苏云金杆菌生物杀虫剂

Feasibility of bioconversion of sewage sludge to biopesticide by Bacillus thuringiensis was studied using sewage sludge as a raw material.The fermentation was also compared with conventional medium.Results showed that without any pretreatment,the nutrients contained in sewage sludge were almost sufficient for Bacillus thuringiensis growth,even with a rapid multiplicational rate.Higher viable cells and viable spores values were obtained earlier at 24 h,with 9.48×108(CFU·mL-1) and 8.51×108(CFU·mL-1) respectively,which was 12 hours earlier and nearly 20 percent higher than conventional medium.SEM of 36 h samples gave a clear phenomenon that the metabolizability in sludge was much faster with spores and crystals spreading around.The crystals in sludge seemed rather bigger and more regular.Also a better crystal protein yield of 2.80(mg·mL-1) was observed in sludge medium compared to conventional medium at the end of fermentation. Sludge fermentation for Bacillus thuringiensis reduces the producing cost,and gives better fermentation capabilities.It's expected to be a new method for sludge disposal.