耐盐性毒死蜱降解混合菌的构建及其降解特性

Construction of salt-tolerance mixed strains and its degradation characteristics to chlorpyrifos

为明确蜡状芽孢杆菌(Bacillus cereus)混合菌株对毒死蜱的降解效果,采用正交实验的方法构建混合菌。以混合菌对毒死蜱的降解率和菌株的生长量为依据,利用单一因素实验考察了不同因素对混合菌降解毒死蜱的影响。结果表明:构建的混合菌中三菌株的体积比为1∶1∶3。在含80 mg/L毒死蜱的反应体系中,最适接菌量为8%(V/V),最适pH为7。在实验浓度下,混合菌对毒死蜱的降解符合一级动力学方程。混合菌对盐分有较高的耐受度,当反应液中氯化钠浓度在20～100 g/L之间时,混合菌对80 mg/L毒死蜱的降解率最高达61%。

In order to clear the degradation efficiency of the mixed culture of the Bacillus cereus strains,the mixed strains was constructed by the orthogonal test.Furthermore,the effects of the inoculum size,pH value,initial chlorpyrifos concentration and the salt content on the degradation efficiency were estimated by the single factor test.The results showed that the optimal ratio（V/V） of the inoculum of the three strains was 1∶1∶3.The optimal conditions of the mixed strains for chlorpyrifos degradation were as follows： inoculum size of 8%（V/V）,initial pH of 7.0.The biodegradation process conformed to the first-order kinetic model in the tested concentrations.The degradation rate to 80 mg/L of chlorpyrifos was still high and could reach the highest up to 61% while the sodium chloride concentration of the culture medium increased from 20 g/L to 100 g/L.