两株降解菌混合对毒死蜱的降解特性研究

Biodegradation Characteristics of Chlorpyrifos by Mixed Culture of Bacillus cereus Strains

为明确2株蜡状芽孢杆菌(Bacillus cereus)混合对毒死蜱的降解效果,以混合菌对毒死蜱的降解率和菌株的生长量为依据,考察了混合菌不同配比和不同环境因素对混合菌降解毒死蜱的影响。结果表明,两菌株的比例为1∶1(V/V)时,对80 mg/L毒死蜱的降解率最高。混合菌的最适接种量为8%(V/V),添加葡萄糖有助于菌株的生长,但是不利于毒死蜱的降解,偏碱性环境对菌株的生长和毒死蜱的降解都有利。混合菌对毒死蜱的降解动力学研究发现,毒死蜱的残留浓度随着时间的延长而降低,当毒死蜱初始浓度较高时,呈现"双峰"降解曲线。两菌株混合时能够耐受20～70 g/L的NaCl浓度,且对80 mg/L毒死蜱的降解率都在41%以上。

In the present work,we investigated for the first time the degradation characteristics of chlorpyrifos by the mixed culture of Bacillus cereus strains.The optimal ratio of inoculation volume of the two strains for chlorpyrifos degradation was established.Further,the effects of the inoculation volume,glucose concentration,initial pH and the initial chlorpyrifos concentration on the degradation efficiency of chlorprifos were determined.Simultaneously,the effect of high salinity on the biodegradation activity of chlorpyrifos was also examined.The results showed that when the ratio（V/V） was 1：1,the degradation rate to 80 mg/L of chlorpyrifos reached the highest.The optimal inoculum amount of the mixed strains was 8%（V/V） of the total volume.Addition of glucose stimulated the growth of the mixed strains but did not enhance the degradation efficiency of chlorpyrifos.The alkaline environment was prone to form the biomass and to achieve a high degradation rate of chlorpyrifos by the mixed strains.When the initial concentration of chlorpyrifos was 42 mg/L,the residual concentration of chlorpyrifos decreased with the time.However,the degradation curves of chlorpyrifos at high concentrations（108,126 mg/L） followed two peaks.The degradation rate of the mixed strains to 80 mg/L of chlorpyrifos was above 41% while the sodium chloride concentration ranged from 20 g/L to 70 g/L.The results suggest that the mixed strains could be used as a potential and efficient chlorpyrifos degrader for the bioremediation of contaminated sites,especially for the cleanup of high salinity wastewater in the chlorpyrifos production enterprises.