复合菌株降解拟除虫菊酯农药的研究

Studies on two mixed strains for pyrethroids degradation

【目的】制备拟除虫菊酯农药高效复合降解菌株,为菊酯农药残留危害处理提供候选生物制剂。【方法】将菊酯农药降解菌株HU和ZH,按一定比例富集培养制成复合菌株,采用响应曲面法(RSM)优化其降解条件,高效液相色谱法(HPLC)测定其降解能力,并采用一级动力学模型分析其降解过程。【结果】复合菌株降解拟除虫菌酯农药的最优条件为28.5℃,pH 7.7,接种量为0.4 g/L,最佳接种比例为1∶1。在此条件下培养3 d,复合菌株对50 mg/L氰戊菊酯、溴氰菊酯、氯氰菊酯的降解率分别达到97.5%,94.3%,96.6%,较单一菌株HU(73.9%,82.3%,78.7%)和ZH的降解率(40.6%,78.4%,82.5%)分别增加了23.6%,12.0%,17.9%和56.9%,15.9%,14.1%,且降解过程符合一级动力学模型;降解半衰期(T1/2)分别为20.7,22.2和21.6 h,较单一菌株HU(34.8,29.4,32.2 h)和ZH的降解半衰期(93.6,34.3,37.1 h)分别缩短了14.1,7.2,10.6和72.9,12.1,15.5 h,复合菌株对3种菊酯农药的降解存在协同增效作用。【结论】复合菌株能有效提高3种菊酯农药残留的去除率,且HU与ZH的接种比例为1∶1时降解效果最好。

【Objective】 The study aimed to prepare efficient mixed strains for pyrethroids degradation,and provide prospect candidate biological agents for use in pyrethroid-contaminated environment.【Method】 The mixed strains were composed upon strain HU and ZH.The degradation conditions were optimized with response surface methodology（RSM）.The degradation ability of the mixed strains was evaluated with high performance liquid chromatography（HPLC）.The degradation process was analyzed with first-order kinetics.【Result】 The optimal conditions for biodegradation were obtained as follows：temperature 28.5 ℃,pH 7.7 and inocula biomass 0.4 g/L.The optimal inoculating rate was 1∶1 based on single strain HU and ZH.Under such conditions,the mixed strains could effectively degrade fenvalerate,deltamethrin and cypermethrin.The degradation rates were 97.5%,94.3% and 96.6%,respectively,increasing by 23.6%,12.0%,17.9% or 56.9%,15.9%,14.1%,compared with the single strain HU or ZH after 3 days of incubation.Furthermore,the degradation processes followed first-order kinetics and half lives（T1/2） were 20.7,22.2 and 21.6 h,respectively,which were shortened by 14.1,7.2,10.6 h or 72.9,12.1,15.5 h,compared with the single strain HU or ZH.It＇s proposed that there is a synergistic effect between strain HU and ZH on fenvalerate,deltamethrin and cypermethrin degradation.【Conclusion】 The mixed strains could greatly improve the degradation efficiency of fenvalerate,deltamethrin and cypermethrin.Obtained results showed the optimal inoculating rate of the mixed strains was 1∶1.