氟氯氰菊酯是农业害虫防治中使用量较大的一种拟除虫菊酯类杀虫剂,其在环境中的残留及生物毒性已经引起广泛关注。为开发氟氯氰菊酯降解菌资源,采用富集培养法,从长期受氟氯氰菊酯污染的菜地土壤中分离到1株高效降解氟氯氰菊酯的降解菌FLQ-5。经形态、生理生化特征及16S rDNA序列系统发育分析,鉴定该菌株为巨大芽胞菌Bacillus megaterium。当接菌量为15%时,该菌5 d内对100 mg/L的氟氯氰菊酯降解率为92.3%,最适降解温度为35 ℃,最佳降解pH为6-8。降解酶定域实验表明,降解酶为胞内酶。同时该菌降解底物具有广谱性, 5 d对100 mg/L甲氰菊酯、氰戊菊酯、高效氯氰菊酯和联苯菊酯的降解率分别达到90.23%、83.17%、81.63%和60.83%。研究结果表明,菌株FLQ-5可以用于农田土壤等环境中氟氯氰菊酯农药的降解,为氟氯氰菊酯的生物修复提供理论依据。图7 参34
Cyfluthrin is a pyrethroid pesticide extensively used for the control of agricultural pests, resulting in residues and toxicity in the environment. In order to explore cyfluthrin degradation bacterium resources, this research tried to isolate cyfluthrin-degrading bacteria from the long-term cyfluthrin-contaminated agricultural soil by enriched culture. The isolated strain was identified as Bacillus megaterium based on its morphological, physiological properties and 16S rDNA sequence analysis. The strain FLQ-5 grew in the medium supplemented with cyfluthrin. The degradation rate reached 92.3% in 5 days at the inoculum concentration of 15% shaking at 30 ℃. The optimal degradation temperature and pH were 35 ℃ and between 6 and 8, respectively. The results also showed the activity of cyfluthrin-degradation was in the intracellular extraction. Strain FLQ-5 could also degrade other pyrethroids pesticides. After 5 days inoculation, the degradation rate of fenpropathrin, fenvalerate, cypermethrin and bifenthrin reached 90.23%, 83.17%, 81.63% and 60.83% respectively at the pesticides concentration of 100 mg/L. FLQ-5 is shown applicable in bioremediation of soil contaminated by cyfluthrin, that provided a rationale for bioremediation of cyfluthrin.. Fig 7, Tab 34