溴氰菊酯降解菌的分离筛选与应用潜力评价

为解决杀虫剂溴氰菊酯的残留污染问题及丰富其降解菌资源库，采用富集培养法，从长期被溴氰菊酯污染的土壤中分离筛选到1株高效降解菌株XQ08，经形态学特征、生理生化及16S rDNA鉴定其为嗜麦芽寡养单胞菌Stenotrophomonas maltophilia，并对菌株发酵条件、菌剂制备方法及应用潜力进行了初步研究。结果表明:在纯培养条件下，XQ08菌株5 d内对50 mg/L溴氰菊酯的降解率可达66.76%；在35 ℃、pH=8及以麦芽糖为碳源、氯化铵为氮源的条件下可获得理想的发酵效果，同时明确了XQ08液体菌剂的制备方法。分别在室内盆栽与田间种植的香菜上喷施高剂量 (推荐剂量10倍，有效成分6.25 g/hm2) 的25 g/L溴氰菊酯乳油，于施药后2、24和48 h施用XQ08菌剂，3、5、7和9 d后，香菜上溴氰菊酯的降解率分别超过20%、50%、60%及70%；7 d后施用菌剂处理组溴氰菊酯残留量均低于0.5 mg/kg，9 d后残留量均低于0.2 mg/kg。本研究首次报道了嗜麦芽寡养单胞菌对溴氰菊酯的降解，发现其XQ08菌剂可有效促进溴氰菊酯的降解，且其降解符合一级动力学特征。嗜麦芽寡养单胞菌XQ08菌株能有效降低或清除蔬菜上的溴氰菊酯残留，具有较好的应用潜力和开发价值。

Isolation, screening and application potential evaluation of deltamethrin-degrading microorganism

In order to solve the problem of residual contamination caused by the extensive use of deltamethrin and enrich the resource library of deltamethrin-degrading microorganisms, the effective deltamethrin-degrading XQ08 strain was isolated by enrichment culture method. The strain XQ08 was identified as Stenotrophomonas maltophilia based on the morphological, physiological and biochemical characteristics, and the 16S rDNA homologue sequence analysis. The results showed that the strain XQ08 could degrade more than 66.76% of 50 mg/L deltamethrin in pure cultures within 5 d. Moreover, the ideal fermentation effect of the strain XQ08 could be achieved under the conditions of 35 ℃, pH 8.0, maltose as a carbon source and ammonium chloride as a nitrogen source. And fermentation 24 h OD₆₀₀ could reach 2.5. The optimal preparation technology of the liquid microbial agent of the strain XQ08 was developed. Under the condition of in door pot and field experiments, the XQ08 liquid microbial agent was sprayed on Coriandrum sativum at 2, 24 and 48 h after the spray of 25 g/L deltamethrin EC at a dose of 6.25 a.i.g/hm2. The application of the liquid agent of the strain XQ08 could effectively degrade or remove deltamethrin residues on C.sativum. At 3, 5 and 7 d after the application of XQ08 microbial agent, the degradation rate of deltamethrin residues on C. sativum were more than 20%, 50%, 60% and 70%, respectively. 7 and 9 d after the application of the liquid agent of the strain XQ08, the deltamethrin residues on the leaves of C. sativum were lower than 0.5 and 0.2 mg/kg, respectively. This is the first report on the degradation of deltamethrin by S. maltophilia. The degradation pattern of deltamethrin on C. sativum was found to follow first-order kinetics. The results presented here indicate that the strain XQ08 could effectively reduce or eliminate deltamethrin residues on vegetables. The strain XQ08 has attractive application potentia and value for further development.