具氯氰菊酯降解功能的植物内生细菌分离鉴定及降解特性研究

Isolation, identification, and degradation characteristics of endophytic cypermethrin-degrading bacteria

从上海郊区某农药厂附近生长的牛筋草中分离到一株能以氯氰菊酯作为唯一碳源生长的植物内生菌,命名为A-24。该菌在48 h内对20 mg·L^-1的氯氰菊酯的降解率为91.8%,72 h内可完全降解氯氰菊酯。通过生理生化观察,结合16S rRNA基因序列分析,将该菌株鉴定为Achromobacter sp.。菌株A-24降解氯氰菊酯的最适温度和pH分别为30℃和7.0;当菌株A-24的接种量≥2%时,其对20 mg·L^-1氯氰菊酯的降解效果较好,降解率在80%以上;当氯氰菊酯浓度≤50 mg·L^-1时,菌株A-24对氯氰菊酯有较高的降解率,降解率在70%以上。通过HPLC鉴定降解产物3-苯氧基苯甲酸,推测氯氰菊酯通过酯键断裂生成二氯菊酸和3-苯氧基苯甲醛,然后3-苯氧基苯甲醛生成3-苯氧基苯甲酸。本研究结果为利用功能内生细菌调控植物代谢氯氰菊酯,进而有效规避作物污染风险提供新途径。

A cypermethrin-degrading endophytic bacteria was isolated from an insecticide factory in Shanghai, China. This isolate, designated as A-24, was identified as Achromobacter sp. based on morphological, physiological, biochemical characterization, and phylogenetic analysis of the 16 S rRNA gene sequence. The strain could degrade 91.8% of 20 mg·L^-1 cypermethrin within 48 h, and completely degrade20 mg·L^-1 cypermethrin within 72 h. Strain A-24 could also utilize cypermethrin as the sole carbon source for growth. The optimum temperature and pH for cypermethrin degradation by strain A-24 were 30 ℃ and 7.0, respectively. When the inoculation volume was more than2% and the cypermethrin concentration was less than 50 mg·L^-1, strain A-24 could rapidly degrade cypermethrin. High-performance liquid chromatography analysis indicated that the strain degraded cypermethrin via hydrolysis of the carboxylester linkage to yield 3-phenoxybenzaldehyde, which was further converted into 3-phenoxybenzoic acid under the catalysis of a dehydrogenase. This study provides a new strategy for removal of cypermethrin residues from plants by endophytic bacteria.