白腐真菌对异狄氏剂的降解特性及降解机理

Degradation Characteristics and Mechanism of Endrin by a White Rot Fungus,Phlebia acanthocystis TMIC34875

异狄氏剂作为一种防治农业害虫的杀虫剂在世界范围内曾被大量使用,其在环境中的残留及生物毒性已经引起广泛关注.为开发异狄氏剂降解菌资源,并阐明异狄氏剂的微生物降解机制,采用液体培养法研究了一株对狄氏剂具有降解能力的白腐真菌Phlebia acanthocystis TMIC34875对异狄氏剂的降解性能及机理.结果表明,在菌体接种量为15%(V/V)时,异狄氏剂在10 d培养期间的降解率达到最高的57%左右.该菌株在异狄氏剂的初始浓度为20μmol L-1时具有最大降解速率,为0.053μmol L-1h-1.在培养温度为25-35℃,pH值为4.5-5.5之间时,菌株对异狄氏剂具有较好的降解效果.相同条件下,菌株在马铃薯液体培养基中显示出比在Kirk合成液体培养基中更高的降解活性.通过气相色谱–质谱分析发现了多个未曾报道过的代谢产物,包括3个单一羟基化产物和1个羧基化产物,表明该菌株对异狄氏剂的降解途径不同于已知的细菌降解途径.

Endrin is an organochlorine pesticide that was extensively used for the control of agricultural pests in the past several decades around the world. In this study, degradation characteristics and mechanism of endrin was investigated using a white rot fungus, Phlebia acanthocystis TMIC34875, which is capable of degrading dieldrin. The degradation rate was about 57% when the strain with an inoculum amount of 15% was incubated for 10 d. This strain showed the comparatively greatest degradation rate （0.053 pmol L1 h-1） with initial endrin concentration of 20 lamol L1. The optimal pH and temperature for endrin degradation were 4.5-5.5 and 25-35 ~C, respectively. The strain showed the higher degradation activity of endrin in the PDB medium than in Kirk medium. At least five metabolites of endrin including three hydroxylated products and a carboxylic acid product were detected from fungal culture using GC/MS analysis, indicating that the metabolic mechanism of endrin degradation by P. acanthocystis TMIC34875 is different from the known pathway. Fig 8, Ref21