一株芘好氧降解菌的筛选鉴定及共代谢特性研究

Isolation,Identification,and Cometabolic Performance of A Pyrene-Degrading Aerobic Strain Pseudomonas sp.M4

从胜利油田沾三区块石油污染土壤中筛选到一株能以芘为唯一碳源和能源的降解菌;通过GC-MS和HPLC-MS分析了该菌株降解芘过程中的中间代谢产物,推测了该菌株对芘的降解途径;通过测定降解酶活性,探讨了不同共代谢基质对该菌株共代谢性能的影响。结果表明,经16S rDNA序列同源性分析,所筛菌株为施氏假单胞菌,命名为Pseudomonas sp.M4。结合中间代谢产物分析,推断菌株M4同时存在两条代谢途径,即水杨酸途径和邻苯二甲酸途径。共代谢实验结果表明,相较于饱和烃和芳烃,以原油为共代谢基质可增强菌株M4对芘的共代谢作用,7 d、30 d的芘(100 mg·L^(-1))降解率分别为26.56%、61.23%。降解酶活性分析表明,添加原油可显著提高水杨酸途径中水杨酸羟化酶、邻苯二酚-2,3-双加氧酶的活性,即通过提高水杨酸途径中降解酶的活性强化菌株M4对芘的共代谢作用。

We isolated a degrading bacterium that can utilize pyrene as its sole carbon source and energy from petroleum-contaminated soil in the Shengli Oilfield(in Shandong province of China).Moreover,we analyzed the intermediate metabolites in pyrene degradation by GC-MS and HPLC-MS,and hypothesized a speculative degradation pathway.Furthermore,we discussed the effect of different cometabolic substrates on cometabolic capacity of the screened strain by measuring the activities of its degrading enzymes.The results show that,according to 16S rDNA sequence homology analysis,the screened strain belongs to Pseudomonas stutzeri,and is named as Pseudomonas sp.M4.Intermediate metabolite analyses reveal that there are two metabolic pathways(salicylic acid and phthalic acid pathways)in pyrene degradation.Cometabolism experiments show that,the cometabolic capacity of the strain M4 against pyrene is enhanced when using crude oil as a cometabolic substrate compared with saturated and aromatic hydrocarbons,and the degradation rate of pyrene(100 mg·L^(-1))cultured for 7 d and 30 d are 26.56%and 61.23%,respectively.Degrading enzyme activity analyses show that,the addition of crude oil remarkably increases the activities of salicylic acid hydroxylase and catechol-2,3-dioxygenase in the salicylic acid pathway.Thus,the cometabolic capacity of the strain M4 against pyrene is enhanced by improving the activity of degrading enzyme in the salicylic acid pathway.