丁草胺降解菌的分离鉴定及降解特性的研究

Isolation, Identification and Characteristics of a Butachlor-degrading Bacterium

从处理农药生产废水的膜生物反应器中分离到一株能以丁草胺为惟一碳源和能源生长的细菌BD-1,经鉴定为施氏假单孢菌(Pseudomonas stutzeri)。在纯培养的条件下测定了BD-1对丁草胺的降解性能。结果表明,在接种量为菌浓度OD415=0.2,pH7.0、30℃条件下,BD-1对丁草胺的降解符合一级动力学特征,1.0、10.0和100.0mg·L-1的丁草胺的降解半衰期分别为0.11、0.60和0.96d。BD-1在不同pH及温度下对丁草胺的降解作用为pH7.0>pH6.0>pH8.0,30℃>20℃>40℃。GC/MS初步分析结果表明,丁草胺的主要微生物降解产物为2-氯-2’,6’-二乙基乙酰苯胺和2,6-二乙基苯胺。

A bacterial strain BD-1 capable of utilizing butachlor as sole carbon and energy sources was isolated from the sludge of a membrane bioreactor after successive enrichment cultures. The isolated strain BD-1 was identified as Pseudomonas stutzeri based on its morphology, physiological and biochemical characteristics, Biolog GN2 analysis together with the 16S rDNA homologue sequence analysis. The degradation characteristics of butachlor by this strain were investigated in liquid cuhure. The degradation half-lives of butachlor at concentrations of 1.0, 10.0 and 100.0 mg·L^-1 by the bacterial strain BD-1 were measured to be 0.11, 0.60 and 0.96 d, under conditions ofpH 7.0, 25℃ and biomass of OD415=0.2. The degradation rates of butachlor by BD-1 were affected by pH and temperature following an order of pH 7.0 〉 pH 6.0 〉pH8.0, and of 30℃〉20℃〉40℃, respectively. The results show that addition of the isolated strain BD-1 enhances degradation of butachlor in water. Two metabolites were extracted and identified as 2-chloro-2′,6′-diethylacetanilide, 2,6-diethylaniline and a possible pathway involved in the microbial degradation of butachlor was also proposed. Butachlor is converted to 2-chloro-2′,6′-diethylacetanilide through debutoxymethylation, and further transferred to 2,6-diethylaniline by dechloroacetylation.