【摘要】 从石油污染土壤中分离到1株能以3-苯氧基苯甲酸(3-PBA)为唯一碳源生长的细菌,命名为BA3.根据其生理生化特征和16S rDNA序列相似性分析,将该菌鉴定为鞘脂菌属(Sphingobium sp.).该菌株在60 h内对100 mg.L-1的3-苯氧基苯甲酸的降解率达到99%.降解3-苯氧基苯甲酸的最适温度为30℃,pH值为7.0,降解速率与初始接种量呈正相关.拟除虫菊酯类杀虫剂水解酶基因pytH为本实验室克隆到的一个新的菊酯水解酶基因,通过PCR从菊酯降解菌株JZ-2总DNA扩增了pytH,将pytH定向克隆到pBBRMCS-5载体上,构建重组质粒pPYTH,在辅助质粒pRK600的帮助下,通过三亲接合将pPYTH转移到3-PBA降解菌株Sphingobium sp.BA3中,获得工程菌Sphingobium sp.BA3-pytH;甲氰菊酯的降解实验表明,菌株JZ-2在48 h内对50 mg.L-1的甲氰菊酯降解率仅为60%左右,工程菌BA3-pytH相同条件下对50 mg.L-1的甲氰菊酯降解率达到95%以上,同时对甲氰菊酯的降解中间产物3-PBA也能较快降解,不会对菊酯的降解产生反馈抑制.工程菌BA3-pytH因其对甲氰菊酯和其降解中间产物3-PBA的快速降解能力,比原始菌株JZ-2在菊酯污染土壤生物修复应用中更具有优势.更多还原

【Abstract】 A bacterium capable of utilizing 3-phenoxybenzoic acid(3-PBA) as sole carbon source was isolated from petroleum-contaminated soil.This bacterium,designated as BA3,was identified as Sphingobium sp.according to its physiological & biochemical characteristic and the similarity analysis of its 16S rDNA sequence.Strain BA3 was able to degrade 99% of 100 mg.L-1 3-phenoxybenzoic acid within 60 h.The optimal pH and temperature for the degradation were 7.0 and 30℃,respectively.The degradation efficiency was related positively to initial inoculum size.The pyrethroid hydrolase gene(pytH) gene was amplified from the genomic DNA of Sphingobium sp.JZ-2 by PCR.Recombinant plasmids pPYTH was constructed by ligating pytH gene into the broad host vector pBBRMCS-5.Under the help of plasmid RK600,pPYTH was transferred into Sphingobium sp.BA3 to construct engineering strain BA3-pytH;Fenpropathrin degradation experiments showed that strain JZ-2 was able to degrade only 60% of 50 mg.L-1 fenpropathrin in 48h while engineering strain BA3-pytH was able to degrade over 95% of 50 mg.L-1 fenpropathrin under the same conditions.Even more,BA3-pytH could rapidly degrade 3-PBA,metabolic products of pyrethroid insecticides,eliminating the inhibition of 3-PBA to pyrethroid hydrolase.Therefore,in contrast to strain JZ-2,engineering strain BA3-pytH had more advantages in bioremediation of pyrethroid insecticides contaminated environment.更多还原