不同土壤细菌种群结构对氯嘧磺隆胁迫的响应及降解菌系的获得

应用PCR-DGGE、DNA测序等方法,在室内驯化条件下研究了8种来源于中国不同地区土壤样品细菌种群结构对氯嘧磺隆胁迫的响应。结果表明:在氯嘧磺隆100～500mg·L-1浓度梯度下,土壤细菌群落组成有明显的更迭现象,多样性发生明显变化,驯化至10周,绝大部分细菌种群消失,样品的细菌种群结构趋于简单并呈现趋同效应;DNA测序结果表明,在驯化第10周可培养Methylophilus sp.、Beta proteobacterium、uncultured bacterium成为优势菌属,所获细菌种群出现的16个优势种群中有10个与已知的具有有机污染物降解功能和有机污染环境修复功能细菌的相似性大于97%;其中5个与嗜甲基菌16S rDNA部分序列相似性达98%以上。获得了一组对氯嘧磺隆具有降解作用的细菌菌系,可在5d内将100mg·L-1氯嘧磺隆降解67%;其主要组成为嗜甲基菌属(Methylophilus sp.)、丛毛单胞菌属(Comamonas sp.)、鞘酯杆菌属(Sphingobacterium sp.)和嗜氢菌属(Hydrogenophi-lus sp.)。

Responses of bacterial community structure in different soils to chlorimuron-ethyl and acquisition of chlorimuron-ethyl degrading bacterial population

By using whole genomic 16S rDNA PCR-DGGE and sequencing analysis,this paper studied the responses of bacterial community structure of eight soil samples collected from different sites in China to chlorimuron-ethyl stress under the conditions of acclimation in laboratory.There was a notable alternation in the bacterial community structure of all eight samples during 10 weeks enrichment culture with the application of chlorimuron-ethyl increased from 100 mg·L-1 to 500 mg·L-1.By the end of the enrichment culture,the Shannon indices of the bacterial community changed significantly,with most of bacterial populations disappeared.Moreover,there was a convergence in the bacterial community structure of all soil samples.The sequencing of the distinguished bands from the 10th week DGGE profile showed that after 10 weeks culture,the culturable Methylophilus sp.and Beta proteobacterium and unculturable bacteria became dominant groups.In the sixteen dominant groups,10 of them had a similarity above 97% to the known organic pollutant degrading bacteria in phylogenetic tree,and 5 of the 10 had a similarity above 98% to Methylophilus sp.A bacterial population was obtained,which could degrade 67% of 100 mg·L-1 of chlorimuron-ethyl within 5 days.The main composition of the bacterial population was Methylophilus sp.,Comamonas sp.,Sphingobacterium sp.,and Hydrogenophilus sp.