一株深海热液环境来源的PAHs降解菌TVG9-Ⅶ的系统发育与降解基因  

Phylogenetic and degrading genes analysis of a PAH-degrading bacterium TVG9-Ⅶ from deep-sea hydrythermal environment

作　　者：董纯明[1] 陈亮[1] 廖悦婷[1,2] 邵宗泽[1] 

机构地区：[1]国家海洋局第三海洋研究所,海洋生物遗传资源重点实验室,厦门361005 [2]厦门大学生命科学院,厦门361005

出　　处：《微生物学报》2011年第11期1548-1554,共7页Acta Microbiologica Sinica

基　　金：国家海洋局第三海洋研究所基本科研业务费项目(2010007);海洋公益性行业科研专项(201005032);中国大洋协会项目~~

摘　　要：【目的】对一株深海热液环境来源的多环芳烃(PAHs)降解菌进行系统发育分析并对其降解特性和降解机制进行研究。【方法】对16S rRNA基因进行扩增和测序,进行基于16S rRNA基因序列的系统发育分析;利用GC-MS测定其对PAHs的降解率;通过构建基因组Fosmid文库,克隆PAHs降解基因簇;并利用RT-PCR和qPCR研究关键降解酶基因在不同PAHs诱导下的表达情况。【结果】从西南太平洋劳盆地热液沉积物中分离到一株PAHs降解菌株TVG9-Ⅶ,系统发育分析结果表明,该菌株属于新鞘氨醇杆菌属(Novosphingobium),与该属的Novosphingobium indicum H25T系统发育关系最为密切,它们的16S rRNA基因序列相似性高达99.7%。该菌株在21 d内对菲、荧蒽和芘的降解率分别为95.2%,57.3%和69.6%。从Fosmid文库中筛选得到一个负责PAHs降解的上游基因簇,包含了PAHs起始降解双加氧酶大小亚基(pheA1a/b)基因和一个脱氢酶基因;RT-PCR和qPCR实验表明,双加氧酶大亚基基因pheA1a在菲的诱导下上调表达4.2倍,而在萘及高环荧蒽和芘的诱导下无上调。【结论】菌株TVG9-Ⅶ是Novosphingobium属深海热液来源的PAHs降解菌,具有良好的降解特性,特别是对高环PAHs的降解效果较好。[Objective] The aim of this study is to identify a polycyclic aromatic hydrocarbons（PAHs）-degrading bacterium isolated from deep-sea hydrothermal environment,including its taxonomy,characteristics and mechanism involved in PAH degradation [Methods] The phylogeny was studied by 16S rRNA gene clone,and the degradation rates against different PAHs were determined by GC-MS.Meanwhile,PAH-degrading gene cluster was cloned by the genomic Fosmid library construction;the function of the key degrading-gene expression was examined by RT-PCR and qPCR to observe gene expression in the response to different PAHs.[Results] A PAH-degrading strain TVG9-Ⅶ was isolated from the hydrothermal chimney sample of the Lau basin in Southwest Pacific Ocean.It showed 99.7% similarities with 16S rRNA gene of Novosphingobium indicum strain H25T.The degradation rates of this strain against phenanthrene,fluoranthene and pyrene were 95.2%,57.3% and 69.6% in 21 days,respectively.A gene cluster,containing PAHs initial dioxygenase genes pheA1a and pheA1b,was obtained from genomic fosmid library,with the insertion size of 12.522 kb.The gene pheA1a was enhanced by 4.2 folds in mRNA expression in presence of phenanthrene,but expression enhancement was not observed in other tested PAHs including naphthalene,pyrene and fluoranthene.[Conclusion] Strain TVG9-Ⅶ is isolated from deep-sea hydrothermal environment in genus Novosphingobium.It can degrade many kinds of PAHs,especially the high-weight-molecular PAHs.

关 键 词：深海热液区 新鞘氨醇杆菌 多环芳烃 降解基因簇 双加氧酶 

分 类 号：X172[环境科学与工程—环境科学]