萘降解菌NAP_A的分离、降解性能和分子系统学研究

Study on the isolation, catabolic capability and molecular phylogeny of a naphthalene degrading bacterium NAP_A

该文研究降解多环芳烃类环境污染物的微生物资源、降解活性和分子系统特征。利用萘-无机盐选择性培养基分离萘降解菌，用培养技术和气相色谱法检测菌株对底物的利用和降解情况，用分子克隆技术获得菌株的16SrRNA基因并测序，用DNAMAN软件对菌株的16SrRNA堪因序列进行比对和系统发育分析。从淄博张店污水处理厂的活性污泥中分离到一株能降解萘的菌株NAP_A。此菌株在30—35℃和pH7条件下较快的降解底物萘，其中30℃下，10d内可以将初始质量浓度为320mg·L^-1的萘降解90％±4．5％。对菌株NAP_A的16SrRNA基因进行了克隆和测序（EU142847），基于菌株NAP_A和相关菌株的16SrRNA堪因进行系统发育分析，结果表明菌株NAP_A位于苍白杆菌属的分枝中，其中与假中间苍白杆菌种的同源性最高，可达99％，因此推断NAP_A菌是一株假中间苍白杆菌。此前并无苍白杆菌属成员降解多环芳烃的报道。这是首例苍白杆菌属成员降解多环芳烃的报道，对今后在环境污染防治中开发利用此类细菌具有指导意义。

Objective It was to study the resources, catabolic capability and molecular phylogeny of microbes degrading environmental pollutants such as polycyclic aromatic hydrocarbons. Methods a selective naphthalene-mineral medium was used to isolate naphthalene-degrading bacterium, cultivating technique and gas chromatography methods were used to determine the degrading of substrates, molecular cloning technique was used to obtain the 16S rRNA gene then it was sequenced, finally, DNAMAN software was used to multialign the relative los rRNA gene sequences and to construct the phylogenetic tree. Results A naphthalene-degrading bacterium NAP_A was isolated from the activated sludge of Zhangdian wastewater treatment plant in Zibo. The strain degraded naphthalene well under 30 ℃ -35℃ and pH7. The los rRNA gene of strain NAP A was cloned and sequenced （EU142847）. Basing on the sequence and the related sequences in the GenBank database, a multialignment was conducted then a phylogenetic tree was constructed. It showed that strain NAP A located in the lineage of Ochrobactrum genus, and it had the highest similarity with O. pseudintermedium （99%）, which indicated the strain NAP A was a member of O. pseudintermedium. Conclusion The study revealed for the fist time that Ochrobactrum member could degrade polycyclic aromatic hydrocarbon, which would guide the treatment of environmental contaminations with the bacterium.