厦门近海海水中多环芳烃降解菌的原位富集与降解菌多样性

摘要：【目的】为了分析厦门近海原位海水中多环芳烃降解菌的多样性。【方法】将涂有菲的聚氯乙烯（PVC）板悬挂在厦门国际邮轮码头的海水中，进行菲降解菌的原位富集。利用变性梯度凝胶电泳（Denaturing gradient gel electrophoresis，DGGE）和16S rRNA基因文库两种方法分析了在PVC板表面富集微生物的菌群结构。之后，在实验室模拟原位条件下，对PVC板表面富集的菲降解菌群进行进一步富集、分离和初步鉴定。【结果】PVC板在海水中浸没6 d后，16S rRNA基因文库分析表明，在涂菲的PVC板表面富集的菌群中解环菌属（Cycloclasticus）对应的克隆子占文库总克隆子的50%；在未涂菲的PVC板表面吸附的菌群中红杆菌科（Rhodobacteraceae）为优势菌，其对应的克隆子占文库总克隆子的47%；而解环菌属的克隆子只占文库总克隆子的2%。DGGE的分析结果也证明解环菌是菲原位富集降解菌群中的优势菌。实验室进一步富集后，从该菌群中分离鉴定出14株细菌，其中一株新鞘氨醇杆菌B14(Novosphingobium sp.B14)具有菲降解能力。但是，解环菌未能获得纯培养。【结论】菲原位富集发现，厦门近海水体中解环菌是多环芳烃的主要降解菌。

In situ enrichment and diversity analysis of PAH-degrading bacteria in the coastal seawater of Xiamen Island

Abstract: Objective] The aim of this study is to assess the diversity of polycyclic aromatic carbon (PAH)-degrading bacteria in the coastal seawater of Xiamen Island.. Methods] The phenanthrene-degrading bacteria were enriched by suspending phenanthrene-coated Polyvinylchloride (PVC) plates in the seawater close to Xiamen International Cruise Dock. PCR-DGGE and 16S rRNA gene clone library were used to analyze the bacteria colonizing on the PVC plates. Further, PAH-degrading bacteria were re-enriched in lab after the in situ enrichment and subjected to diversity analysis and key member isolation. Results] After 6 days incubation, the genus Cycloclasticus was shown to the dominant bacterium on the phenanthrene (Phe)-coated plates, which accounted for 50% of the total clones in 16S rRNA gene clone library. However, on the control plates without Phe-coating, bacteria of Rhodobacteraceae were the dominant member, which accounted for 47% of the total clones. PCR-DGGE results revealed that the genus Cycloclasticus was the dominant member in Phe-degrading consortium growing on the Phe-coated plates in situ. After re-enrichment with Phe in laboratory, 14 strains were isolated from the consortium, in which a potential novel species of belonging to Novosphingobium was identified as a Phe degrader, named strain B-14. However, the most predominant member-Cycloclasticus can not be cultivated into pure culture. Conclusion] Genus Cycloclasticus is the most important PAH-degrading bacterium in the coast sea water of Xiamen Island. This is the first evidence to our knowledge about the in situ enrichment PAH-degrading bacterium in seawater.