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

Abstract:

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.