| Polycyclic aromatic hydrocarbons (PAHs) are a group of compounds composed of two or more fused aromatic rings. They are persistent in the environment, and are toxic, mutagenic and carcinogenic. Aims of this study were to detect the diversity of PAHs-degrading bacteria from nearshore and deep-sea marine environments, and to characterize the predominant PAH-degraders.First, the study of a nearshore phenanthrene degrader: A PAHs-degrading strain, with phenanthrene as sole carbon and energy source, was isolated from sea water sample of Xiamen ferry dock. 16S rDNA sequences similarity analysis indicated that it was a strain of genus Novosphingobium, tentatively named Novosphingobium sp. phe-8. The degrading efficiency of phenanthrene and pyrene by phe-8 was determined by GC-MS. Phenanthrene of 100 mg/L was almost completely removed within 3 weeks, while pyrene of 10 mg/L was almost completely removed within 5 days. According to published PAHs initial dioxygenaseα-subunit gene sequences, a pair of degenerate primers were designed and a target gene fragment of about 700 bp was obtained through PCR. And sequence alignment revealed that it was similar to the bphA1f gene of Novosphingobium aromaticivorans F199, which encoded a putative naphthalene or biphenol dioxygenase. The PCR-generated partial gene fragment DNA was used as the template to prepare a digoxin-labeled probe. Southern blotting proved that the degradative genes located on a large plasmid.Second, the study of a pyrene degrader from west Pacific deep sea sediment: A PAHs degrading consortium was enriched by using pyrene as sole carbon and energy source from west Pacific benthic sediment. DGGE and sequencing analysis revealed that it was made up of many degraders, and one of the main populations was genus Cycloclasticus. It was reported that Cycloclasticus strains were obligate marine aromatic hydrocarbons degraders. A pure culture of Cycloclasticus sp. was isolated by using naphthalene vapor as sole carbon source,...
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