Polycyclic aromatic hydrocarbon -degrading bacterium Novosphingobium sp. H25 isolated from deep sea and its degrading genes

Abstract:

[Objective] The aim of this study is to isolate novel and efficient polycyclic aromatic hydrocarbon (PAH) degarading bacteria from deep sea. [Methods] Bacteria in deep-sea water sample from Indian Ocean were enriched in the medium with crude oil as the carbon source. PAH-degrading bacteria were isolated and their degradation potential was tested by Gas Chromatography-Mass Spectrometry. PCR-primers were designed to detect the gene encoding the large subunit of aromatic-ring-hydroxylating dioxygenase. [Results] A PAHs-degrading bacterium, named H25 was obtained. Several PAHs including 2-methynaphthalene, 2, 6-dimethynaphthalene, phenanthrene and dibenzothiopheneand dibenzofuran could be used as carbon sources for growth by strain H25. Analysis of 16S rDNA sequence showed that it belonged to genus Novosphingobium with highest similarity (96%) with previously described bacteria. Two fragments of the di-oxygenase gene were obtained by PCR with size of about 700bp, which were closest to the counterpart of N. aromati-civorans DSM12444 with 99.6% and 91.0% similarities. Furthermore, two fragments named H25I (2.9 kb) and H25II(4.5kb) containing the upstream and downstream sequences were obtained by another set of primers. [Conclusion] Strain H25 was a novel PAH-degrading bacterium in deep sea environment, which might play a role in bioattenuation of PAH in oceanic environments and has potential in bioremediation of PAH contaminated environment.