| Nowadays, intensified marine oil pollution and the frequent occurrence of oil spill accidents lead to persistent and serious pollution on marine environments and ecosystems. Bioremediation has been used widely to administer upon marine oil pollution. Additionally, one of the most important environmental bioremediation technologies is making the use of microbial degradation. Thus, the isolation and identification of oil-degrading bacteria and study of their degradation genes (alkane hydroxylase) are very important and necessary, which has very important significance in today's removing marine oil pollution process.Analysis of oil degrading bacteria in 13 samples (one is sea water sample, the other are all sediment samples) of Beibu Gulf oil spill pollution area was studied. After enrichment and screening, 80 different strains belonging to 31 genera were isolated. They belonged to Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes, among which theα-, g-Proteobacteria and Actinobacteria consisted of the majority. Additionally, there were 17 potential novel strains. Results of systematic classification and identification of strain F44-8 showed that it represents a novel species in the genus Flavobacterium, of which the name Flavobacterium beibuense sp. nov. is proposed.Also analysis of phylogenetic evolution of 12 strains (salinisphaera) isolated from different marine area and three type strains based on 16S rRNA gene, gyrB gene and BOX-PCR clustering showed that they had consistent evolution and formed an independent branch from other genera. However, these strains were divided in genus by 16S rRNA gene, gyrB genes and BOX-PCR, which divided the 15 strains into 4, 6 and 8 small branches respectively. Phylogenetic analysis based on alkB genes from 15 strains of the genus salinisphaera showed that the genus had a great diversity of alkB genes. In addition, these strains had different physiological and biochemical characteristics and had wide range of alkane degradation (C5-C38). The degradation ability of most strains have got to more than 50%.The whole genome sequencing of strain salinisphaera sp. C84B14 with excellent degradation effect was carried out. The genome is about 3.85M, consisted of 61 Scaffolds and containing about 3872 ORFs. The content of G+C mol% is 63.35 mol%. After preliminary analysis of alkane-degradation genes, 5 potential functional genes for alkane-degradation were found. Then the experiments of induction and expression with n-alkanes were conducted using RT-PCR, and preliminary analysis suggested there were two functional genes, named Alkane 1-monooxygenase gene and FMNH2-dependent monooxygenase which have the phenomenon of regulated expression during the induction and expression with n-alkanes and the quantity is twice or three times of the control. Finally, gene cluster arrangement of the two functional genes indicated that there were a lot of alcohol dehydrogenase genes and aldehyde dehydrogenase genes ralated with alkane degradation in the upstream and downstream of the two functional genes.In sum, research on the diversity of oil-degrading microorganism of 13 samples from oil pollution area in Beibu gulf was carried out and a large number of oil-degrading bacteria were gained and a novel strain was identified; a lot of degrading gene resources were gained in preliminary studies on systematical evolution and alkane-degradation functional genes of these 12 strains of genus salinisphaera and three type strains. These results have reference value in understanding of marine oil-degrading microorganism and environmental function.
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