However, no complete alk gene clusters were identied from strain HZ in this work.It had been reported that only a small number of marine bacteria with the hydrocarbondegrading ability contained complete alkB homologs and even fewer had multiple copies. These enzymes are involved in the degradation of CC alkanes.Cytochrome P, a super family of enzymes, is a versatile biocatalyst with multiple functions, catalyzing diverse reactions such as hydroxylation, epoxidation, dehydrogenation, dealkylation, dehalogenation, etc encoding the family members of cytochrome P were upregulated after strain HZ was treated with petroleum.Several genes coding for fatty acid hydroxylases, trihydroxytoluene oxygenases, and <a href="http://www.targetmol.com/compound/Ibudilast">buy
Ibudilast</a> nitropropane dioxygenases were also upregulated. The nitropropane dioxygenase catalyzes the oxygenative denitrication of nitropropane. Additionally, several oxygenases related to organic compounds degradation were not inuenced, including, dichlorophenol monooxygenase, benzoate, dioxygenase subunit alpha, and benzoate, dioxygenase large subunit.It has been demonstrated that the, dichlorophenol monooxygenase is related to the degradation of, dichlorophenoxyacetic acid. The benzoate, dioxygenase system plays an important role in aromatic compounds degradation by catalyzing the double hydroxylation of benzoate. Collectively, the oxygenases and hydroxylases mentioned above might contribute to complete the upstream oxidation of organic compounds for degradation in strain HZ.Dehydrogenases, whose activity can be regarded as an indicator for evaluating the degradation ability of microorganisms, are essential for the degradation of organic pollutants. After strain HZ was treated with petroleum, diverse dehydrogenases in the cells were upregulated. The alcohol dehydrogenase is the second enzyme of the terminal oxidation pathway for alkane degradation.It has been demonstrated that the aldehyde dehydrogenases can utilize fatty aldehydes and aromatic aldehydes as substrates. Thus, the upregulated aldehyde dehydrogenases in strain HZ might promote the utilization of aliphatic and aromatic hydrocarbons contained in the petroleum.Taken together, the identied dehydrogenases contributed to complete the dehydrogenation reactions in strain HZ.During the degradation process of petroleum hydrocarbons, a large number of fatty acids will be produced in the bacterial cells.To efciently nish subsequent hydrocarbon degradation, enough enzymes metabolizing the fatty acids must be involved.The enrichment analysis by KEGG annotation revealed that the fatty acid metabolism pathway was activated in the petroleumtreated cells, involving upregulated genes. S that a comparatively complete set of enzymes involved in the fatty acid metabolism have been activated, including several genes related to oxidation.The coding products of these genes might promote the catabolism of fatty acids produced by petroleum degradation.At the regulation level, cytochromeoubiquinol oxidase were not inuenced by petroleum treatment.Additionally, several other enzymes related to petroleum degradation were also identied, mainly including hydrolases, dehydratases, and oxidoreductases. Terminal oxidation and subterminal oxidation are two primary aerobic pathways for the degradation of nalkanes, which can coexist in some bacteria. The terminal oxidation pathway and the genes identied above might provide the basis for the degradation of petroleum components in strain HZ.It had been revealed that the genetic systems for osmoprotectant metabolism are ubiquitous in halophilic marine bacteria.However, one bacterium simultaneously possessing both betaine and ectoine biosynthetic pathways is rare. Thus, except for possessing a high GC content, another special characteristic of strain HZ might lie in its genetic systems for betaine and ectoine metabolic pathways.