The Diversity And Light Hydrocarbon Biodegradation Of The Oil-gas Microorganisms Enriched From The Bohai Sea Marine Sediments

The leakage enrichment of light hydrocarbon components of near-surface oil deposits may form marine oil-gas deposits. Light hydrocarbon components are prone to occur absorption and physical or chemical adsorption in this process, and biochemical effect will occur under suitable conditions. Different light hydrocarbons degrading bacteria were enriched from the marine sediment near the oil-gas field. We investigated the bacteria community structure in enrichment sediments with16S rDNA library analysis.The phylogenetic results of the C1-C5enrichment culture degrading archaea and bacteria show that the libraries biodiversity is low.Methanotorris igneus is found in the archaea homologous sequences, which indicates the presence of the symbiotic relationship between hydrocarbon degradation and methanogenic archaea.Numerous ammonia oxidizing archaea indicates that methane oxidation and ammonia oxidation are coupled to each other. Methylophilales, Methylococcales and Rhodobacterales are the dominant bacteria. Meanwhile, Acinetobacter venetianus is found. These four types of bacteria in the hydrocarbons degradation processes play a major role. The phylogenetic results of the C4-C5enrichment culture degrading bacteria show that the library biodiversity is low, and the obtained OTUs are grouped into Bacteroidetes and Proteobacteria. The Pseudomonas accounted for66%of the sequence library, Acinetobacter accounted for14%, Azoarcus accounted for8%and Flavobacterium accounted for4%. These show significant hydrocarbon biodegradation effect. The behavior of the absorption and desorption of light hydrocarbons in marine sediments was studied in laboratory by injecting light hydrocarbon mixed standard gas into the degassing marine sediments. The results of absorption show that the changes of light hydrocarbons are caused by solution and absorption primarily. The smaller the carbon numbers of light hydrocarbons molecules, the easier the solution. The bigger the carbon numbers of light hydrocarbons molecules, the easier the absorption. Meanwhile, the olefins are more prone to solution than the alkanes of the same number of carbon atoms, and the nc-alkane are more prone to absorption than the iso-alkane of the same number of carbon atoms. The results of desorption tests show that thermal desorption can play the role of desorption, and dissolved light hydrocarbons are more prone to desorption than absorbed ones. Then the light hydrocarbons degrading bacteria were inoculated into the light hydrocarbons biodegradation test device. The results show that light hydrocarbons degrading bacteria can degrade light hydrocarbons effectively. Meanwhile, the dissolution of medium and the adsorption of sediments cause the slight change of the light hydrocarbons components, which can be ignored. The biodegradation curves of light hydrocarbons show the anti-"S" shapes, but light hydrocarbons degrading bacteria generate selectivity biodegradation. The smaller the carbon numbers of light hydrocarbons molecules, the easier the biodegradation, and the n-alkane is more prone to microbial degradation than the iso-alkane of the same number of carbon atoms. The results have important guiding significance for a deeper understanding of bacterial material metabolism in geological reservoirs marine ecological environment and for the microbial prospection for oil-gas.