Microbial Community Structure Characteristic In The Potential Area Of Gas Hydrate Zone In Northern South China Sea And Its Significance To Gas Hydrate

Gas hydrates are clean and green energy, are the hotspot research in twenty-first century, and biogenic is the main original in vast regions of worldwide. While the research of gas hydrate and its formation mechanism is still at a grouping stage, especially the formation mechanism at control of microbial. To understand the characteristics of microbial diversity and community structures in gas hydrate potential regions and to evaluate the relationship between bacterial community with the formation and decomposition of gas hydrate, we adapted16S rRNA-Denaturing gradient gel electrophoresis(DGGE) and Terminal restriction fragment length polymorphism(T-RFLP) technology combine such as sediments partical size, total organic carbon content, carbon and oxygen isotope environment parameters of sedimentary organic geochemistry, to illustrate the microbial community structure, as well as the affect of chemical environment to microbial community and the indicating significance for gas hydrate formation and decomposition. It was enumerated as below:(1) The main methane oxidation bacterial was Proteobacteria, and contain α-、 β-、y-Proteobacteria subgroups, and the main sulfate reduction bacterial was δ-Proteobacteria.(2)Through compare T-RFLP chromatogram to Mica3database and sequence the DGGE bands showed that: Proteobacteria were the dominant phylum in973-4core, and y-,8-proteobacteria were the main class within Proteobacteria, other bacteria include Actionmycetes, Firmicutes and Chloroflexi. The dominated community was8-Proteobacteria in20cm to382cm, α-Proteobacteria、δ-Proteobacteria was dominated in552cm to796cm, α-Proteobacteria and uncultured microbial was dominated in862cm to1196cm, the dominated microbial have a close relation with sulfate reduction and oxidation of methane, its indicated that in the areas of973-4zone, the methane metabolism and sulfur metabolism was complete by microbial, have a similarity with the zone where have confirm existing gas hydrate, suggest that this zone may be exist gas hydrate. The973-5areas was domain by α-、β-Proteobacteria; and8-Proteobacteria main exit in285cm to870cm, indicated that this zone have strong oxidation of methane, and sulfate reduction was occur mainly in 570cm to870cm. The973-3was domain by α-、β-Proteobacteria, and γ-Proteobacteria mainly exit in top to243cm, speculate that the methane mainly located below243cm, and oxidation of methane was the main reaction,δ-Proteobacteria distribution in147cm to630cm, and sulfate reduction was mainly in147cm to630cm.(3)The main archeal community in three cores were Methanosarcinales, Methanomicrobiales and Methanosaeta, but the973-3core was dominant by the Methanosaeta and it utilized the acetic to produced CH4,973-4and973-5cores were dominant by the Methanomicrobiales and it utilized the CO2and H2to produced CH4, and this result indicated that the three cores exit methane production and methane oxidation process although the substrate was different.(4)Connected the main bacterial and archeal community in three cores, and can conducted that the973-4and973-5cores exit high flux methane, and973-3core have lower flux methane.(5)Connected the variable characteristics of bacterial and archeal community with depth of the three cores and the CH4content, infer that the sulfate methane transition zone(SMTZ) was located in500cm to800cm at973-4station; and the SMTZ was located in570cm to870cm at973-5station.(6)The deposition rate was always greater than3cm/ka in the973-3,-4,-5sediment cores, was meet the sediment environment factors to the formation of gas hydrate. The sediments belongs mainly to silts, The partical size was mean, and its affect to microbial community was very low. The content of organic carbon between0.36%to1.26%, generally larger than0.5%, could offer sufficient organic matter for CO2reduction to form CH4. At the same time, the change of organic carbon will effect the microbial community structure, there are high microbial richness and diversity in the depths of organic-rich sediments. The microbial community have some similarity between surface layer and deeper layer in three cores, and in the depths of high CH4concentration the microbial community was different with other depths, it contain type II methanotroph.(7)This research connected DGGE and T-RFLP technology to learn the community structure, the result can match each other, the date is reliability.