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AME prepress abstract   -  DOI:

Microbial diversity in marine sediments of two hydrocarbon reservoir areas in the eastern Atlantic Ocean

Xueqin Wei, Lihua Liu*, Xueping Chen, Guangrong Jin, Li Liu, Minggang Cai, Zhongyan Qiu

*Corresponding author:

ABSTRACT: Microbes are the main drivers of the biogeochemical cycles of carbon and other elements in marine sediments. The distribution of microorganisms, particularly at the centimeter-scale, demonstrates the critical role of the local biogeochemical environment. The Atlantic Ocean has enormous hydrocabon reserves, yet microbial diversity at hydrocarbon reservoir areas, a unique habitat for microorganisms, remains poorly studied. This work investigated microbial diversity of sediments from the Gulf of Guinea and the Namibia Slope, two oil and gas reservoir areas of the eastern Atlantic Ocean. Microbial diversity was paired with geochemical analyses and provided valuable information in understanding and interpreting the bacterial and archaeal community structure. Environmental factors, especially DIC and SO42- drove the microbial community structure in the eastern Atlantic Ocean. Porewater determination and the composition of the microbial community indicated that methane oxidation may occur there. Methane oxidation may be coupled with the reduction of sulfate in the continental slope of Gulf of Guinea (Site GC09), or with nitrate reduction in the Namibia Slope in northwest South Africa (Site GC02). The sediments of oil and gas reservoirs provide a suitable habitat for microbes. However, the composition of microbial communities varied at different sites. The microbial diversity and richness in the Gulf of Guinea was high, which may correspond to the high concentration of metal ions. The metabolism of Gammaproteobacteria may respond to the concentration of SO42- and DIC. Asgardarchaeota and Bathyarchaeota could play an important role in carbon reactions, and the abundance and metabolism of Lokiarchaeota may be related to the concentration of metal ions.