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Metagenomic analysis and metabolite profiling of deep–sea sediments from the Gulf of Mexico following the Deepwater Horizon oil spill

Baruch Marine Field Laboratory, Belle W. Baruch Institute for Marine and Coastal Sciences, University of South Carolina Georgetown, SC, USA.
Frontiers in Microbiology (Impact Factor: 3.99). 03/2013; 4:50. DOI: 10.3389/fmicb.2013.00050
Source: PubMed

ABSTRACT

Marine subsurface environments such as deep-sea sediments, house abundant and diverse microbial communities that are believed to influence large-scale geochemical processes. These processes include the biotransformation and mineralization of numerous petroleum constituents. Thus, microbial communities in the Gulf of Mexico are thought to be responsible for the intrinsic bioremediation of crude oil released by the Deepwater Horizon (DWH) oil spill. While hydrocarbon contamination is known to enrich for aerobic, oil-degrading bacteria in deep-seawater habitats, relatively little is known about the response of communities in deep-sea sediments, where low oxygen levels may hinder such a response. Here, we examined the hypothesis that increased hydrocarbon exposure results in an altered sediment microbial community structure that reflects the prospects for oil biodegradation under the prevailing conditions. We explore this hypothesis using metagenomic analysis and metabolite profiling of deep-sea sediment samples following the DWH oil spill. The presence of aerobic microbial communities and associated functional genes was consistent among all samples, whereas, a greater number of Deltaproteobacteria and anaerobic functional genes were found in sediments closest to the DWH blowout site. Metabolite profiling also revealed a greater number of putative metabolites in sediments surrounding the blowout zone relative to a background site located 127 km away. The mass spectral analysis of the putative metabolites revealed that alkylsuccinates remained below detection levels, but a homologous series of benzylsuccinates (with carbon chain lengths from 5 to 10) could be detected. Our findings suggest that increased exposure to hydrocarbons enriches for Deltaproteobacteria, which are known to be capable of anaerobic hydrocarbon metabolism. We also provide evidence for an active microbial community metabolizing aromatic hydrocarbons in deep-sea sediments of the Gulf of Mexico.

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    • "It is a recurrent observation that most 16S rRNA gene sequences of uncultured organisms retrieved from oil polluted sediments are closely related to organisms detected in similar polluted sites, which suggests a common trend in the structuring of communities in the presence of oil. The enrichment of members of the Deltaproteobacteria is consistent with sulphate reduction being the prevailing respiratory metabolism in marine sediments which agrees with the observation that the abundance of sulphate-reducing Deltaproteobacteria also increased in deep-sea sediments near the DWH Macondo wellhead[39](reviewed in[21 ]). Deltaproteobacteria also constituted the prevailing group in the anoxic layer of subtidal sediments affected by the Prestige spill, dominated by the Desulfobacteraceae[33 ]. "
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    • "d washing ) , including populations with potential oil degradation capability ( Engel and Gupta , 2014 ) . Oil plumes have been shown to have an impact on microbial communities in marine sediments and other beach areas , with NGS detecting genes and transcripts indicative of pollutant ( monoaromatics and alkanes ) degradation in marine sediments ( Kimes et al . , 2013 ; Mason et al . , 2014 ) and areas along the shorelines ( Lamendella et al . , 2014 ) ."
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