Baruch Marine Field Laboratory, Belle W. Baruch Institute for Marine and Coastal Sciences, University of South Carolina Georgetown, SC, USA.
Front Microbiol. 2013 Mar 15;4:50. doi: 10.3389/fmicb.2013.00050. eCollection 2013.
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.
海洋底层环境（如深海沉积物）蕴藏着丰富多样的微生物群落，这些微生物群落被认为会影响大规模的地球化学过程。这些过程包括许多石油成分的生物转化和矿化。因此，人们认为墨西哥湾的微生物群落是造成深海地平线（DWH）漏油事件中释放的原油进行内在生物修复的原因。虽然已知烃类污染会使深海海水生境中的好氧、石油降解细菌富集，但对于深海沉积物中微生物群落的反应却知之甚少，因为在低氧环境中，这种反应可能会受到阻碍。在这里，我们检验了这样一个假设，即增加烃类暴露会导致沉积物微生物群落结构发生改变，从而反映在当前条件下石油生物降解的前景。我们通过对 DWH 溢油事件后深海沉积物样本的宏基因组分析和代谢物分析来验证这一假设。所有样本中都存在好氧微生物群落和相关功能基因，而在距离 DWH 井喷点最近的沉积物中，发现了更多的δ变形菌和厌氧功能基因。代谢物分析还表明，在井喷区周围的沉积物中发现了更多的假定代谢物，而在距离背景点 127 公里的沉积物中则较少。假定代谢物的质谱分析表明，烷基琥珀酸盐仍低于检测水平，但可以检测到一系列同系物的苄基琥珀酸盐（碳链长度从 5 到 10）。我们的研究结果表明，烃类暴露的增加会使δ变形菌富集，这些细菌已知能够进行厌氧烃类代谢。我们还提供了证据表明，在墨西哥湾深海沉积物中，存在一个活跃的微生物群落，能够代谢芳烃。
