LExEn: Molecular Microbial Ecology and Biogeochemistry of Methane Hydrates and Brine Pools: Distribution and Activity of Microorganisms in Two Extreme Deep Sea Environments

LExEn：甲烷水合物和盐水池的分子微生物生态学和生物地球化学：两种极端深海环境中微生物的分布和活动

• 批准号: 0085549
• 负责人: Patricia Sobecky
• 金额: $ 72.65万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-01-15 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0085549&HistoricalAwards=false
• 关键词: LExEn; Molecular; Microbial; Ecology; Biogeochemistry

The Gulf of Mexico seafloor contains vast reservoirs of liquid and gaseous hydrocarbons that overlay thick accumulations of Jurassic salt. Conduits, or focused flow regions, permit rapid vertical migration of thermogenic hydrocarbons from deep reservoirs to the sediment-water interface and, ultimately, into the water column. The close association of salt and hydrocarbon systems results in frequent co-migration of brine and hydrocarbons (oil and gas). Upon reaching the surface, the co-migration of these fluids creates distinct extreme environments capable of supporting prolific microbial communities and complex chemosynthetically-based food webs. The Gulf of Mexico setting is complicated by the mode of hydrocarbon occurrence. At one extreme, free gas and/or liquid oil is a component of a complex fluid contained in seafloor brine pools or diatremes. The fluid in these pools is hypersaline, can reach temperatures of 40 degrees C or greater, and may entrain quantities of silt or clay as ejecta or debris flows. At the opposite extreme, hydrocarbons and H2S form ice-like clathrates with water, called gas hydrates. Relatively little is known about the types of microorganisms dwelling in these environments, their genetic diversity, or their ecology and ecophysiology. This project will test the hypotheses that brines and hydrates form distinct microbial niches containing specialized communities and functions and that the dynamic interaction between the microbial activity and geochemistry of these systems results in distinctive geochemical signals that can be detected in the environment. Key functional and phylogenetic groups in the community will be identified by analysis of microbial and genetic diversity. The organisms can then be linked to their characteristic activities through measurement of biogeochemical rates (e.g. sulfide and methane oxidation, methanogenesis, sulfate reduction). Evidence of these processes is recorded in both the microbiota and the surrounding environment and can be revealed through stable isotopic analysis of cellular and environmental molecules. This information will contribute to the field of deep-sea microbiology and will lead to a better understanding of the microorganisms' adaptations to unique environments that may be present on other planetary bodies (e.g., hydrates on Europa).

墨西哥湾海底蕴藏着巨大的液态和气态碳氢化合物，覆盖着厚厚的侏罗纪盐层。导管或集中流动区使热生烃从深层储层迅速垂直迁移到沉积物-水界面，并最终进入水柱。盐和烃系统的密切关联导致了盐水和烃（油和气）的频繁共运移。在到达表面后，这些流体的共同迁移创造了独特的极端环境，能够支持多产的微生物群落和复杂的化学合成食物网。墨西哥湾的油气赋存模式使其环境复杂化。在一个极端情况下，游离气和/或液态油是海底盐池或盐膏中所含复杂流体的一种成分。这些池中的流体是高盐度的，温度可达40摄氏度或更高，并可能夹带大量的淤泥或粘土作为喷出物或泥石流。在另一个极端，碳氢化合物和H2S与水形成冰状的包合物，称为气体水合物。对于这些环境中的微生物类型、它们的遗传多样性或它们的生态学和生态生理学知之甚少。该项目将检验以下假设：盐水和水合物形成不同的微生物生态位，其中含有专门的群落和功能，微生物活动与这些系统的地球化学之间的动态相互作用产生可在环境中检测到的独特地球化学信号。将通过分析微生物和遗传多样性来确定社区中的关键功能和系统发育组。然后，可以通过测量生物地球化学速率（例如硫化物和甲烷氧化、甲烷生成、硫酸盐还原）将生物体与其特征活动联系起来。这些过程的证据记录在微生物群和周围环境中，可以通过对细胞和环境分子的稳定同位素分析来揭示。这一信息将有助于深海微生物学领域的研究，并有助于更好地了解微生物对其他行星上可能存在的独特环境的适应性（例如，木卫二上的水合物）。