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首页> 外文期刊>Astrobiology >Geochemical Constraints on Sources of Metabolic Energy for Chemolithoautotrophy in Ultramafic-Hosted Deep-Sea Hydrothermal Systems
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Geochemical Constraints on Sources of Metabolic Energy for Chemolithoautotrophy in Ultramafic-Hosted Deep-Sea Hydrothermal Systems

机译：超基性基质深海热液系统中化石自养作用代谢能来源的地球化学约束。

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摘要

Numerical models are employed to investigate sources of chemical energy for autotrophic mi-crobial metabolism that develop during mixing of oxidized seawater with strongly reduced fluids discharged from ultramafic-hosted hydrothermal systems on the seafloor. Hydrothermal fluids in these systems are highly enriched in H_2 and CH4 as a result of alteration of ul-tramafic rocks (serpentinization) in the subsurface. Based on the availability of chemical energy sources, inferences are made about the likely metabolic diversity, relative abundance, and spatial distribution of microorganisms within ultramafic-hosted systems. Metabolic reactions involving H_2 and CH_4, particularly hydrogen oxidation, methanotrophy, sulfate reduction, and methanogenesis, represent the predominant sources of chemical energy during fluid mixing. Owing to chemical gradients that develop from fluid mixing, aerobic metabolisms are likely to predominate in low-temperature environments (<20-30℃), while anaerobes will dominate higher-temperature environments. Overall, aerobic metabolic reactions can supply up to ～ 7 kJ of energy per kilogram of hydrothermal fluid, while anaerobic metabolic reactions can supply about 1 kJ, which is sufficient to support a maximum of ～120 mg (dry weight) of primary biomass production by aerobic organisms and ～20-30 mg biomass by anaerobes. The results indicate that ultramafic-hosted systems are capable of supplying about twice as much chemical energy as analogous deep-sea hydrothermal systems hosted in basaltic rocks.
机译：数值模型被用来研究自养微生物代谢的化学能来源，这些物质在氧化海水与从海底超镁铁质热液系统排放的强烈还原的流体混合过程中产生。这些系统中的热液在地下富含超镁铁质岩（蛇纹岩化），从而使H_2和CH4高度富集。根据化学能源的可用性，推断出超镁铁质宿主系统中微生物可能的代谢多样性，相对丰度和空间分布。涉及H_2和CH_4的代谢反应，尤其是氢氧化，甲烷氧化，硫酸盐还原和甲烷生成，是流体混合过程中化学能的主要来源。由于流体混合产生的化学梯度，有氧代谢可能会在低温环境（<20-30℃）中占主导地位，而厌氧菌将在高温环境中占主导地位。总体而言，有氧代谢反应每千克热液可提供约7 kJ的能量，而厌氧代谢反应可提供约1 kJ的能量，足以支持最大120毫克（干重）的一次生物质生产。好氧生物和厌氧菌约20-30 mg的生物量。结果表明，超镁铁质宿主系统能够提供的化学能量是玄武岩中类似深海热液系统的两倍。

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