The geochemical process of serpentinization releases energy and organic carbon: two of the basic requirements needed to support life. Sites of active serpentinization in the deep subsurface provide the intriguing possibility of a non-photosynthetically-supported biosphere. However, serpentinization also creates conditions, such as high pH and limited electron acceptors, which may limit microbial growth and diversity. Gaining an understanding of the identity and metabolic potential of microbes that thrive in these environments may provide insight as to whether serpentinization is sufficient to independently support life. Tablelands Ophiolite in Gros Morne National Park, Newfoundland, Canada is a continental site of serpentinization where serpentinite springs form surface pools. These pools provide easy sampling access to subsurface fluids and may allow for sampling of the subsurface microbial community. However, identification of members of the subsurface community in these pools is complicated by both surface contamination and contamination by organisms that inhabit the transition zone where hydrogen-rich subsurface fluids meet oxygen-rich surface fluids. This study was designed to distinguish among these potential sources of microorganisms by using a sampling technique that more effectively samples subsurface fluids. Community dissimilarity comparisons using environmental 16S rRNA gene sequencing indicate that the sampling design led to more direct access to subsurface fluids. These results are supported by metagenomic analyses that show metabolic pathways consistent with non-photosynthetic carbon fixation in the samples expected to represent subsurface fluids and that show hydrogen oxidation pathways in samples associated with the surface sources. These results provide a clearer picture of the diversity and metabolic potential of microbial communities potentially inhabiting subsurface, serpentinite-hosted habitats.

中文翻译：

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高原蛇纹岩宿主泉中微生物群落的多样性和代谢潜力

蛇纹石化的地球化学过程会释放能量和有机碳：维持生命所需的两个基本要求。深层地下的蛇纹石化位点为非光合作用支持的生物圈提供了有趣的可能性。然而，蛇纹石化也创造了条件，例如高 pH 值和有限的电子受体，这可能会限制微生物的生长和多样性。了解在这些环境中茁壮成长的微生物的特性和代谢潜力，可能会提供有关蛇纹石化是否足以独立维持生命的见解。加拿大纽芬兰格罗斯莫讷国家公园的高原蛇绿岩是一个大陆性的蛇纹岩化遗址，蛇纹岩泉形成了地表水池。这些水池提供了对地下流体的简单采样，并且可以允许对地下微生物群落进行采样。然而，由于表面污染和居住在富氢地下流体与富氧地表流体相遇的过渡带的生物体的污染，识别这些池中地下群落的成员变得复杂。本研究旨在通过使用更有效地对地下流体进行采样的采样技术来区分这些潜在的微生物来源。使用环境 16S rRNA 基因测序进行的群落差异比较表明，采样设计可以更直接地获取地下流体。这些结果得到宏基因组分析的支持，这些分析表明代谢途径与预期代表地下流体的样品中的非光合碳固定一致，并表明与表面来源相关的样品中的氢氧化途径。这些结果更清楚地说明了可能栖息在地下蛇纹岩栖息地的微生物群落的多样性和代谢潜力。