Defining boundaries for the distribution of microbial communities beneath the sediment-buried, hydrothermally active seafloor
Defining boundaries for the distribution of microbial communities beneath the sediment-buried, hydrothermally active seafloor
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DOI：
10.1038/ismej.2016.119
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发表时间：
2016-10
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通讯作者：
K. Yanagawa;A. Ijiri;A. Breuker;Sanae Sakai;Youko Miyoshi;S. Kawagucci;T. Noguchi;Miho Hirai;A. Schippers;J. Ishibashi;Y. Takaki;M. Sunamura;T. Urabe;T. Nunoura;K. Takai
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文献类型：
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作者：
K. Yanagawa;A. Ijiri;A. Breuker;Sanae Sakai;Youko Miyoshi;S. Kawagucci;T. Noguchi;Miho Hirai;A. Schippers;J. Ishibashi;Y. Takaki;M. Sunamura;T. Urabe;T. Nunoura;K. Takai
活跃的热液喷口下的海底微生物被认为生活在地球上生命的上限温度附近。对冲绳海槽中段的伊贺谷北部热液气田进行了钻探取心，研究了潜孔微生物群落的系统发育组成和代谢功能产物。我们只在海底以下15.8 米以下的浅层沉积物中检测到微生物细胞、代谢活动和分子特征，钻探地点距离活跃的热液喷口(450 m)适中。在钻井现场，甲烷和硫酸盐的浓度剖面以及甲烷的δ13C和δD同位素组成表明，热液的侧向流动和微生物的厌氧甲烷氧化作用。钻井过程中的现场测量将微生物宜居带的当前底部温度限制在~45 °C。然而，在过去，根据水热蚀变粘土矿物的地球化学测温估计，深度可能有更高的温度10 6-198 °C。在最深的宜居区发现的16S rRNA基因系统型与嗜热菌的16S rRNA基因系统型有关，尽管已知的超嗜热性微生物的典型序列在整个核心中缺失。总体而言，我们的结果揭示了热液油田海底以下环境中接近宜居高温极限的边界微生物群落的分布和组成。
Subseafloor microbes beneath active hydrothermal vents are thought to live near the upper temperature limit for life on Earth. We drilled and cored the Iheya North hydrothermal field in the Mid-Okinawa Trough, and examined the phylogenetic compositions and the products of metabolic functions of sub-vent microbial communities. We detected microbial cells, metabolic activities and molecular signatures only in the shallow sediments down to 15.8 m below the seafloor at a moderately distant drilling site from the active hydrothermal vents (450 m). At the drilling site, the profiles of methane and sulfate concentrations and the δ13C and δD isotopic compositions of methane suggested the laterally flowing hydrothermal fluids and thein situmicrobial anaerobic methane oxidation.In situmeasurements during the drilling constrain the current bottom temperature of the microbially habitable zone to ~45 °C. However, in the past, higher temperatures of 106–198 °C were possible at the depth, as estimated from geochemical thermometry on hydrothermally altered clay minerals. The 16S rRNA gene phylotypes found in the deepest habitable zone are related to those of thermophiles, although sequences typical of known hyperthermophilic microbes were absent from the entire core. Overall our results shed new light on the distribution and composition of the boundary microbial community close to the high-temperature limit for habitability in the subseafloor environment of a hydrothermal field.