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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Microbial origin of excess methane in glacial ice and implications for life on Mars.
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Microbial origin of excess methane in glacial ice and implications for life on Mars.

机译：冰河中过量甲烷的微生物来源及其对火星生命的影响。

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摘要

Methane trapped in the 3,053-m-deep Greenland Ice Sheet Project 2 ice core provides an important record of millennial-scale climate change over the last 110,000 yr. However, at several depths in the lowest 90 m of the ice core, the methane concentration is up to an order of magnitude higher than at other depths. At those depths we have discovered methanogenic archaea, the in situ metabolism of which accounts for the excess methane. The total concentration of all types of microbes we measured with direct counts of Syto-23-stained cells tracks the excess of methanogens that we identified by their F420 autofluorescence and provides independent evidence for anomalous layers. The metabolic rate we estimated for microbes at those depths is consistent with the Arrhenius relation for rates found earlier for microbes imprisoned in rock, sediment, and ice. It is roughly the same as the rate of spontaneous macromolecular damage inferred from laboratory data, suggesting that microbes imprisoned in ice expend metabolic energy mainly to repair damage to DNA and amino acids rather than to grow. Equating the loss rate of methane recently discovered in the Martian atmosphere to the production rate by possible methanogens, we estimate that a possible Martian habitat would be at a temperature of approximately 0 degrees C and that the concentration, if uniformly distributed in a 10-m-thick layer, would be approximately 1 cell per ml.
机译：3053米深的格陵兰冰原项目2冰芯中截留的甲烷是过去11万年来千年规模气候变化的重要记录。但是，在冰芯最低90 m处的几个深度处，甲烷浓度比其他深度处的甲烷浓度高一个数量级。在这些深度处，我们发现了产甲烷的古细菌，其原位代谢占甲烷的过量。我们通过直接计数Syto-23染色的细胞测量的所有类型微生物的总浓度追踪了我们通过F420自发荧光鉴定出的产甲烷菌的过量，并为异常层提供了独立的证据。我们估计在这些深度处的微生物的代谢率与先前发现的被囚禁在岩石，沉积物和冰中的微生物的代谢率的阿伦尼乌斯关系一致。它与从实验室数据推断出的自然大分子损害的发生率大致相同，这表明被囚禁在冰中的微生物会消耗新陈代谢的能量，主要是为了修复对DNA和氨基酸的损害而不是使其生长。与最近在火星大气中发现的甲烷的损失率与可能的产甲烷菌的生产率相提并论，我们估计可能的火星栖息地温度约为0摄氏度，如果浓度均匀分布在10-m -厚的层，大约是每毫升1个细胞。

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