Microbial origin of excess methane in glacial ice and implications for life on Mars.
Microbial origin of excess methane in glacial ice and implications for life on Mars.
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冰川中过量甲烷的微生物起源及其对火星生命的影响。
DOI：
10.1073/pnas.0507601102
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发表时间：
2005
影响因子：
11.1
通讯作者：
P. Price
中科院分区：
文献类型：
--
作者：
H. C. Tung;N. Bramall;P. Price
被困在3,053米深的格陵兰冰盖项目2冰芯中的甲烷提供了过去11万年来千年尺度气候变化的重要记录。然而，在冰芯最低90米的几个深度，甲烷浓度比其他深度高出一个数量级。在这些深度，我们发现了产甲烷古菌，其原位代谢解释了过量的甲烷。我们用Syto-23染色细胞的直接计数测量的所有类型微生物的总浓度跟踪了我们通过其F420自发荧光鉴定的过量产甲烷菌，并为异常层提供了独立证据。我们估计的这些深度的微生物代谢率与早期发现的岩石，沉积物和冰中微生物的代谢率的Arcidius关系是一致的。这与从实验室数据推断的自发大分子损伤率大致相同，表明被囚禁在冰中的微生物消耗代谢能量主要是为了修复DNA和氨基酸的损伤，而不是为了生长。将最近在火星大气中发现的甲烷损失率与可能的产甲烷菌的生产率等同起来，我们估计可能的火星栖息地温度约为0摄氏度，如果均匀分布在10米厚的层中，浓度约为每毫升1个细胞。
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.
影响因子：
3.9
作者：
KIRBY, TW;LANCASTER, JR;FRIDOVICH, I
通讯作者：
FRIDOVICH, I