Below their ice shells, icy moons may offer a source of chemical energy that could support microbial life in the absence of light. In the Arctic, past and present glacial retreat leads to isostatic uplift of sediments through which cold and methane-saturated groundwater travels. This fluid reaches the surface and freezes as hill-shaped icings during winter, producing dark ice-water interfaces above water ponds containing chemical energy sources. In one such system characterized by elevated methane concentrations - the Lagoon Pingo in Adventdalen, Svalbard, Norway (~10 mg/L CH4, <0.3 mg/L O2, -0.25°C, pH 7.9), we studied amplicons of the bacterial and archaeal (microbial) 16S rRNA gene and transcripts in the water pond and overlaying ice. We found that active chemolithoautotrophic sulfur-oxidizing microorganisms (Sulfurimonas, Thiomicrorhabdus) dominate a niche at the bottom of the ice that is in contact with the anoxic water reservoir. There, the growing ice offers surfaces that interface with water and hosts favorable physico-chemical conditions for sulfide oxidation. The detection of anaerobic methanotrophs further suggests that throughout the winter, a steady-state dark and cold methane sink occurs under the ice in two steps: first, methane is oxidized to carbon dioxide and sulfates are concomitantly reduced to sulfides by the activity of anaerobic methanotrophs (ANME) ANME-1a and sulfate-reducing bacteria (SRB) SEEP-SRB1 consortia; and second, energy from sulfides is used by sulfur-oxidizing microorganisms to fix carbon dioxide into organic carbon. Our results underscore that ice-covered and dark ecosystems are hitherto overlooked oases of microbial life and emphasize the need to study microbial communities in icy habitats.

中文翻译：

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化学自养细菌在新兴的北极冷泉的深色水冰界面上繁衍生息。


在冰壳下方，冰冷的卫星可能提供一种化学能来源，可以在没有光线的情况下支持微生物生命。在北极，过去和现在的冰川消退导致沉积物等静压隆升，寒冷和甲烷饱和的地下水通过这些沉积物。这种液体到达地表，在冬季结冰为山状结冰，在含有化学能源的水池上方产生深色的冰水界面。在这样一个以甲烷浓度升高为特征的系统 - 挪威斯瓦尔巴群岛 Adventdalen 的 Lagoon Pingo （~10 mg/L CH4， <0.3 mg/L O2， -0.25°C， pH 7.9），我们研究了细菌和古细菌（微生物）16S rRNA 基因的扩增子以及水池和覆盖冰中的转录本。我们发现，活性化学自养硫氧化微生物（Sulfurimonas、Thiomicrorhabdus）在与缺氧水库接触的冰底部占据主导地位。在那里，不断增长的冰提供了与水接触的表面，并为硫化物氧化提供了有利的物理化学条件。厌氧嗜甲烷菌的检测进一步表明，在整个冬季，冰下会分两步发生稳态的黑暗和寒冷的甲烷沉降：首先，甲烷被厌氧嗜酸菌 （ANME） ANME-1a 和硫酸盐还原菌 （SRB） SEEP-SRB1 财团的活性氧化成二氧化碳，硫酸盐同时被还原成硫化物;其次，硫氧化微生物利用硫化物的能量将二氧化碳固定成有机碳。我们的研究结果强调，冰雪覆盖和黑暗的生态系统是迄今为止被忽视的微生物生命绿洲，并强调了研究冰冷栖息地中微生物群落的必要性。