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首页> 外文期刊>Astrobiology >A viable microbial community in a subglacial volcanic crater lake, Iceland
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A viable microbial community in a subglacial volcanic crater lake, Iceland

机译：冰岛冰川下火山口湖中一个可行的微生物群落

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We describe a viable microbial community in a subglacial lake within the Grimsvotn volcanic caldera, Iceland. We used a hot water drill to penetrate the 300-m ice shelf and retrieved lake water and volcanic tephra sediments. We also acquired samples of borehole water before and after penetration to the lake, overlying glacial ice and snow, and water from a nearby subaerial geothermal lake for comparative analyses. Lake water is at the freezing point and fresh (total dissolved solids = 260 mg L-1). Detectable numbers of cells were found in samples of the lake water column and tephra sediments: 2 x 10(4) ml(-1) and 4 x 10(7) g(-1), respectively. Plate counts document abundant cold-adapted cultivable organisms in the lake water, but not in the borehole (before penetration) or glacial ice. Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments amplified from genomic DNA extracted from Grimsvotn samples indicates that the lake community is distinct from the assemblages of organisms in borehole water (before penetration) and the overlying ice and snow. Sequencing of selected DGGE bands revealed that many sequences are highly similar to known psychrophilic organisms or cloned DNA from other cold environments. Significant uptake of C-14-labeled bicarbonate occurred in dark, low-temperature incubations of lake water samples, indicating the presence of autotrophs. Acetylene reduction assays under similar incubation conditions showed no significant nitrogen fixation potential by lake water samples. This may be a consequence of the inhibition of diazotrophy by nitrogen in the lake.
机译：我们描述了格里姆斯沃特火山火山口，冰岛内的一个冰下湖中的一个可行的微生物群落。我们使用热水钻穿透了300米的冰架，并回收了湖水和火山特非拉沉积物。我们还获取了渗透到湖中之前，之后，覆盖冰川冰雪的井眼水样本以及附近的地下地热湖中的水样本，以进行比较分析。湖水处于冰点并处于新鲜状态（总溶解固体= 260 mg L-1）。在湖水柱和特非拉沉积物中发现可检测到的细胞数量：分别为2 x 10（4）ml（-1）和4 x 10（7）g（-1）。盘数记录表明湖水中有大量的冷适应性生物，但在钻孔之前（渗透之前）或冰川冰中却没有。从Grimsvotn样品中提取的基因组DNA扩增的16S rRNA基因片段的变性梯度凝胶电泳（DGGE）表明，该湖泊群落与井眼水中的生物体（渗透之前）以及上覆的冰雪不同。选定的DGGE条带的测序表明，许多序列与已知的嗜冷生物或其他寒冷环境中克隆的DNA高度相似。在湖水样品的黑暗低温培养中，C-14标记的碳酸氢盐大量吸收，表明存在自养生物。在类似的培养条件下，乙炔还原试验表明湖水样品没有明显的固氮潜力。这可能是湖中氮抑制重氮营养的结果。

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