Periglacial and volcanic environments are considered terrestrial analogs of Mars with regard to astrobiological characteristics due to their specific set of extreme features. Ojos del Salado, the highest volcano on Earth (6893 m a.s.l.), is surrounded by several craters, one of which harbors the highest known altitude lake (6480 m a.s.l.), which is influenced by a rare combination of extreme environmental factors, that is, low mean temperature, permafrost, fumarolic activity, acidity, and extreme low organic matter content. To assess the genetic diversity and ecological tolerance of bacteria, samples were taken in February 2016 from the sediments covered with acidic cold (pH 4.88, 3.8°C) and warm (pH 2.08, 40.8°C) water. As a control, a nonvolcanic high-altitude lake (at 5900 m a.s.l.) was also studied by both cultivation-based and next-generation DNA sequencing methods. Isolates from the crater lake showed tolerance toward acidic pH values, unlike isolates from the nonvolcanic lake. Illumina MiSeq sequencing of the 16S rRNA gene exposed simplified, although characteristically different, bacterial communities in the warm and cold water-saturated sediments. In the fumarolic creek sediments, acidophilic iron oxidizers (Ferrithrix, Gallionella) and iron reducers (Acidiphilium) were abundant, and bacteria involved in the sulfur oxidation (Hydrogenobaculum, Thiomonas) and reduction (Desulfosporosinus) were also detected. Therefore, we propose an integrated model that addresses the potential role of bacteria in the sulfur and iron geomicrobiological cycles.

中文翻译：

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活跃的火山活动对海拔最高的Ojos del Salado火山口湖（Dry Andes，Altiplano-Atacama地区）中细菌群落的影响。

由于天体生物学特性的特殊特征，周缘和火山环境被认为是火星的陆地类似物。Ojos del Salado是地球上最高的火山（6893 m asl），周围有多个火山口，其中一个火山口是已知海拔最高的湖泊（6480 m asl），受极端环境因素的罕见影响，即，平均温度低，永久冻土，富马酸，酸度和极低的有机物含量。为了评估细菌的遗传多样性和生态耐受性，2016年2月从覆盖有酸性冷水（pH 4.88，3.8°C）和温水（pH 2.08，40.8°C）的沉积物中取样。作为对照，一个非火山高海拔湖泊（海拔5900 m ）还通过基于培养的DNA测序方法和下一代DNA测序方法进行了研究。火山口湖的分离物显示出对酸性pH值的耐受性，这与非火山湖的分离物不同。暴露于16S rRNA基因的Illumina MiSeq测序简化了，尽管在特征上不同，但在温水和冷水饱和沉积物中的细菌群落。在富马河小河沉积物中，嗜酸性铁氧化剂（Ferrithrix，Gallionella和铁还原剂（Acidiphilium）丰富，还发现了参与硫氧化（Hygengenobaculum，Thiomonas）和还原（Desulfosporosinus）的细菌。因此，我们提出了一个综合模型来解决细菌在硫和铁地球微生物循环中的潜在作用。