Institute of Polar Sciences, National Research Council (ISP-CNR), Messina, Italy.
Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Messina, Italy.
Astrobiology. 2021 May;21(5):551-565. doi: 10.1089/ast.2020.2238. Epub 2021 Feb 1.
The genomic diversity of bacteria and archaea in brines (BC1, BC2, and BC3) from two adjacent and perennially frozen Antarctic lakes (L16 and L-2) in the Boulder Clay (BC) area was investigated together with the metabolically active fraction of both communities, by analyzing the bulk rRNA as a general marker of metabolic activity. Although similar bacterial and archaeal assemblages were observed at phylum level, differences were encountered when considering the distribution in species. Overall, the total bacterial communities were dominated by Bacteroidetes. A massive occurrence of flavobacterial sequences was observed within the metabolically active bacterial communities of the BC1 brine, whereas the active fractions in BC2 and BC3 strongly differed from the bulk communities being dominated by Betaproteobacteria (mainly members). The BC lakes also hosted sequences of the most thermally tolerant archaea, also related to well-known hyperthermophiles. Interestingly, RNA sequences of the hyperthermophilic genus were retrieved in all brine samples. Finally, a high abundance of the strictly anaerobic methanogens (such as members) within the active community suggests that anoxic conditions might occur in the lake brines. Our findings indicate perennially ice-covered Antarctic lakes as plausible terrestrial candidates for the study of the potential for extant life on different bodies of our solar system.
对来自两个相邻且常年冻结的南极湖泊（L16 和 L-2）的卤水（BC1、BC2 和 BC3）中的细菌和古菌的基因组多样性，以及两个群落的代谢活跃部分进行了研究，通过分析大量的 rRNA 作为代谢活性的一般标志物。尽管在门水平上观察到了相似的细菌和古菌组合，但在考虑物种分布时却存在差异。总体而言，总细菌群落以拟杆菌门为主。在 BC1 卤水中的代谢活跃细菌群落中，大量存在黄杆菌序列，而在 BC2 和 BC3 中的活跃部分与大量群落强烈不同，主要由β变形菌门（主要是 成员）主导。BC 湖泊还拥有最耐热古菌的序列，这些古菌也与知名的高温微生物有关。有趣的是，在所有卤水样本中都检索到了耐热属 的 RNA 序列。最后，在活跃群落中存在大量严格厌氧产甲烷菌（如 成员），这表明缺氧条件可能存在于湖卤水中。我们的研究结果表明，常年被冰覆盖的南极湖泊是研究太阳系不同天体上现存生命潜力的合理陆地候选者。
