Department of Biological Sciences, Missouri University of Science and Technology, Rolla, Missouri 65409-1120, USA.
Astrobiology. 2009 Dec;9(10):919-30. doi: 10.1089/ast.2008.0293.
Unique, shallow interdune lakes and groundwaters with extremely low pH and high salinity exist in Australia, along with nearby lakes that possess higher pH values. These acidic hypersaline environments are possibly the best modern terrestrial analogues for past martian environments. However, no previous microbiological analyses of these lakes have been conducted. During the Australian winter of 2005, water samples were taken from several hypersaline lakes located in southern Western Australia that possessed acidic to slightly alkaline pH. These samples were subjected to molecular analysis to identify bacterial communities. DNA extraction and polymerase chain reaction (PCR) amplification of the 16S rRNA gene sequences, by using universal bacterial primers, were also performed on the samples. Extracted DNA was amplified with 1070 forward and 1392 GC-clamped reverse primers and analyzed by using denaturant gradient gel electrophoresis (DGGE). In addition, libraries were developed from DNA retrieved from four lakes, including a marginal marine neutral lake, an inland neutral lake, and two inland acid lakes, and selected clones with distinct operational taxonomic units were sequenced. The DGGE profiles and clone sequence data indicate that there are distinct, abundant, and diverse microbial populations in these Australian hypersaline environments, especially the acidic ones. These results are significant for two reasons: (1) they provide the first microbiological survey of natural acid saline lakes and (2) they hint at the possibility that there could have been a diverse microbial population in acidic hypersaline environments on Mars.
澳大利亚存在独特的浅层沙丘间湖和地下水，其具有极低的 pH 值和极高的盐度，同时还存在 pH 值较高的附近湖泊。这些酸性高盐环境可能是火星过去环境的最佳现代陆地类似物。然而，之前并没有对这些湖泊进行微生物分析。在 2005 年澳大利亚冬季，从位于西澳大利亚州南部的几个具有酸性到弱碱性 pH 值的高盐湖泊中采集了水样。对这些样品进行了分子分析，以确定细菌群落。还对样品进行了 DNA 提取和聚合酶链反应 (PCR) 扩增 16S rRNA 基因序列，使用通用细菌引物。提取的 DNA 用 1070 正向和 1392 GC 夹反向引物扩增，并通过变性梯度凝胶电泳 (DGGE) 进行分析。此外，从包括一个边缘海洋中性湖、一个内陆中性湖和两个内陆酸性湖在内的四个湖泊中回收的 DNA 构建了文库，并对具有独特操作分类单位的选定克隆进行了测序。DGGE 图谱和克隆序列数据表明，这些澳大利亚高盐环境中存在独特、丰富和多样的微生物种群，尤其是酸性环境。这些结果有两个重要意义：（1）它们首次对天然酸性咸水湖进行了微生物调查；（2）它们暗示火星上酸性高盐环境中可能存在多样化的微生物种群。
