Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babeş-Bolyai University, 5-7 Clinicilor Street, 400006, Cluj-Napoca, Romania.
Extremophiles. 2014 Mar;18(2):399-413. doi: 10.1007/s00792-013-0625-6. Epub 2014 Jan 11.
Saline, meromictic lakes with significant depth are usually formed as a result of salt mining activity. Ocnei Lake is one of the largest Transylvanian (Central Romania) neutral, hypersaline lake of man-made origin. We aimed to survey the seasonal dynamics of archaeal diversity in the water column of Ocnei Lake by employing microbiological methods as well as molecular techniques based on the sequence analysis of the 16S rRNA gene. We found that archaeal diversity in the water column increased with depth and salinity, with 8 OTUs being detected in the epilimnion compared to 21 found in the chemocline, and 32 OTUs in the monimolimnion. Down to 3.5 m depth, the archaeal community was markedly dominated by the presence of an unclassified archaeon sharing 93% sequence identity to Halogeometricum spp. At the chemocline, the shift in archaeal community composition was associated with an increase in salinity, the main factor affecting the vertical distribution of archaeal assemblages. It appears that the microoxic and hypersaline monimolimnion is populated by several major haloarchaeal taxa, with minor fluctuations in their relative abundances throughout all seasons. The culturable diversity was reasonably correlated to the dominant OTUs obtained by molecular methods. Our results indicate that Ocnei Lake represents a relatively stable extreme habitat, accommodating a diverse and putatively novel archaeal community, as 30% of OTUs could not be classified at the genus level.
盐水、微分层且深度较大的湖泊通常是由于盐矿开采活动而形成的。奥克内伊湖是特兰西瓦尼亚（罗马尼亚中部）最大的人为起源的中性、高盐湖泊之一。我们旨在通过微生物学方法以及基于 16S rRNA 基因序列分析的分子技术，调查奥克内伊湖水柱中古菌多样性的季节性动态。我们发现，水柱中古菌多样性随深度和盐度的增加而增加，与在真光层中检测到的 8 个 OTUs 相比，在化变层中发现了 21 个，在均变层中发现了 32 个 OTUs。在 3.5 米深以下，古菌群落主要由未分类的古菌组成，与 Halogeometricum spp. 的序列相似度为 93%。在化变层，古菌群落组成的变化与盐度的增加有关，盐度是影响古菌组合垂直分布的主要因素。似乎微氧和高盐的均变层由几个主要的盐古菌类群组成，它们的相对丰度在整个季节都有较小的波动。可培养的多样性与通过分子方法获得的优势 OTUs 具有合理的相关性。我们的结果表明，奥克内伊湖代表了一个相对稳定的极端生境，容纳了多样的、可能是新的古菌群落，因为 30%的 OTUs 在属水平上无法分类。
