Centre for Geobiology and Department of Biology, University of Bergen, Allégaten, Bergen, Norway.
ISME J. 2010 Mar;4(3):346-56. doi: 10.1038/ismej.2009.126. Epub 2009 Dec 3.
Korarchaeota constitute a recently proposed and little characterized kingdom of Archaea that might have diverged before the lineages of Crenarchaeota and Euryarchaeota split. To assess the diversity, distribution and abundance of Korarchaeota, we analysed 19 terrestrial hot springs in Hveragerdi and Krysuvik, Iceland, and in Kamchatka, Russia. The springs were 70-97 degrees C with pH 2.5-6.5. Out of 19 springs, 12 tested positive for Korarchaeota with specific primers. A Korarchaeota 16S rDNA library was made from each of these. From the 301 clones sequenced, 87 unique sequences were obtained from Iceland and 33 from Kamchatka. The similarity between Kamchatkan and Icelandic 16S rDNA sequences and that of Candidatus Korarchaeum cryptofilum was </=93.5%. Phylogenetic analyses revealed a clear separation between sequences retrieved from terrestrial and marine habitats. Within the terrestrial sequences, four clusters could be recognized showing a geographic distribution with surprisingly low diversity. Furthermore, the abundance of Korarchaeota 16S rDNA in the 12 environmental samples was analysed using quantitative PCR (qPCR), showing that Korarchaeota represent only a minor fraction of the microbial community in hot springs; however, in some cases they constitute up to 7% of all Archaea. Taxonomic profiling of an Icelandic Korarchaeota-positive habitat revealed an Aquificales-dominated community. In fact, Aquificales were dominating or present in high numbers in all 12 positive sites. Chemical analyses of three Korarchaeota-positive hot springs showed their occurrence in variable water chemistry. Our data provide new information on Korarchaeota habitats and shed light on their abundance, diversity, distribution and coexisting organisms.
古菌门构成了一个最近提出的、特征鲜为人知的古菌王国，可能在泉古菌门和广古菌门分支之前就已经分化。为了评估 Korarchaeota 的多样性、分布和丰度，我们分析了冰岛的赫维萨格迪和克赖斯维克以及俄罗斯的堪察加的 19 个陆地温泉。这些温泉的温度为 70-97°C，pH 值为 2.5-6.5。在 19 个温泉中，有 12 个用特定引物检测到了 Korarchaeota。从这些温泉中，每个温泉都制作了一个 Korarchaeota 16S rDNA 文库。从测序的 301 个克隆中，从冰岛获得了 87 个独特序列，从堪察加获得了 33 个独特序列。堪察加和冰岛的 16S rDNA 序列与 Candidatus Korarchaeum cryptofilum 的相似性</=93.5%。系统发育分析显示，从陆地和海洋生境中获得的序列之间存在明显的分离。在陆地序列中，可以识别出四个聚类，显示出具有惊人低多样性的地理分布。此外，使用定量 PCR (qPCR) 分析了 12 个环境样本中 Korarchaeota 16S rDNA 的丰度，结果表明 Korarchaeota 仅占温泉微生物群落的一小部分；然而，在某些情况下，它们构成了所有古菌的 7%。对冰岛的 Korarchaeota 阳性生境的分类学分析揭示了以 Aquificales 为主导的群落。事实上，在所有 12 个阳性位点中，Aquificales 要么占主导地位，要么数量众多。对三个 Korarchaeota 阳性温泉的化学分析表明，它们存在于可变的水化学环境中。我们的数据提供了关于 Korarchaeota 栖息地的新信息，并阐明了它们的丰度、多样性、分布和共存生物。
