Archaeal Lineages within the Human Microbiome: Absent, Rare or Elusive?
Archaeal Lineages within the Human Microbiome: Absent, Rare or Elusive?
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DOI：
10.3390/life5021333
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发表时间：
2015-05-05
期刊：
影响因子：
--
通讯作者：
Horz HP
中科院分区：
文献类型：
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作者：
Horz HP
古生菌是人类微生物群中公认的组成部分。然而，与人类各种解剖部位（如胃肠道环境、口腔和皮肤）中发现的高度多样性的细菌分类群相比，它们的代表性明显不足。由于我们对人体的“微生物”观点，包括用于描述它们的方法学概念，传统上一直倾向于细菌，问题出现了，我们目前的知识是否反映了古菌与细菌的实际比例，或者我们是否迄今未能揭示与人类相关的古菌的全部多样性。这篇综述文章假设人类体内存在不同的古细菌谱系，这仍有待我们的发现。首先，以前未被识别的分类群可能很常见，但它们躲过了传统的检测方法。最近描述的两个主要例子表明，这可能是特定古细菌谱系的情况。其次，一些古菌类群可能因为稀少或丰度低而被忽视。这方面的证据存在于广泛的系统发育谱系中，然而我们目前还不知道这些偶尔出现的生物是短暂的，还是所谓的“稀有生物圈”的重要成员，可能具有基本的生态系统功能。最后，有证据表明，不同的人群拥有不同的古菌类群，或者共享的古菌类群的丰度和活性可能不同，从而对整体微生物群产生影响。这条研究路线相当未被探索，值得进一步调查。虽然没有详尽地概括所有关于人类古菌多样性的研究，但这篇综述强调了相关的最新发现，这些发现表明，选择适当的方法方法和考虑不同的人类群体，可能会发现以前与人类无关的古菌谱系。这反过来将有助于了解不同个体的整体微生物组的变化，并最终可能导致影响人类健康的新概念/机制的出现。
Archaea are well-recognized components of the human microbiome. However, they appear to be drastically underrepresented compared to the high diversity of bacterial taxa which can be found on various human anatomic sites, such as the gastrointestinal environment, the oral cavity and the skin. As our “microbial” view of the human body, including the methodological concepts used to describe them, has been traditionally biased towards bacteria, the question arises whether our current knowledge reflects the actual ratio of archaea versus bacteria or whether we have failed so far to unravel the full diversity of human-associated archaea. This review article hypothesizes that distinct archaeal lineages within humans exist, which still await our detection. First, previously unrecognized taxa might be quite common but they have eluded conventional detection methods. Two recent prime examples are described that demonstrate that this might be the case for specific archaeal lineages. Second, some archaeal taxa might be overlooked because they are rare and/or in low abundance. Evidence for this exists for a broad range of phylogenetic lineages, however we currently do not know whether these sporadically appearing organisms are mere transients or important members of the so called “rare biosphere” with probably basic ecosystem functions. Lastly, evidence exists that different human populations harbor different archaeal taxa and/or the abundance and activity of shared archaeal taxa may differ and thus their impact on the overall microbiome. This research line is rather unexplored and warrants further investigation. While not recapitulating exhaustively all studies on archaeal diversity in humans, this review highlights pertinent recent findings that show that the choice of appropriate methodological approaches and the consideration of different human populations may lead to the detection of archaeal lineages previously not associated with humans. This in turn will help understand variations found in the overall microbiomes from different individuals and ultimately may lead to the emergence of novel concepts/mechanisms impacting human health.