Marine Group I (MGI) Thaumarchaeota, which play key roles in the global biogeochemical cycling of nitrogen and carbon (ammonia oxidizers), thrive in the aphotic deep sea with massive populations. Recent studies have revealed that MGI Thaumarchaeota were present in the deepest part of oceans—the hadal zone (depth > 6000 m, consisting almost entirely of trenches), with the predominant phylotype being distinct from that in the “shallower” deep sea. However, little is known about the metabolism and distribution of these ammonia oxidizers in the hadal water. In this study, metagenomic data were obtained from 0–10,500 m deep seawater samples from the Mariana Trench. The distribution patterns of Thaumarchaeota derived from metagenomics and 16S rRNA gene sequencing were in line with that reported in previous studies: abundance of Thaumarchaeota peaked in bathypelagic zone (depth 1000–4000 m) and the predominant clade shifted in the hadal zone. Several metagenome-assembled thaumarchaeotal genomes were recovered, including a near-complete one representing the dominant hadal phylotype of MGI. Using comparative genomics, we predict that unexpected genes involved in bioenergetics, including two distinct ATP synthase genes (predicted to be coupled with H+ and Na+ respectively), and genes horizontally transferred from other extremophiles, such as those encoding putative di-myo-inositol-phosphate (DIP) synthases, might significantly contribute to the success of this hadal clade under the extreme condition. We also found that hadal MGI have the genetic potential to import a far higher range of organic compounds than their shallower water counterparts. Despite this trait, hadal MDI ammonia oxidation and carbon fixation genes are highly transcribed providing evidence they are likely autotrophic, contributing to the primary production in the aphotic deep sea. Our study reveals potentially novel adaptation mechanisms of deep-sea thaumarchaeotal clades and suggests key functions of deep-sea Thaumarchaeota in carbon and nitrogen cycling.

中文翻译：

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对最深海的Thaumarchaeota的新颖见解：它们的新陈代谢和潜在的适应机制。

第一海洋集团（MGI）Thaumarchaeota在全球氮和碳（氨氧化剂）的生物地球化学循环中起着关键作用，在人口众多的无光深海中壮成长​​。最近的研究表明，MGI Thaumarchaeota存在于海洋的最深部分—浅海带（深度> 6000 m，几乎全部由海沟组成），主要系统型与“较浅”深海区分开。但是，关于这些氨氧化剂在代谢水中的代谢和分布知之甚少。在这项研究中，宏基因组学数据是从马里亚纳海沟的0–10,500 m深海水样品中获得的。源自宏基因组学和16S rRNA基因测序的Thaumarchaeota的分布模式与先前研究报道的相符：Thaumarchaeota的丰度在深水带区（深度1000-4000 m）达到峰值，主要枝条在海区带转移。回收了几个由超基因组组装的拟潮丘脑基因组，其中包括一个接近完整的基因组，代表了MGI的优势哈德族系统型。使用比较基因组学，我们预测涉及生物能学的意外基因，包括两个不同的ATP合酶基因（预计分别与H +和Na +偶联），以及从其他极端嗜热菌水平转移的基因，例如编码假定的二-肌醇-基因。磷酸（DIP）合成酶可能在极端条件下极大地促进了哈德进化枝的成功。我们还发现，与浅水对应物相比，浅滩MGI具有遗传潜力，可以进口更多种类的有机化合物。尽管具有此特性，但旱生的MDI氨氧化和固碳基因被高度转录，提供了证据表明它们很可能是自养的，从而促进了无光深海的初级生产。我们的研究揭示了深海丘脑进化枝的潜在新颖适应机制，并提出了深海丘陵古生物在碳和氮循环中的关键功能。