Thaumarchaeota constitute an abundant and ubiquitous phylum of Archaea that play critical roles in the global nitrogen and carbon cycles. Most well-characterized members of the phylum are chemolithoautotrophic ammonia-oxidizing archaea (AOA), which comprise up to 5 and 20% of the total single-celled life in soil and marine systems, respectively. Using two high-quality metagenome-assembled genomes (MAGs), here we describe a divergent marine thaumarchaeal clade that is devoid of the ammonia-oxidation machinery and the AOA-specific carbon-fixation pathway. Phylogenomic analyses placed these genomes within the uncultivated and largely understudied marine pSL12-like thaumarchaeal clade. The predominant mode of nutrient acquisition appears to be aerobic heterotrophy, evidenced by the presence of respiratory complexes and various organic carbon degradation pathways. Both genomes encoded several pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenases, as well as a form III RuBisCO. Metabolic reconstructions suggest anaplerotic CO2 assimilation mediated by RuBisCO, which may be linked to the central carbon metabolism. We conclude that these genomes represent a hitherto unrecognized evolutionary link between predominantly anaerobic basal thaumarchaeal lineages and mesophilic marine AOA, with important implications for diversification within the phylum Thaumarchaeota.

中文翻译：

---

宏基因组组装的基因组揭示了基础海洋奇古菌谱系的独特代谢适应性。

Thaumarchaeota 构成了一个丰富且无处不在的古细菌门，在全球氮和碳循环中发挥着关键作用。该门中最具特征的成员是化学自养氨氧化古菌 (AOA)，它们分别占土壤和海洋系统中单细胞生命总数的 5% 和 20%。使用两个高质量的宏基因组组装基因组 (MAG)，我们在这里描述了一个发散的海洋 thaumarchaeal 进化枝，它没有氨氧化机制和 AOA 特定的碳固定途径。系统基因组学分析将这些基因组置于未培养且大量研究不足的海洋 pSL12 样 thaumarchaeal 进化枝中。养分获取的主要模式似乎是有氧异养，呼吸复合物和各种有机碳降解途径的存在证明了这一点。两个基因组都编码了几种吡咯并喹啉醌 (PQQ) 依赖性醇脱氢酶，以及 III 型 RuBisCO。代谢重建表明由 RuBisCO 介导的回补 CO2 同化，这可能与中央碳代谢有关。我们得出的结论是，这些基因组代表了主要厌氧的基础 thaumarchaeal 谱系和嗜温海洋 AOA 之间迄今为止未被认识的进化联系，对 Thaumarchaeota 门内的多样化具有重要意义。这可能与中央碳代谢有关。我们得出的结论是，这些基因组代表了主要厌氧的基础 thaumarchaeal 谱系和嗜温海洋 AOA 之间迄今为止未被认识的进化联系，对 Thaumarchaeota 门内的多样化具有重要意义。这可能与中央碳代谢有关。我们得出的结论是，这些基因组代表了主要厌氧的基础 thaumarchaeal 谱系和嗜温海洋 AOA 之间迄今为止未被认识的进化联系，对 Thaumarchaeota 门内的多样化具有重要意义。