Asgard archaea, believed to be the ancestor of eukaryotes, constitute a new superphylum prevalent in diverse sediment environments. Their distribution and metabolic potentials are diversified and elusive. In the present study, the distribution and genomic characteristics of Asgard archaea in the Haima cold seep of the South China Sea (SCS) were investigated. In total, we obtained 48 high-quality metagenome-assembled genomes (MAGs), which fell into 7 separated lineages affiliated with the phyla Lokiarchaeota, Thorarchaeota, Heimdallarchaeota and Gerdarchaeota. These Asgard archaea were mainly distributed in the cold seep but rarely detected in the control marine sediments. We found that Asgard might encode complex CRISPR-Cas systems, which likely protected the archaea against abundant viruses in cold seep sediments. Phylogenomic tree indicated the novelty of cold-seep Asgard archaea, and highlighted that MAG HM7_B34 was affiliated with the newly proposed Gerdarchaeota phylum. Metabolic reconstruction indicated that Gerdarchaeota in the Haima cold seep were obligate anaerobic archaea and might undergo autotrophic lifestyle using the Wood-Ljungdahl pathway. Moreover, Gerdarchaeota might metabolize formaldehyde and likely had the ability to hydrolyze oligosaccharides including chitin. Altogether, our study expands the cognition of Asgard archaea in terms of spatial distribution, biodiversity and carbon cycle in cold seep ecosystems.

阿斯加德古细菌被认为是真核生物的祖先，构成了一种在不同沉积环境中普遍存在的新的超级植物。它们的分布和代谢潜力是多种多样且难以捉摸的。在本研究中，调查了南海海马冷渗流中Asgard古细菌的分布和基因组特征。总共，我们获得了48个高质量的由基因组组装的高质量基因组（MAG），它们分为7个独立的谱系，分别由Lokiarchaeota，Thorarchaeota，Heimdallarchaeota和Gerdarchaeota组成。这些Asgard古细菌主要分布在冷渗流中，但很少在对照海洋沉积物中发现。我们发现Asgard可能编码复杂的CRISPR-Cas系统，这可能保护古细菌免受冷渗流沉积物中大量病毒的侵害。生理系统树表明了冷深的Asgard古细菌的新颖性，并强调了MAG HM7_B34与新提出的Gerdarchaeota phylum有关。代谢重建表明，海马冷渗流中的Gerdarchaeota是专性厌氧古细菌，并可能通过Wood-Ljungdahl途径经历自养型生活方式。此外，Gerdarchaeota可能会代谢甲醛，并可能具有水解包括几丁质在内的寡糖的能力。总之，我们的研究扩展了冷泉生态系统在空间分布，生物多样性和碳循环方面对阿斯加德古细菌的认识。代谢重建表明，海马冷渗流中的Gerdarchaeota是专性厌氧古细菌，并可能通过Wood-Ljungdahl途径经历自养型生活方式。此外，Gerdarchaeota可能会代谢甲醛，并可能具有水解包括几丁质在内的寡糖的能力。总之，我们的研究扩展了冷泉生态系统在空间分布，生物多样性和碳循环方面对阿斯加德古细菌的认识。代谢重建表明，海马冷渗流中的Gerdarchaeota是专性厌氧古细菌，并可能通过Wood-Ljungdahl途径经历自养型生活方式。此外，Gerdarchaeota可能会代谢甲醛，并可能具有水解包括几丁质在内的寡糖的能力。总之，我们的研究扩展了冷泉生态系统在空间分布，生物多样性和碳循环方面对阿斯加德古细菌的认识。