马里亚纳海沟表层沉积物中微生物的群落组成和功能特征

深渊是迄今人类认识最少的海洋环境之一。深渊蕴含着丰富的微生物生物量,表现出活跃的有机碳周转特征,是深海有机碳降解的“热点”区域。然而,人类对深渊微生物的物种组成和代谢潜力还知之甚少。本文通过宏基因组技术与生物信息学分析,研究马里亚纳海沟“挑战者深渊”表层沉积物（水深10,853米）中的微生物群落组成和功能特征,揭示深渊表层沉积物中微生物驱动深海生物地球化学循环的潜在机制及其相应的生态效应。研究结果表明,变形菌门（Proteobacteria）、奇古菌门（Thaumarchaeota）、拟杆菌门（Bacteroidetes）、放线菌门（Actinobacteria）和浮霉菌门（Planctomycetes）是马里亚纳海沟表层沉积物中微生物的优势类群。表层沉积物中微生物的代谢分析表明其主要营异养代谢,可以降解多种有机物,包括一些难降解有机碳化合物（如邻苯二甲酸盐或其他芳香族化合物）。这些结果说明深渊沉积物中的微生物群落具有多样化的有机碳代谢能力,可以支持其开展活跃的有机碳降解过程。除了异养代谢过程,氨氧化等自养代谢过程在本研究的深渊微生物群落中也占据着重要地位,说明自养固碳可能是深渊表层沉积物中有机碳的重要来源。

Composition and metabolic potential of microbial communities in the surface sediments of the Mariana Trench

The hadal zone remains one of the least-explored marine biospheres on Earth. Accumulated evidence suggests the existence of abundant microbial communities and active microbial carbon turnover in the sediment of hadal trenches, making the hadal biosphere a "hotspot" of organic carbon degradation in the deep ocean. However, little is known about the composition and metabolic potentials of hadal microbial communities. In this study, we utilized metagenomic sequencing and in-depth bioinformatic analysis to study the composition and functional capacities of microbial communities in the surface sediments of the "Challenger Deep", the Mariana Trench (water depth 10 853 m). The ultimate goal was to reveal the potential mechanism of hadal microorganisms to drive the biogeochemical cycles in the deep ocean and the consequential ecological effects. The results showed that Proteobacteria (Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Deltaproteobacteria), Thaumarchaeota, Bacteroidetes, Actinobacteria, and Planctomycetes were the dominant taxa in the surface sediments of the Mariana Trench. Functional annotation with particular focus on the metabolism related to carbon, nitrogen, and sulfur cycles showed that the studied microbial communities in the Mariana Trench dominated by heterotrophic processes, with the capability to degrade a wide range of organic carbon (OC) compounds, including some recalcitrant OC, such as phthalate or other aromatic compounds. The findings suggest a strong capability of the analyzed microbial communities for degradation of organic carbon compound, supporting their active roles in processes of organic matter degradation. In addition to the heterotrophic metabolism, the results also showed that autotrophic metabolic processes such as ammonia oxidation may occupy an important position in the analyzed microbial community, suggesting that the microbially fixed carbon may be an important source of organic carbon in the hadal sediment of the Mariana Trench.