Vertical distribution and metabolic diversity of autotrophic microbes in the deep sediment of the challenger deep

BACKGROUND: Carbon fixation in marine ecosystems is a vital process that contributes to climate regulation, with ocean sediments playing a critical role in carbon sequestration. This process is driven by chemolithoautotrophy in marine sediments, fueled by reduced compounds, such as those containing nitrogen and sulfur. However, the vertical distribution of microbial autotrophs and their energy coupling systems remain poorly understood in many sediments. In this study, we investigated a 750 cm sediment core from the Challenger Deep, the deepest point on Earth, which harbors abundant and diverse microbes under extreme conditions. RESULTS: ) based on Pearson's correlation analysis. CONCLUSION: This study reveals the vertical distribution of microbial carbon fixation potential and diversity in sediments driven by redox conditions, highlights the crucial role of hydrogen as an energy source, and provides new insights for optimizing global deep-sea carbon cycle models. Collectively, these findings extend the redox tower theory by revealing a hadal-sediment specific distribution of autotrophic genes, characterized by persistent enrichment of energetically efficient pathways and dominant hydrogen-based energy coupling across deep sediment layers.