深渊氮循环是深海元素循环的重要环节，也是深渊生态系统起源和演化的基础。然而，深渊的氮平衡，微生物氮循环的规模与调控机制等关键科学问题尚缺乏研究。根据前期的工作，申请者提出科学假说：深渊的高压环境对细胞造成氧胁迫，刺激反硝化过程，调控微生物氮代谢，这是造成深渊氮流失的关键因素。在本申请项目中，我们将通过高压反应器技术特异性富集和分离深渊来源的氮代谢功能类群和关键物种；通过同位素标记喂养实验，在群落水平和纯培养水平检测深渊微生物的氮代谢能力，评估深渊微生物氮循环的规模；在基因组和转录组水平分析氮代谢基因、抗氧化基因、压力三者之间的关系，揭示高压刺激反硝化途径的生物学基础。这一研究将是研究深渊、深部生物圈等高压环境下微生物群体压力适应与元素循环关系的首次尝试。

The hadal nitrogen cycle is an important part of the deep sea elemental cycle and the basis for the origin and evolution of the hadal ecosystem. However, there is still a lack of research on key scientific issues such as the nitrogen balance of the trenches, the scale and regulation mechanisms of the microbial nitrogen cycle. According to the previous work, the applicant proposed the scientific hypothesis: the high pressure environment of the hadal causes oxygen stress on the cells, stimulates the denitrification process, and regulates the microbial nitrogen metabolism, which is the key factor causing the loss of nitrogen in the hadal zones. In this project, we will specifically enrich and isolate the nitrogen-metabolizing functional groups and key species through high-pressure reactor technology; detect the nitrogen metabolism capacity of hadal microorganisms at the community level and pure culture level by isotopically labeled feeding experiments, to assess the scale of hadal microbial nitrogen cycle; analyze the relationship between nitrogen metabolism genes, antioxidant genes, and high-pressure at the genome and transcriptome levels, and reveal the biological basis of high-pressure stimulation of denitrification pathway. This research will be the first attempt to study the relationship between microbial pressure adaptation and elemental cycling in high pressure environments such as hadal trenches and deep biosphere.