深海细菌TMAO还原过程与响应压力调控的机理研究

氧化三甲胺（TMAO）是深海生物主要的渗透压保护剂和微生物的物质和能量来源，在海洋氮循环中具有重要作用。多种海洋细菌可在TMAO还原酶的作用下将其还原为TMA，同时产生能量。我们近期发现，一些深海细菌中编码的多个TMAO还原酶分别受压力和底物诱导，突破了现有的TMAO还原酶仅受底物诱导的认识。我们推测，具有压力诱导型TMAO还原酶的细菌可以更迅速地响应和利用深海环境中的TMAO，更适于在物质贫瘠的深海中生存。这种独特的代谢调控方式是否属于深海细菌的普遍特征？压力如何调控TMAO还原酶表达？为了回答上述问题，本项目一方面通过高压培养和酶活分析，调查具有这种代谢特征的深海细菌的种属特征及分布规律；一方面综合使用高压模拟生化分析和拉曼光谱等方法，深入研究模式菌株中压力调控的分子机制。本研究对于揭示深海细菌介导的TMAO还原作用的生态学意义具有重要启示，也将对阐明深海氮循环机制起推动作用。

As the major osmolyte in deep-sea animals and important nutrient and energy source for microorganisms, trimethylamine N-oxide (TMAO) plays important ecological roles in the carbon and nitrogen cycle in deep-sea habitat. In bacterial metabolism, the reduction of TMAO into TMA is conducted by the TMAO reductase. Recently, we observed that several deep-sea bacteria encode multiple TMAO reductases, and they are differently regulated by substrate or high hydrostatic pressure. This discovery expanded the current knowledge that TMAO reductase is induced by substrate only. It is speculated that pressure inducible TMAO reductase enables the bacteria to respond to TMAO more quickly, thus facilating their growth in the infertile deep-sea environment. Whether the pressure regulated TMAO reductase is a common feature for deep-sea bacteria, and how does pressure regulate the reduction of TMAO remain unknown. This project will focus on the TMAO reduction regulated by pressure. By performing cultivation and enzymatic analysis under high pressures, we will study how widely the pressure regulated TMAO reduction in deep-sea bacteria is occurred. Meanwhile, the molecular mechanism of pressure regulation will be analyzed in model strain, with traditional molecular microbiology techniques in combination with Raman spectrometry and novel high pressure stimulation biochemical analysis. The results obtained will promote the understanding the ecological significance of pressure regulation on TMAO reduction in the deep-sea environment, and will shed light on the exploration of the nitrogen cycle in the deep sea habitat.