极端嗜盐古菌固碳贮碳及其代谢新途径研究

Halophilic archaea thrive in hypersaline environments, such as the world-wide distributed salt lakes, sea salterns, saline soils and subterranean salt formations. Our previous research shows that many halophilic archaea are capable of accumulating a large amount of poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) in the presence of excess carbon sources, and we also found that CO2 can be fixed into PHBV for storage, indicating that halophilic archaea play unique and important roles in carbon cycling in hypersaline environments. This project selects the Haloferax mediterranei, a haloarchaeon with high efficiency of PHBV synthesis, as one of the primary research objects. The function and mechanism of carbon fixation and storage by this haloarchaeon will be investigated systematically from metabolism network, specific pathways, key genes, to the regulation and adaptation mechanisms, using multifaceted experimental approaches. This project will focus on elucidation of the pathways responsible for assimilation of acetyl-CoA and propionyl-CoA, especially the coupled CO2 fixation, as well as the related PHBV accumulation and mobilization. This project is expected to provide novel insights into the physiological and ecological significance of the relevant carbon assimilation pathways in haloarchaea, and shed new lights on the mechanism of microbially driven carbon cycling in extreme environments.

极端嗜盐古菌是一类独特的极端微生物资源，广泛分布于盐湖、海水盐场和盐碱土壤等各种高盐环境。我们前期研究表明，嗜盐古菌具有将CO2固定到胞内聚合物如“聚羟基丁酸羟基戊酸共聚酯（PHBV）”中进行贮存的能力，显示嗜盐古菌在高盐环境碳循环中具有独特而重要的作用。本项目以具有高效PHBV合成能力的地中海富盐菌为主要研究对象，从基因组代谢网络、关键途径、关键基因、调控及适应机制等多个层面系统研究该类海洋嗜盐古菌的固碳和贮碳功能，重点揭示嗜盐古菌同化CO2、乙酸和丙酸等简单碳源的关键途径，解析嗜盐古菌同化乙酰/丙酰-CoA并偶联CO2固定的关键酶类及其生理生化与分子生物学特征，探讨嗜盐古菌将环境中各种碳源贮存为PHBV的生理生态学意义及对高盐环境的适应机制，为认识和利用极端环境条件下微生物驱动地球碳循环的基本机制提供前沿基础。

本项目聚焦极端嗜盐古菌固碳贮碳及其代谢途径关键问题，以具有高效合成PHBV（贮碳形式）能力的地中海富盐菌为主要研究对象，从基因组代谢网络、关键基因/途径、调控、适应机制及功能产物合成及其应用等多个方面，系统展开了嗜盐古菌固碳贮碳及PHBV降解再利用过程的研究。重点解析了嗜盐古菌对乙酰-CoA和丙酰-CoA的同化途径和关键酶,及其与PHBV代谢的偶联关系，揭示了PHBV降解和再利用的关键途径，探讨了嗜盐古菌将环境中各种碳源贮存为PHBV的生理生态学意义及对高盐环境的适应机制，并智能合成了新型PHBV等功能物质开发了其高附加值应用。本项目研究成果发表学术论文24篇（其中SCI论文22篇，通讯作者论文21篇）；申请国家发明专利6项，授权1项，超额完成项目目标。本项目所取得的研究成果，不仅为认识和利用嗜盐古菌固碳贮碳及驱动地球碳循环的基本机制提供新的知识体系，也为我们进一步发掘和利用极端微生物资源提供了理论依据。