严格厌氧菌是人体肠道菌群中最主要的一类，它们缺乏以氧气为最终电子受体的有氧呼吸链，只能依赖无氧酵解产生能量，在厌氧环境里生存。它们不能在有氧环境中维持无氧酵解代谢，相关机制仍未得到阐明。申请者的前期研究以人体肠道厌氧菌Bacteroides thetaiotaomicron为研究模型，证实该菌在接触有氧环境后，细胞内产生了大量活性氧；活性氧在细胞内累积，氧化破坏了关键酶，导致无氧酵解途径被封堵，细菌失去能量来源而停止了生长。本项目拟借助分子微生物学、生化、酶学等手段，探索严格厌氧菌的活性氧来源及产生机理；研究厌氧菌在有氧环境里能够维持无氧代谢、产能的必要条件；鉴定氧气分子对厌氧菌的毒害性。以相关结论为基础，综合解析严格厌氧菌不能在氧化胁迫下通过无氧酵解代谢产能的分子机制。预期成果或能阐释厌氧菌与好氧菌代谢途径中主要的区别，对生物进化史添加有重要意义的补充，为肠道厌氧菌相关研究提供理论基础。

Obligate anaerobes are dominant symbionts in the human intestine. They lack the aerobic respiratory chain, which utilizes oxygen as the final electron acceptor. In anaerobic habitats, they employ a fermentation pathway to obtain energy for growth. It is still unclear why obligate anaerobes are unable to continue the fermentation in aerobic environments. Our previous research was carried out by using Bacteroides thetaiotaomicron, a major fermentative bacterium in the human gastrointestinal tract. And our results have shown as follows: the aerated anaerobic bacteria generated a high level of reactive oxygen species, key enzymes involved in the central metabolism were inactivated, the cellular central metabolism was blocked, and cells thereby stopped growing due to the lack of energy production. The present project tries to employ techniques of molecular microbiology, biochemistry, and enzymology, etc. to investigate the source of reactive oxygen species in the obligate anaerobe; to explore how the obligate anaerobe can continue its central metabolism in aerobic environments; to confirm that the molecular oxygen may toxify obligate anaerobes. Based on these research objectives, the molecular mechanism of the disabled aerobic growth for obligate anaerobes will be further elucidated. The prospective results may demonstrate the differences in the main metabolism of aerobes and anaerobes, providing new insights into biological evolution and significant supplementations for related researches.