铁细菌与铁氧化物半导体矿物在日光下协同作用机制及其环境意义

铁细菌-铁氧化物矿物相互作用是地表环境中重要的生物地球化学过程，对水圈元素循环具有重要的影响作用。本项目拟研究模式铁还原菌Shewanella oneidensis MR-1和赤铁矿在日光下协同作用进行能量转化和电子转移的机制。从微生物产电呼吸和赤铁矿光催化作用两方面系统分析光生电子和生物电子在铁细菌-铁氧化物半导体矿物界面的传递过程。产电呼吸的影响将从蛋白质分子、基因工程改造菌、合成微生物群落三个不同层次研究细胞色素蛋白、代谢速率、胞外分泌物等因素对协同产电效率的影响；在矿物光催化方面，主要从杂质对矿物能带结构的调控和黄素对矿物光敏性的改变两方面进行研究，探讨赤铁矿半导体性质对于光催化反应-产电呼吸耦合过程的影响。基于对赤铁矿-希瓦氏菌在日光照射下协同作用机制的认识，考察该体系对水中污染物的去除效率，为认识铁细菌-半导体矿物在日光下的协同作用对水圈元素循环的影响提供理论依据。

The interaction between iron-reducing bacteria and iron oxide minerals is an important biogeochemical process, significantly influencing the geochemical cycling of elements in hydrosphere. In this project, the synergetic mechanisms of iron-reducing bacterium, Shewanella oneidensis MR-1, and semiconducting iron oxide, hematite, in electricity generation and energy conversion under sunlight irradiation will be systematically investigated. The respective contributions of photocatalysis and extracellular respiration to the synergistic effect by the interaction between hematite and S. oneidensis will be studied from the perspectives of the electrogenesis of S. oneidensis and the semiconducting properties of hematite. The roles of the outer-membrane c-type cytochromes, OmcA and MtrC, bio-engineered S. oneidensis MR-1, as well as the synthetic microbial community including S. oneidensis MR-1in the synergy of electrogenesis and photocatalysis will be studied. The band gap of hematite will be adjusted by doping Al or Mn, in order to improve the visible-light response. In addition, flavins will be used as the photosensitizer to modify the semiconducting properties of hematite. The photocurrents by the system of modified hematite and S. oneidensis will be investigated, in order to reveal the effects of semiconducting properties on the synergetic effects of hematite and S. oneidensis under visible-light irradiation. The effects of the studied system on environmental treatments and element biogeochemical cycling in hydrosphere will be discussed based on the mechanisms.