细菌还原U(VI)分子生物学机理的研究进展

铀（U）污染对生态环境和人类健康的潜在危害受到越来越多的关注.U（VI）还原细菌可将U（VI）还原至U（IV），从而降低铀在水中的溶解性和移动性，达到污染修复的目的.目前发现的U（VI）还原细菌主要包括但不限于铁还原菌和硫酸盐还原菌.本文综述了细菌还原U（VI）的分子生物学机理，重点阐述了U（VI）还原细菌的胞外电子转移方式，包括希瓦氏菌的金属还原方式、土杆菌的孔蛋白介导方式和微生物纳米线方式.竞争性电子受体和共存离子对细菌还原U（VI）有重要影响.目前细菌还原U（VI）过程中胞外电子转移的机理仍需更多实证，土杆菌利用微生物纳米线和细胞色素协作调控电子转移的机制尚不明确.今后可将研究聚焦于细菌还原U（VI）机理的验证和完善，并开发和优化基于微生物还原的铀污染修复技术，进而提高铀污染生物修复效率和稳定性.

Review on the molecular mechanisms of U(VI) bioreduction

Uranium contamination is getting more and more attention due to its potential harm to environment and human health. Physical and chemical techniques are widely used in remediation, whereas generally expensive and challenging. Microbial mediated uranium bioreduction is an environmental-friendly technology, showing great potential in uranium remediation. Over the past twenty years, a diverse range of soil bacteria have been identified with the ability in reducing U(VI) to U(IV), including but not limited to Fe(III)-and sulphate-reducing bacteria. The recent progress in molecular mechanisms of bacterial U(VI) reduction was reviewed, especially the various pathways of extracellular electron transfer, including the metal-reducing pathway of Shewanella oneidensis MR-1, the porin-cytochrome-mediated pathway and nanowire pathway of Geobacter sulfurreducens PCA. Competitive electron acceptors and coexisting ions played important roles in bacterial U(VI) reduction. The molecular mechanisms by which bacteria transfer electrons across the outer membrane and then exchange electrons with extracellular minerals remain unclear. It also remains unclear how Geobacter spp. nanowires interact with the porin-cytochrome to transfer extracellular electron. In the future, studies could be focused on the mechanisms of bacterial U(VI) reduction and how to improve the efficiency and stability of uranium bioremediation.