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Abstract：
Uranium (U) pollution is an environmental hazard caused by the development of the nuclear industry. Microbial reduction of hexavalent uranium (U(VI)) to tetravalent uranium (U(IV)) reduces U solubility and mobility and has been proposed as an effective method to remediate uranium contamination. In this review, U(VI) remediation with respect to U(VI)-reducing bacteria, mechanisms, influencing factors, products, and reoxidation are systematically summarized. Reportedly, some metal- and sulfate-reducing bacteria possess excellent U(VI) reduction capability through mechanisms involving c-type cytochromes, extracellular pili, electron shuttle, or thioredoxin reduction. In situ remediation has been demonstrated as an ideal strategy for large-scale degradation of uranium contaminants than ex situ. However, U(VI) reduction efficiency can be affected by various factors, including pH, temperature, bicarbonate, electron donors, and coexisting metal ions. Furthermore, it is noteworthy that the reduction products could be reoxidized when exposed to oxygen and nitrate, inevitably compromising the remediation effects, especially for non-crystalline U(IV) with weak stability.
摘要：
铀（U）污染是核工业发展引起的环境危害。微生物将六价铀（U（VI））还原为四价铀（U（IV））会降低U的溶解度和迁移率，并已被提出作为修复铀污染的有效方法。在这次审查中,U（VI）对U（VI）还原细菌的修复，机制,影响因素，产品,并对再氧化进行了系统总结。据报道,一些金属和硫酸盐还原细菌通过涉及c型细胞色素的机制具有优异的U（VI）还原能力，胞外菌毛，电子穿梭机,或硫氧还蛋白减少。与非原位相比，原位修复已被证明是大规模降解铀污染物的理想策略。然而,U(VI)还原效率会受到各种因素的影响，包括pH值,温度,碳酸氢盐,电子供体,和共存的金属离子。此外，值得注意的是，当暴露于氧气和硝酸盐时，还原产物可能会被再氧化，不可避免地损害了补救效果，特别是对于具有弱稳定性的非晶体U(IV)。
