Uranium bioremediation with U(VI)-reducing bacteria

• Published in: The Science of the total environment 2021-12, Vol.798, p.149107-149107, Article 149107
• Main Authors: You, Wenbo, Peng, Wanting, Tian, Zhichao, Zheng, Maosheng
• Format: Article
• Language: English
• Subjects: Bioremediation; C-type cytochromes; Microbial uranium reduction; Reoxidation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.149107

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. [Display omitted] •The mechanisms for microbial U(VI) reduction are reviewed.•Microbial reduction U(VI) to U(IV) reduces U solubility.•Efficiency can be affected by pH, temperature, and electron donors.•Reduction products could be reoxidized due to oxygen and nitrate.•In situ remediation is better than ex situ process.