Responses exhibited by various microbial groups relevant to uranium exposure

This review explores the responses of various microbial systems to uranium exposure, primarily in the context of bioremediation. While there is no established biological role for uranium, it is naturally found in rocks and minerals. The insolubility of U(IV) minerals limits uranium's bioavailability. However, human activities have introduced soluble and toxic forms of uranium into the environment. Microorganisms exhibit a range of responses to uranium, including adsorption, accumulation, reduction, oxidation, respiration, mineralization, and precipitation. This paper focuses on three key bioprocesses: biosorption, bioprecipitation, and bioreduction, highlighting the microbial groups involved and their inherent and engineered abilities for uranium removal. Field trials for in situ uranium bioremediation are also discussed. Furthermore, advances in genomics and proteomics are presented, shedding light on regulatory and physiological determinants in microbes responding to uranium stress. The review includes recent developments in metagenomics and metaproteomics that underscore the ecologically relevant traits necessary for microbial adaptation and survival in uranium-contaminated environments.