Name: how microbes lock up uranium in soil
Uploaded: 2026-03-12T13:57:45.000Z
Duration: 1 min 25 s
Channel: JoVE

Microorganisms immobilize uranium from contaminated environments by transforming it into less soluble forms through mechanisms such as bioreduction, biosorption, bioaccumulation, and biomineralization.Hexavalent uranium is water-soluble, which migrates easily through groundwater and contaminates surrounding areas. In bioreduction, microbes such as Geobacter and Shewanella use their c-type cytochromes to convert hexavalent uranium into a tetravalent form.The tetravalent uranium then precipitates as solid uraninite, reducing its mobility and containing the contamination.Biosorption involves the passive binding of uranium ions to functional groups such as carboxyl, phosphate, and hydroxyl groups on microbial surfaces, reducing the contamination.In bioaccumulation, microbes absorb uranium and transport it inside their cells, where it is stored, often bound to polyphosphate granules.Some microbes, including Microbacterium and Caulobacter, trigger biomineralization by enzymatically releasing phosphate, which reacts with uranium ions to form stable uranium-phosphate minerals.

microbial bioremediation of uranium

Microbial Bioremediation of Uranium

Microorganisms play a critical role in the transformation and immobilization of uranium in contaminated environments through four main pathways: bioreduction, biosorption, bioaccumulation, and biomineralization. These mechanisms reduce uranium&#8217;s toxicity and prevent its migration through groundwater systems, offering sustainable approaches for in situ bioremediation.Bioreduction of UraniumBioreduction is driven by anaerobic bacteria such as certain strains of Geobacter and Shewanella, which use U(VI) as a terminal electron acceptor. Through complex electron transport systems involving c-type cytochromes (e.g., OmcA, MtrC), these microbes enzymatically reduce soluble and mobile U(VI) to insoluble U(IV), precipitating as uraninite (UO&#8322;). Environmental conditions such as pH, presence of acetate or other electron donors, and the specific cytochrome composition influence the efficiency of this process. Desulfovibrio species, particularly under sulfate-reducing conditions, also facilitate U(VI) reduction via cytochromes such as cytochrome c&#8323;.Biosorption and BioaccumulationBiosorption involves passive binding of uranium to functional groups like carboxyl, hydroxyl, and phosphate moieties on microbial cell surfaces. This non-metabolic process is effective even in dead biomass. On the other hand, bioaccumulation requires active or facilitated uptake of uranium into cells, often followed by intracellular binding or precipitation. Notably, acidophilic and alkaliphilic strains from uranium-contaminated environments show variation in uranium uptake and retention capacity depending on external conditions.Biomineralization via PhosphatasesBiomineralization relies on the enzymatic release of phosphate, which reacts with uranyl ions to form stable minerals such as autunite. Phosphatases&#8212;especially acid phosphatases like PhoN&#8212;mediate this process. Studies highlight the role of strains such as Serratia, Caulobacter, and Microbacterium in facilitating uranium-phosphate precipitation, even under low uranium concentrations (&lt;1 &#181;M), relevant to environmental standards. The location and efficiency of mineralization vary with pH and phosphate availability, emphasizing the adaptability of microbial pathways in diverse geochemical settings.

Microorganisms play a critical role in the transformation and immobilization of uranium in contaminated environments through four main pathways: ...

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how microbes lock up uranium in soil

Microbes can help lock up uranium in contaminated soil and water. They do this through bioreduction, biosorption, bioaccumulation, and biomineralization. These pathways lower uranium toxicity and help stop it from moving through groundwater.

Bioreduction is one of the main microbial pathways. Anaerobic bacteria such as some Geobacter and Shewanella strains use U(VI) as a terminal electron acceptor. Their c-type cytochromes, including OmcA and MtrC, help convert soluble, mobile U(VI) into insoluble U(IV), which can form uraninite (UO2). Conditions such as pH, acetate or other electron donors, and the cytochrome mix can affect how well this works. Desulfovibrio species can also reduce U(VI), especially under sulfate-reducing conditions, with cytochromes such as cytochrome c3 involved.

Biosorption and bioaccumulation remove uranium in different ways. Biosorption is a passive process in which uranium binds to cell-surface groups such as carboxyl, hydroxyl, and phosphate moieties. It can work even with dead biomass. Bioaccumulation is different because it needs active or facilitated uptake into the cell, followed by intracellular binding or precipitation. Acidophilic and alkaliphilic strains from uranium-contaminated sites can vary in how much uranium they take up and keep, depending on outside conditions.

Biomineralization uses enzymes called phosphatases to release phosphate. The phosphate then reacts with uranyl ions to form stable minerals such as autunite. Acid phosphatases like PhoN are important in this pathway. Strains such as Serratia, Caulobacter, and Microbacterium have been shown to drive uranium-phosphate precipitation even at low uranium levels below 1 µM. The exact location and speed of mineral formation depend on pH and phosphate availability, which shows how flexible these microbial pathways can be in different geochemical settings.

How Microbes Lock Up Uranium in Soil

Microbes can help lock up uranium in contaminated soil and water. They do this through bioreduction, biosorption, bioaccumulation, and biomineralization. These pathways lower uranium toxicity and help stop it from moving through groundwater. Bioreduction is one of the main microbial pathways. Anaerobic bacteria such as some Geobacter and Shewanella strains use U(VI) as a terminal electron acceptor. Their c-type cytochromes, including OmcA and MtrC, help convert soluble, mobile U(VI) into...

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key terms and concepts

Learn how microbes reduce uranium mobility through bioreduction, biosorption, bioaccumulation, and biomineralization in contaminated environments.

How Microbes Lock Up Uranium in Soil | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

How Microbes Lock Up Uranium in Soil

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