Bacteria found in the flooded Wismut GmbH Schlema-Alberoda mine in Germany can convert toxic dissolved uranium into a stable chemical compound, according to research published in Nature Communications. By utilizing glycerol as a carbon source, these microbes transform uranium into a rare pentavalent state, allowing it to bond with iron and oxygen to form a stable mineral.
Microbes Turn Toxic Uranium into Stable Minerals
Researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the University of Granada discovered that specific bacteria in contaminated mine water don’t just survive radioactive environments—they actively alter the chemistry of the waste. According to microbiologist Evelyn Krawczyk-Bärsch of HZDR, the team found that bacteria supplied with glycerol can convert dissolved uranium into a stable compound.
The process centers on the “valency” of the uranium. While uranium typically exists in a valency of 4 or 6, these bacteria push it into a pentavalent state (+5). Antonio Newman-Portela, an HZDR microbiologist, noted that pentavalent uranium is usually rare or transient. In this specific biological environment, however, it becomes a bridge to create FeU(V)O4, a compound that locks the uranium into a stable mineral form.
Did you know? The Schlema-Alberoda mine was a major uranium operation in Soviet East Germany. Since its closure in 1990, the site has required continuous, costly water treatment to manage radioactive contamination.
The 130-Day Experiment: From Yellow Water to Black Precipitate
To test this, the HZDR and University of Granada teams used water samples from the treatment plant inlet of the Schlema-Alberoda mine. They simulated the low-oxygen conditions found at depths of 2,000 meters.
The results were visible. On day one, the incubated mine water appeared yellow. By day 130, the researchers observed a black precipitate forming at the bottom of the bottles, while the water above remained clear. Newman-Portela stated that only about five percent of the dissolved uranium remained in the water after 130 days.
The bacteria incorporated the uranium into their cell walls, where the high proportion of pentavalent uranium facilitated the formation of FeU(V)O4, especially when samples were dried and exposed to oxygen.
Scaling Bioremediation for Global Uranium Contamination
Uranium contamination isn’t limited to old German mines. According to the study authors, surface and groundwater in the United States, India, Canada, France, South Africa, and Australia have occasionally exceeded the 0.03 milligram per liter guidelines for uranium contamination.
The researchers suggest that “bioremediation”—using biological agents to clean the environment—could be a cost-effective alternative to traditional physico-chemical water treatment. The authors note that field studies using biological methods have already shown substantial uranium reduction without creating the secondary sludge often produced by chemical treatments.
Comparison: Biological vs. Physico-Chemical Treatment
| Feature | Physico-Chemical Treatment | Bioremediation (Bacterial) |
|---|---|---|
| Waste Product | Often generates secondary sludge | Avoids secondary sludge generation |
| Mechanism | Physico-chemical water treatment | Metabolic conversion to stable minerals |
Future Outlook for Nuclear Cleanup
While the results are promising, the transition from a lab bottle to a full-scale mine is complex. Krawczyk-Bärsch emphasized that the team must still investigate exactly how much these bacteria can help render uranium harmless for actual remediation purposes.
Because the identified processes are broadly applicable to other contaminated waters, this discovery could provide a blueprint for cleaning up radioactive sites worldwide.
Pro Tip: For those tracking environmental tech, keep an eye on “metabolic pathways.” The use of glycerol as a “food source” for these bacteria is the key trigger that allows them to process the uranium.
Frequently Asked Questions
What is pentavalent uranium?
It is uranium with an oxidation state of +5. It is typically rare or unstable, but in this study, bacteria used it to lock uranium into stable minerals like FeU(V)O4.
Where did the bacteria come from?
The bacteria were naturally occurring microbes collected from the treatment plant inlet of the Wismut GmbH Schlema-Alberoda mine in Germany.
Is this method ready for use in the wild?
Not yet. While the lab results show a 95% reduction in dissolved uranium, researchers are still studying the extent to which this can be scaled for practical remediation.
Why is glycerol important?
According to the HZDR researchers, the bacteria require glycerol as a carbon source to fuel the metabolism that allows them to convert the uranium.
What do you think about using bacteria to clean up radioactive waste? Could this be the future of environmental restoration? Let us know in the comments below or subscribe to our newsletter for more updates on biotech breakthroughs.
