A team of international scientists has discovered that naturally occurring bacteria can filter dissolved uranium out of polluted water locking it away into an incredibly stable, solid mineral structure in just 130 days. The study, published in Nature Communications offers a promising and highly durable breakthrough for the bioremediation using living organisms to clean up environmental pollution of former nuclear sites and heavy industry locations.
The research team, comprising experts from the Helmholtz Zentrum Dresden Rossendorf (HZDR), Wismut GmbH, and the University of Granada in Spain, isolated native bacterial strains directly from the flooded, oxygen-poor depths of a former uranium mine in Germany’s Ore Mountains. In laboratory simulations mirroring these natural, deep-underground conditions, the researchers introduced glycerol a cheap, carbon-rich byproduct of plant and animal fats as a nutrient source for the microbial community. Over a 130-day monitoring window, the bacteria metabolically consumed the glycerol and successfully precipitated the toxic heavy metal out of the liquid, leaving behind only 5% of the original dissolved uranium in the water samples.
Advanced synchrotron radiation and microscopic analysis revealed that the bacteria had effectively trapped the heavy metal within their own cell walls, but the true surprise lay in the precise chemical state of the captured material. Uranium typically exists in stable states with a valency the number of chemical bonds an atom can form of either 4 or 6. However, the bacteria forced the uranium into a rare, pentavalent state, binding it with iron and oxygen into a brand-new compound labeled .
While this specific mineral had been spotted once before in European soils contaminated by historic ammunition fire, scientists had no idea how it formed in nature. Crucially, the biological mineral proved to be remarkably resilient; even when the dried microbial mass was intentionally exposed to harsh atmospheric oxygen, the pentavalent uranium compound remained completely stable and did not re-dissolve into the environment. The HZDR research group is now launching follow up investigations to map the exact biochemical pathways driving this mineral crystallization, aiming to scale up the bacterial process into a cost effective, long term tool for safeguarding local water tables.