Deep underground, bacteria may offer a new answer to uranium contamination. In a 130-day laboratory experiment, microbes fed with glycerol removed about 95% of dissolved uranium from contaminated mine water. The bacteria did more than trap the radioactive metal. They helped form FeU(V)O₄, a rare and unusually stable uranium compound. The finding could reshape research into uranium bioremediation, groundwater cleanup, and radioactive waste control.