Microbial bioremediation of uranium mining waste waters using sol-gel ceramics

During the long period of uranium mining and production in Saxony, large amounts of ores were treated and leached. Waste piles and waste waters from those procedures with high concentrations of heavy metals and radionuclides still remain in this part of Germany. For further use of the mentioned areas, they have to be cleaned. For this purpose, bacteria recovered from the contaminated sites are very prospective, because developing detoxification strategies as binding or reduction of heavy metals and radionuclides, they are well adapted to the complex and toxic conditions in the wastes. Bacillus sphaericus JG-A12 was recovered form the uranium mining waste pile "Haberland" near the town of Johanngeorgenstadt. Vegetative cells and spores of this strain accumulate selectively and reversible large amounts of U, Cu, Pb, Cd and Al. Interestingly, B. sphaericus JG-A12 possesses a paracrystalline surface layer protein (S-layer) as outermost component of its cell wall. Compared to the known S-layers of the other B. sphaericus strains, the N-terminal domain of B. sphaericus JG-A12 S-layer possesses a novel primary structure. Cells, spores and stabilized S-layer sheets were embedded by sol-gel techniques in xerogels. The sorption and desorption of uranium and copper by the free biocomponents and the biocomposite material were investigated using EDX analysis.