Interactions of the U mining waste pile isolate Bacillus sphaericus JG-A12 with U

Apart from chemical and physical factors influencing mobility of radionuclides, microbial metabolism also plays a decisive role in enhancing or retarding migration effects. Bacteria are able to reduce or oxidize metals and also to accumulate and bind them. In this work biosorption of U by cells, spores and S-layers of a U mining waste pile isolate Bacillus sphaericus JG-A12 was investigated. Furthermore, these three bacterial structures were used for construction of porous biocomponent-silicate hybrids referred to as biological ceramics (biocers) for bioremediation. The results show the highest binding capacity for the spores followed by the cells and the S-layer sheets. The silicate matrix itself binds only small amounts of U. Sol-gel encapsulation does not affect the U binding properties of the cells or the S-layer sheets but strongly reduces the binding capacity of the spores. Spectroscopic analyses of the U complexes demonstrate that U is bound to phosphate and carboxyl groups of the biocomponents and to silanol groups of the silicate matrix.