Uranium mining waste pile isolate Bacillus sphaericus JG-A12 and its technological applications

The strain Bacillus sphaericus JG-A12 was isolated from a uranium mining waste pile near the town of Johanngeorgenstadt. The drain water and the soil of this environment are highly contaminated with heavy metals and radionuclides. The cells of B. sphaericus JG-A12 are capable of selective and reversible accumulation of U, Cu, Pb, Al, and Cd from the U waste waters (1). It was demonstrated that the strain JG-A12 is enveloped by a surface layer protein (S-layer) which differs significantly in its primary structure from the other B. sphaericus S-layers studied up to date (2). The highly ordered crystalline S-layers are one of the most common cell envelope structures of bacteria and archaea (3). They are composed of identical protein monomers which possess an ability to self-assemble into two-dimensional crystalline arrays. The highly regular structure of the S-layers with many pores of identical size offers good binding sites for many different metals and nucleation sites for the formation of metal nanoclusters or minerals. EXAFS-analyses of the uranium complexes formed by the S-layer of JG-A12 showed that this metal is coordinated to carboxyl and phosphate groups of the latter (4). Analyses of the amino acid composition of the C-terminus showed a high content of serine and treonine residues which are potential phosphorylation sites. These characteristic features of the S-layer of B. sphaericus JG-A12 make the strain perspective for bioremediation and nanotechnological applications.
In this work we are presenting the formation of Pd nanoclusters on the cells of B. sphaericus JG-A12 in the presence of H2 as a reducing agent. These nanoclusters are interesting for the development of bionanocatalysts and biosensors. Further, by embedding cells, spores or S-layers using sol-gel techniques bioceramics particles were produced (5, 6). These bioceramics can be used for bioremediation of heavy metal contaminated waters.

References
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2. Raff, J. (2002) "Wechselwirkungen der Hüllproteine von Bakterien aus Uranabfallhalden mit Schwermetallen" PhD thesis, FZR-Report No. 358.

3. Sleytr, U. et al. (1997) FEMS Microbiol. Rev. 20, 47-97.
4. Merroun M. et al. (2003) FZR-Report No. 364, p. 26-30
5. Raff, J. et al. (2003) Chem. Mater. 15 (1): 240-244.
6. Soltmann et al. (2003) J Sol-Gel Science and Technology 26, 1209-1212.