Interactions of the S-layer protein of the uranium waste pile isolate Bacillus Sphaericus SG A12 with metals

Bacteria in uranium waste piles are of special interest for bioremediation, because they are adapted to the high concentrations of radionuclides and heavy metals which occur in those environments. A large number of Bacillus strains was recovered from the uranium mining waste pile "Haberland" near the town of Johanngeorgenstadt in Saxony, Germany. One isolate, Bacillus sphaericus JG-A 12, possesses a surface layer protein with a molecular weight of 135 kDa [1]. Sequence analyses of this protein show that its primary structure differs significantly from those described for the B. sphaericus strains 2362, P-1 and CCM 2177 (EMBL Ac. Nos. M28361, A45814 and AF211170, respectively). However, the B. sphaericus JG-A 12 S-layer protein shares the N-terminal surface layer homology domain with the S-layer protein of B. stearothermophilus PV 72 p2 [2].
Fig. 1: TEM micrograph of the negatively stained na-tive surface layer, isolated from the uranium waste pile isolate Bacillus sphae-ricus JG-A 12.
Additionally one can see fragments of the bacterial flagellum (see the arrow).

The S-layer of B. sphaericus JG-A 12 has a p4 symmetry with a lattice constant of 12.5 nm [1]. S-layers may interact with different metal ions by forming metal clusters [3; 4; 5; 6]. We have demonstrated that the treatment of the native S-layer sheets of B. sphaericus JG-A 12 with Pt- or Pd-salt solutions leads to metal nanocluster formation. The latter is of great interest for the nanotechnology.
Vegetative cells and spores of B. sphaericus JG-A 12 are selectively accumulating large amounts of U, Pb, Cd, Cu and Al from the highly polluted drain waters of the above mentioned waste pile [7]. Using a sol-gel-process we have prepared a nanoscale bio-ceramic, which contains intact bacterial cells or extracted S-layer proteins. First results on heavy metal binding properties of this bio-ceramic will be presented.
References
[1] Raff, J. et al. (1999) 99TH General Meeting of the American Society for Microbiology,
May 30 - June 3, 1999, Chicago, Illinois, USA, J-12, p. 398
[2] Engelhardt, H. et al. (1998) Journal of Structural Biology 124, 276-302
[3] Brown A. D. et al. (1998) FEMS Microbiology Ecology 26, 297-310
[4] Diluweit, S. et al. (1998) Supramolecular Science 5, 15-19
[5] Pompe W. et al. (1999) Zeitschrift für Metallkunde 90 (12), 1085-1091
[6] Shenton W. et al. (1997) Nature 389, 585-587