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Honolulu, HI, United States, 2006/08/23 - Some microbes are able to tolerate radioactivity and other toxic environments because they developed detoxification mechanisms that allow them to resist adverse environments without being damaged..
These protective mechanisms increasingly are of great interest to scientists not only for developing innovative remediation strategies but also for creating novel biotechnological applications. As a recent example, researchers in Germany managed to produce highly stable and regular palladium (Pd) nanoparticles by harnessing the survival mechanism of bacteria found in uranium-polluted waste. These particles showed much improved catalytic activity and other new physical properties, which make them ideal for use as nanocatalysts or nanosensors.
Back in 1997, a team of biologists from the Institute of Radiochemistry at the Forschungszentrum Rossendorf (FZR) in Dresden, Germany, discovered a microbe called Bacillus sphaericus JG-A12 in the waste of an uranium mining site. JG-A12 exhibits a high metal-binding capacity, indicating that it might provide a protective function by preventing the cellular uptake of heavy metals and radionuclides.
The researchers working on interactions of actinides with biomolecular surfaces found that JG-A12 protects itself from the toxicity of uranium by selectively binding large amounts of the toxic metal on its protective protein surface layer (S-layer). The S-layers are surface structures of bacteria that form highly regular protein lattices, covering the whole cell. The lattice pores measure only a few nanometers.
Dr. Sonja Selenska-Pobell, the group leader Molecular Microbiology in the Institute of Radiochemistry at the FZR, explained the recent findings to Nanowerk: "Although JG-A12's properties allowed us to use S-layers as self-assembling organic templates for the synthesis of heavy metal nanocluster arrays, we knew little about the molecular basis of the metal-protein interactions and their impact on secondary structure."
In recent work ("Secondary Structure and Pd(II) Coordination in S-Layer Proteins from Bacillus sphaericus Studied by Infrared and X-Ray Absorption Spectroscopy"), Selenska-Pobell and her colleagues localized the sites on the S-layer protein of JG-A12 that are involved in the metal complexation.
Read the full article on the Nanowerk website.
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By Michael Berger, Copyright 2006 Nanowerk LLC