Taste for nuclear waste

Taste for nuclear waste scientists in Germany have isolated a strain of bacteria from a uranium waste pile, which can be used to clean up toxic dumps.

Bacillus sphaericus jg -a12 survives in highly toxic environments by accumulating heavy metals such as uranium, cadmium and lead in its outermost layer, according to the group of researchers from the Institutes of Radiochemistry and Nuclear Physics in Dresden. Their study will appear in a forthcoming issue of Biotechnology Advances. Deciphering the mechanisms of such adaptation will lead to development of bioremediation techniques and other applications.

With the increase in generation of nuclear power and nuclear weapons, waste piles of radionuclides like uranium will continue to accumulate, posing a serious health and ecological hazard. A single uranium mine can generate as much as 230,000 tonnes of nuclear waste over 30 years.

This particular strain of bacteria has evolved a crystalline surface layer (s-Layer), which acts not only as a protective barrier but also a sponge to accumulate and immobilise high concentrations of toxic metals. According to the study, uranium binds to the phosphate group of the s-Layer protein. B sphaericus jg -a12 contains six times more phosphorus (than that found in other strains of the bacterium), which reflects an adaptation of the strain to uranium-contaminated environments.

"Identifying the process is the first step but these processes are slow in nature. The next step is to replicate the process in the laboratory to hasten it,' says K A Natarajan, professor of metallurgy at the Indian Institute of Science in Bangalore.

Researchers are now trying to envelop silicon wafers, polymers and bio-ceramic discs in the s -Layer, which could then be used to remove metals from contaminated soil and water. "Although there is a chemical answer to everything, biological remediation is the best and cheapest answer,' says Natarajan.

The strain can also be used to recover precious metals such as platinum and palladium from industrial waste sites and to make nanoparticle arrays, which have many industrial applications, such as catalysts.

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