US Patent 7452703 Uranium enrichment using microorganisms

The present invention provides methods for separating isotopes of actinide elements such as uranium using microorganisms, e.g., metal or sulfate reducing bacteria. The microorganisms reduce the actinide element to form a precipitate, which contains a greater proportion of the lighter isotope relative to the heavier isotope than the starting material. The precipitate may be collected, re-oxidized, and subjected to multiple rounds of enrichment. Alternately, separation processes not requiring formation of a precipitate may be used. The invention also features cell-free systems for isotope separation. The invention further provides compositions produced according to the foregoing methods, including compositions comprising enriched uraninite.