A method is provided which uses existing populations of soil bacteria to produce quantities of melanin and pyomelanin and related pigments which will chemically reduce and chelate metals and sorb to various soil minerals to help immobilize such metals within a subsurface environment. Tyrosene and phenylalanine may be used to generate enhanced levels of melanin.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
 This invention was made with Government support under Contract No. DE-AC09-96SR18500 awarded by the United States Department of Energy. The Government has certain rights in the invention.