Mercury bioremediation assay. Growth of untransformed E. coli bacteria in media without HgCl2, with 120 μM HgCl2, and in treated medium was measured after a 16 hours culture period at 37°C. The untransformed bacteria was inoculated to an initial absorbance of 0.01. Treated medium was LB culture media that was initially amended with 120 μM HgCl2, inoculated with mt-1 transgenic bacteria, and allowed to grow for 120 hours. After the 120 hours, the mt-1 transgenic bacteria was removed from the LB media by centrifugation and filter sterilization. Growth was determined by measuring absorbance at 600 nm.