Cadmium, lead, and zinc removal by expression of the thiosulfate reductase gene from Salmonella typhimurium in Escherichia coli

The thiosulfate reductase gene (phsABC) from Salmonella typhimuriumwas expressed in Escherichia coliin order to produce sulfide from inorganic thiosulfate and precipitate metals as metal sulfide complexes. The sulfide-engineered strain removed significant amounts of heavy metals from the medium within 24 h: 99% of zinc up to 500 M, 99% of lead up to 200 M, 99% of 100 M and 91% of 200 M cadmium. In a mixture of 100 M each of cadmium, lead, and zinc, the strain removed 99% of the total metals from solution within 10 h. Cadmium was removed first, lead second, and zinc last. These results have important implications for removal of metals from wastewater contaminated with several metals.