Metabolic Engineering for Heavy Metal and Actinide Removal

摘要

Engineering hydrogen sulfide production and cadmium removal by expression of the thiosulfate reductase gene (phsABC) from Salmonella enterica serovar Typhimurium in Escherichia coli. The thiosulfate reductase operon (phsABC) from Salmonella typhimurium was expressed in Escherichia coli to overproduce hydrogen sulfide from inorganic thiosulfate for heavy metal removal (or precipitation). A 5.1-kb DNA fragment containing the native phsABC was inserted into the pMB1-based high-copy, IPTG-inducible expression vector pTrc99A and the RK2-based, medium-copy, m-toluate inducible vector pJB866, resulting in plasmids pSB74 and pSB77, respectively. A 3.7-kb DNA fragment, excluding putative promoter and regulatory regions, was inserted into the same vectors making plasmids pSB 103 and pSB 107, respectively. E. coli DH5a harboring the phsABC constructs showed higher thiosulfate reductase activity and produced significantly more sulfide than the control strains under both aerobic and anaerobic conditions.