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Cadmium is an important toxic environmental heavy metal. Environmental pollution with cadmium results mainly from mining, industry of batteries and pigments. In a human body, cadmium exposures have been associated with cancers of the prostate, lungs and testes. This study reports the design of high-performance biosorbents by means of incorporating novel binding sites in peptides of Escherichia coli for a particular metal ion Cd2+. E. coli was used for
genetic recombination due to its genetic simplicity. The maltose binding protein MalE, a part of the maltodextrin transport system in E. coli, was used as a anchoring motif which is encoded in pMAL-p2. In this study, SYN-9Glu containing 9 glutamic acids and SYN-11His containing 11 histidines from SYN-9Cys which enhanced uptake of Cd2+ were successfully fused to the MalE protein. After recombination of the gene, analysis of DNA was carried out by gel elcetrophoresis.
The cadmium sorption capacity of genetically engineered biosorbents was found to be 1.5 times higher than that of raw biomass at pH 5.0. The mutant E. coli could adsorb up to 33 mg of Cd2+ per g of dried cells.