Expression of Rhizobium tropici phytochelatin synthase in Escherichia coli resulted in increased bacterial selenium nanoparticle synthesis

Phytochelatins are the main heavy metal detoxifying peptides found in plants. In the present study, Escherichia coli DH5α cells were transformed with the phytochelatin synthase gene from Rhizobium tropici. The tolerance of these recombinant bacterial cells to heavy metals as well as their capacity to synthesize selenium nanoparticles were explored. The functional studies showed the recombinant E. coli grew faster and achieved a higher cell density after overnight cultivation in comparison with the control cells. In addition, the recombinant E. coli had a higher tolerance to copper, nickel, zinc, and cadmium ions. Importantly, the cells had increased capacity to synthesize selenium nanoparticles. Our results suggested that the phytochelatin synthase gene transformed E. coli DH5α cells can be used to produce selenium nanoparticles in large scale for various applications in nanotechnology and biomedicine.