Method for producing metal nanoparticles and metal sulfide nanoparticles using a recombinant microorganism

A method for producing single-element metal nanoparticles, comprising the steps of:

• (a) culturing a recombinant E. coli bacterium into which a metallothionein-encoding gene and a phytochelatin synthase-encoding gene have been introduced, in a medium at pH of 6 to 7, to induce expression of metallothionein and phytochelatin synthase in the recombinant E. coli bacterium, wherein the metallothionein-encoding gene has the nucleotide sequence of SEQ ID NO:
• 1 and the phytochelatin synthase-encoding gene has the nucleotide sequence of SEQ ID NO:
• 2;
• (b) increasing pH of the medium of step (a) to pH of 7.3 to of 7.7, and adding to the medium a metal ion selected from the group consisting of zinc (Zn), nickel (Ni), cobalt (Co), cadmium (Cd), praseodymium (Pr), gadolinium (Gd), lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), and europium (Eu), followed by additional culturing;
• (c) after the additional culturing of step (b), increasing pH of the medium of step (b) to pH of 8.0 to 9.0, to produce single-element metal nanoparticles;
• and
• (d) recovering the produced single-element metal nanoparticles.