Abstract
A novel method using the mesophilic anaerobic bacterium Shewanella algae was proposed to recover gold dissolved in aqueous solutions. The anaerobic bacterium was capable of precipitating gold particles by reducing Au(III) ions in aqueous HAuCl4 solutions with molecular hydrogen as the electron donor. In the presence of S. algae cells and hydrogen gas, the Au(III) ions in the solutions were almost completely reduced and precipitated from 1 mol/m3 aqueous HAuCl4 solution within 60 min at room temperature. The formation of gold nanoparticles was also evidenced by the color change of the suspension (the surface plasmon absorption of gold nanoparticles). The TEM observations revealed that the microbially induced gold nanoparticles adheres to the bacterial cells. These results demonstrate that the gold-reducing bacterium S. algae has the very attractive ability to recover gold from aqueous solutions without using excess energies and chemicals in order to prevent further environmental contamination.
