Removal of Au(III) from Aqueous Au(III) Solution Using Microbial Cells by Biosorption and Biomineralization

The demand for gold has increased in the medical and industrial fields. Therefore, recycling this element has become essential. Although gold recovery using microbes has been investigated, there is a dearth of these studies on identifying the species that have a high gold recovering ability. Herein, gold (III) removal by microbial cells was investigated to obtain basic information on gold (III) removal from aqueous systems by biosorption and biomineralization. High amounts of gold were removed from the solution containing hydrogen tetrachloroaurate (III) by the tested microbial species, which included bacteria, fungi and yeasts. However, relatively less gold was recovered by biosorption using gram-positive bacteria, fungi, and yeasts than that by gram-negative bacteria. Therefore, we first examined gold (III) removal by biosorption and biomineralization by Pseudomonas saccharophila, which was able to remove the largest amounts of gold (III). Incubation time and other factors affecting gold removal were then examined. P. saccharophila removed about half the amount of gold (III) by biosorption and the remaining half by biomineralization.