Gold biosorption by exopolysaccharide producing cyanobacteria and purple nonsulphur bacteria

Aims This study was aimed at investigating the possible exploitation of phototrophic micro-organisms for the removal and the recovery of Au from Au-containing wastewaters deriving from a plating industry. Methods and Results A screening among ten phototrophic micro-organisms was carried out with pure solutions of Au to select the best strain in terms of metal uptake and selectivity. The direct use of the selected micro-organism on the Au-containing industrial wastewater was then carried out with the aim of assessing the potential of its use for the removal and the recovery of the precious metal from industrial wastewaters. Conclusions This study showed the good potential of some exopolysaccharide-producing cyanobacteria as biosorbents for the recovery of Au from wastewaters of plating industries but also pointed out the need to design an efficient technology for the recovery of the metal from the biomass. Significance and Impact of the Study The selection of good biosorbents for the recovery of gold from industrial wastewaters may open new perspectives to a green biotechnology so far considered too expensive for the mere treatment of wastewaters containing low valuable metals.