A Newly Acidophilic Bacterium Acidomyces acidothermus Was Isolated to Efficiently Bioleach Copper from Waste Printed Circuit Boards (WPCBs)

An acidophilic metal-resistant bacterial strain, Acidomyces acidothermus (A. acidothermus), was isolated and identified by morphology, physiology, biochemistry, and 16S rDNA. A. acidothermus culture conditions were optimized by response surface methodology (RSM). Results showed that with a temperature of 40 °C, a pH of 3 in a 9k medium, and a rotation speed of 140 r/min, the copper leaching rate reached the highest value of 39.8%. Furthermore, SEM images and a heatmap of differential metabolites indicated that A. acidothermus adsorbed on the surface of WPCBs and extracellular polymeric substances (EPS), mainly D-glucuronic acid, were secreted, suggesting the highly efficient mechanism of copper recovery from WPCBs.