Copper Adsorption Potentiality of Bacillus stercoris GKSM6 and Pseudomonas alcaliphila GKSM11 Isolated from Singhbhum Copper Mines

Increasing industrial activities, mining deposits, excessive use of hazardous chemicals, and waste discharges are the driving forces for emerging copper (Cu) contamination. In the present study, two highly Cu-tolerant bacterial isolates, Bacillus stercoris GKSM6 and Pseudomonas alcaliphila GKSM11, were isolated, characterized, and investigated for their copper sorption potential. The Cu2+ tolerable concentrations were found to be 350 mg/L for strain GKSM6 and 400 mg/L for strain GKSM11. The maximum copper uptake capacity of GKSM6 was found to be 35.05 mg/g, whereas it was 31.15 mg/g in case of GKSM11 at optimum conditions of pH 7.0, temperature 35 °C for 24 h. The equilibrium data was well fitted with the Langmuir isotherm model (R2 = 0.9851 for B. stercoris and R2 = 0.9954 for P. alcaliphila), indicating a homogenous monolayer adsorption pattern. Electron microscopic analysis confirmed the immobilization of copper ions on the bacterial cell surface. The EDS peak also showed the surface sorption of copper ions, which was confirmed by the presence of various functional groups like carboxyl, hydroxyl, amine, and phosphate. In this prospect, the novelty of this study relies on the biosorption of Cu2+ using Singhbhum copper mines inhabiting bacterial isolates pay as a possible option for the amelioration of copper-contaminated sites.