Eco-friendly Copper Remediation through Optimized Biosorption by Industrial Effluent Bacteria

Abstract

Wastewater samples collected from the industrial area of Kot Lakh pat, Lahore, exhibited temperatures ranging from 35°C to 45°C and pH values between 8 and 9. A total of seven morphologically distinct bacterial isolates (ISO1-ISO7) demonstrating copper resistance were obtained from these samples. Minimum inhibitory concentration (MIC) analysis revealed variable tolerance levels, with ISO7 showing the highest resistance at 450 µg/ml, followed by ISO3 (410 µg/ml) and ISO6 (400 µg/ml). These three isolates were selected for further characterization. Physiological studies indicated optimal growth at 37°C and pH 9 for ISO3, and 45°C and pH 7 for ISO6 and ISO7. Biosorption assays demonstrated that temperature, pH, and incubation time significantly influenced copper uptake. Maximum Cu⁺² biosorption occurred at 25°C for ISO7 and at 37°C for ISO3 and ISO6, with peak uptake observed at pH 9 for ISO3 and ISO6 and at pH 7 for ISO7 after 48 h incubation. Biochemical profiling identified ISO3 as Enterococcus, ISO6 as Pseudomonas, and ISO7 as Salmonella. Growth promotion studies on wheat seeds revealed that all three isolates enhanced root and shoot lengths compared to controls, while co-application with copper mitigated the inhibitory effects of metal stress on germination. Overall, these results highlight the potential of copper-resistant bacteria for biosorption applications and plant growth promotion under metal stress, offering a sustainable approach for bioremediation of industrial effluents.