Study of Copper Bioremediation by Planktonic Cells and Biofilms of Bacteria Isolated from Indigenous Environment

Abstract

This research aimed to isolate copper-resistant bacteria from industrial effluents for potential bioremediation in both planktonic and biofilm growth modes. Out of ten isolates from industrial effluents, four bacterial strains (S1A, S2C, SSA, and S1C) wereselected based on their minimum inhibitory concentration (MIC) and biofilm-forming capabilities. These bacteria demonstrated strong biofilm formation abilities in both the absence and presence of copper (Cu) stress, with MIC values of 850 μg/ml for S1A, SSA, and S1C, and 750 μg/ml for S2C. Physiological characterization revealed that these isolates exhibited optimal growth at pH 7 and 37°C. Biochemical characterization indicated the similarity of these copper-resistant bacteria with the genera Staphylococcus (S1C), Bacillus (SSA), Corynebacterium (S1A), and Enterobacter (S2C). The copper removal efficiency of these isolates was assessed in both planktonic and biofilm growth modes using atomic absorption spectroscopy. In planktonic growth, all isolates showed copper removal efficiencies of 81.4% (S1A), 81% (SSA), 83.5% (S2C), and 82.3% (S1C) after 24 hours, and 84% (S1A), 83.4% (SSA), 85.3% (S2C), and 84.2% (S1C) after 48 hours. Notably, in planktonic growth, S2C (Staphylococcus) exhibited the highest removalefficiency, with 83.5% and 85.3% after 24 and 48 hours, respectively. In the biofilm growth mode, copper removal efficiencies were 84.2% (S1A), 82.7% (SSA), 81.9% (S2C), and 84% (S1C) after 24 hours, and 86.7% (S1A), 86.1% (SSA), 85.6% (S2C), and 86.2% (S1C) after 48 hours. Notably, S1A (Corynebacterium) displayed the highest copper removal efficiency, with 84.2% and 86.7% after 24-and 48-hour incubation in biofilm growth modes.KEYWORDSAtomic absorption spectrophotometer, Biofilms, Bioremediation, Minimum inhibitory concentration.