Optimization of Cadmium Biosorption by Cadmium Tolerant Bacteria Isolated from Industrial Effluents

Abstract

Environmental pollution with cadmium (Cd⁺²), presents serious health hazards as well as environmental issues. The main objective of this study was to check the optimum physiological conditions for Cd⁺² biosorption by the bacteria isolated from industrial effluents. Minimum inhibitory concentration (MIC) of Cd⁺² for the bacterial isolates was determined for the screening of the bacteria. Out of all the bacterial isolates, RNLI S1 had the highest MIC value equal to 600 µg/ml. RNMD S3 and RNLI S2 showed the same MIC values equal to 550 µg/ml, which was the second highest value. The MIC values of the bacterial isolates RNMD S4 and RNMD S5 were 500 and 450 µg/ml, respectively. RNLI S6 has the lowest MIC value among all the bacterial isolates which was equal to 400 µg/ml. Three bacterial isolates RNLI S1, RNMD S2, and RNLI S3 were selected for further experiments based on their MIC values. The optimization of physiological parameters such as temperature and pH for cadmium biosorption ability of these bacteria was carried out. Cadmium biosorption potential of RNMD S2 (92.04%) and RNLI S3 (90.81%) was maximum at 45℃, whereas RNLI S1 (88.38%) showed maximum biosorption at 37℃. Optimum pH for maximum cadmium biosorption was 9 for RNMD S2 (80.65%) and RNLI S3 (79.16%) and for RNLI S1 (80.31%) it was found to be 7.  The findings of this study highlight the potential of these bacterial isolates, RNLI S1 (Pseudomonas sp.), RNMD S2 (Micrococcus sp.) and RNLI S3 (Acinetobacter sp.) in the application of cadmium bioremediation at various contaminated sites.