Effect of Growth in Metal-Augmented Media on Metal Resistance of Bacteria

This study investigates the effect of growth in metal-augmented media on metal resistance of bacteria isolated from contaminated soil. Total bacterial count of the soil sample carried out using serial dilution and pour plate method on nutrient agar medium was 1.9×105cfu/g while in copper sulphate (CuSO4) medium the was no visible growth. Bacterial isolates identified were Bacillus sp, Pseudomonas sp, Micrococcus sp and Clostridium sp. The frequency of occurrence of bacterial isolate recorded shows that Bacillus sp had (47.5%), Pseudomonas sp (27.5%), Micrococcus sp (15.0%) and Clostridium sp (10.0%). The efficiency of metal resistance of the bacterial culture was determined by inoculating the isolates into six different test tubes containing metal-augmented media (CuSO4 and FeSO4), and determine the culture pH and turbidity changes, and total bacterial count (TBC) at 3 days interval for 9 days. Result shows pH changes of 6.49 to 6.98, 6.51 to 6.94, 6.45 to 6.95, 6.45 to 7.00, 6.40 to 6.94 and 6.41 to 6.95 for F1mM, F2mM, F5mM, S1mM, S3Mm and S5mM respectively. Turbidity changes were 1.436 to 1.860, 0.800 to 1.279, 0.780 to 0.998, 1.279 to 1.976, 0.928 to 1.589 and 0.654 to 0.908 respectively. Total Bacterial Count were 6.0 x109 to 8.8 x109, 3.0 x109 to 5.5 x109, 0.9 x109 to 3.0 x109, 7.0 x109 to 9.5 x109, 4.0 x109 to 7.0 x109 and 1.2 x109 to 5.0 x109 respectively. Result reveal that 1% w/v of CuSO4 inhibit bacterial growth in culture. Additional, Bacillus was shown to possess metal resistance ability as seen in growth in FeSO4 and CuSO4 augmented culture.