Chromate Reduction by Purple Non Sulphur Phototrophic Bacterium Rhodobacter sp. GSKRLMBKU–03 Isolated from Pond Water

A purple non sulphur phototrophic bacterium (PNSB) Rhodobacter sp. GSKRLMBKU–03 was isolated from pond water of Thadoba forest, Chandrapoor District, India and its ability to reduce hexavalent chromium was discussed in the present study. Both free and immobilized cells of this bacterium were employed for chromate reduction. Immobilization of cells resulted in enhanced reduction of chromate. Sodium alginate entrapment could reduce chromate up to 40 μM, while free cells of Rhodobacter sp. GSKRLMBKU–03 could reduce about 35 µM of chromate on 8th day of its incubation under anaerobic light conditions. Both free and immobilized cells could reduce chromate even on the 20th day. Optimal growth and chromate reduction was observed on 8th day of its incubation period. The final pH of the free cells and immobilized cells in growth medium was recorded in the range of 7.5 ± 0.25–7.6 ± 0.15 at optimal incubation period respectively. The optimal growth of free cells and immobilized cells in terms of dry cell weight (DCW) was recorded as 1.80 ± 0.15 and 2.2 ± 0.20 g/L respectively. The optimal growth observed upon complete chromate reduction. The results are expressed in mean and standard deviations which are statistically significant at P ≤ 0.05 level. The employment of Rhodobacter sp. in bioremediation to detoxify chromium in large-scale systems is proposed.