Heavy metals uptake by Euglena proxima isolated from tannery effluents and its potential use in wastewater treatment

The flagellate, Euglena proxima , isolated from industrial wastewater showed tolerance against Cr 6+ (20 μg/ml) and Pb 2+ (30 μg/ml). The metal ions slowed down the growth of the organism after 4–5 days of exposure. The reduction in cell population was 68% for Cr 6+ and 59% for Pb 2+ after 8 days of metal stress. The order of resistance to heavy metals, in terms of reduction in the cellular population, was Pb 2+ > Cr 6+ . Chromium and lead processing capabilities of Euglena proxima were worked out for its potential use as biore-mediator of wastewater. The reduction in the amount of Cr 6+ after 7, 14 and 21 days of flagellate culturing containing 5 μg Cr 6+ /ml of culture medium was 76, 80 and 88%, respectively. Euglena proxima could also remove 78% Pb 2+ after 7 days, 82% after 14 days and 90% after 21 days from the culture medium. The acid digestion of Euglena proxima showed 84% of Cr 6+ and 88% of Pb 2+ ions accumulated in the organism. The heavy metal uptake ability of Euglena proxima can be exploited for metal detoxification and environmental clean-up operations.