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

Abstract

The flagellate, Euglena proxima, isolated from industrial wastewater showed tolerance against Cr6+ (20 μg/ml) and Pb2+ (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 Cr6+ and 59% for Pb2+ after 8 days of metal stress. The order of resistance to heavy metals, in terms of reduction in the cellular population, was Pb2+ > Cr6+. 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 Cr6+ after 7, 14 and 21 days of flagellate culturing containing 5 μg Cr6+/ml of culture medium was 76, 80 and 88%, respectively. Euglena proxima could also remove 78% Pb2+ 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 Cr6+ and 88% of Pb2+ ions accumulated in the organism. The heavy metal uptake ability of Euglena proxima can be exploited for metal detoxification and environmental clean-up operations.