Heavy metal resistant Distigma proteus (Euglenophyta) isolated from industrial effluents and its possible role in bioremediation of contaminated wastewaters

摘要

The alga, Distigma proteus, isolated from industrial wastewater showed tolerance against Cd2+ (8.0 μg/ml), Cr6+ (12 μg/ml), Pb2+ (15 μg/ml) and Cu2+ (10 μg/ml). The metal ions slowed down the growth of the organism after 4–5 days of exposure. The reduction in cell population was 90% for Cu2+, 84% for Cd2+, 71% for Cr6+, and 63% for Pb2+ after 8 days of metal stress. The order of resistance to heavy metal, in terms of reduction in the cellular population, was Cu2+ > Cd2+ > Cr6+ > Pb2+. Chromium- and cadmium-processing capabilities of the alga were worked out for its potential use as a bioremediator of wastewater. The reduction in the amount of Cr6+ after 2, 4, 6 and 8 days of algal culture containing 5.0 μg Cr6+ ml−1 of culture medium was 77, 85, 92 and 97%, respectively. Distigma could also remove 48% Cd2+after 2 days, 68% after 4 days, 80% after 6 days and 90% after 8 days from the medium. The heavy metal uptake ability of Distigma can be exploited for metal detoxification and environmental clean-up operations.