Uptake of heavy metals by Stylonychia mytilus and its possible use in decontamination of industrial wastewater

Abstract

The heavy metal resistant ciliate, Stylonychia mytilus, isolated from industrial wastewater has been shown to be potential bioremediator of contaminated wastewater. The ciliate showed tolerance against Zn2+ (30 μg/mL), Hg2+ (16 μg/mL) and Ni2+ (16 μg/mL). The metal ions slowed down the growth of the ciliate as compared with the culture grown without metal stress. The reduction in cell population was 46% for Cd2+, 38% for Hg2+, 23% for Zn2+, 39% for Cu2+ and 51% for Ni2+ after 8 days of metal stress. S. mytilus reduced 91% of Cd2+, 90% of Hg2+ and 98% of Zn2+ from the medium after 96 h of incubation in a culture medium containing 10 μg/mL of the respective metal ions. Besides this, the ciliate could also remove 88% of Cu2+ and 73% Ni2+ from the medium containing 5 μg/mL of each metal after 96 h. The ability of Stylonychia to take up variety of heavy metals from the medium could be exploited for metal detoxification and environmental clean-up operations.