BIOREMEDIATION OF SOIL BY REMOVING HEAVY METALS USING Saccharomyces cerevisiae

Heavy-metal pollution represents an important environmental problem due to the toxic effects of metals, and their invasion in to the food chain leads to serious ecological and health problems. Metal remediation through common physico-chemical techniques is expensive and unsuitable in treating large contaminated area effectively. Bioremediation offers a promising means to reclaim such contaminated soil in an economical and eco friendly way. Bioremediation employs microorganisms capable of degrading toxic contaminants or have the ability to accumulate it in their cells. This concentrated end product can afterwards be directed for a controlled way for recovery of metals. In this study Saccharomyces cerevisiae was used for the removal of heavy metals like Lead and Cadmium from contaminated soil. The tolerance of Saccharomyces cerevisiae against the metals was found to be upto 250 ppm and for Pb2+, 500 ppm for Cd2+. The parameters affecting the biosorption of heavy metals;. such as time, metal concentration and biomass concentrations have been investigated. The results revealed that biosorption of about 67-82% of Pd2+ and 73-79 % of Cd2+ was attained within 30 days. The time taken for maximum sorption of Pb2+ and Cd2+ was 30 days for soil containing 100 and 300 ppm of Pb2+ and Cd2+ respectively. Biosorption rate are higher when the cells are in stationary phase. The biosorption and the growth of the microorganism in aerated soil were found to be more comparing to non-aerated soil.