Characterization of Saccharomyces cerevisiae mutants resistant to high concentrations of Co2+: A primary step to bioremediation by removal and recovery of Co2+ from waste waters

Abstract

Engineering cell lines that hyperaccumulate heavy metals can be an invaluable tool in removing such ions from aqueous environments. In this study we obtained Saccharomyces cerevisiae mutants that were tolerant to high concentrations of Co2+. Chemically mutagenized yeast cells were plated on media containing lethal doses of Co2+. Five resistant colonies were isolated and characterized in terms of Co2+ tolerance and cation accumulation. Four mutants gained the Co2+-tolerance due to low level of accumulation, and only one mutant had the capacity to hyperaccumulate Co2+. Monitoring the intracellular distribution of Co2+ in the hyperaccumulating mutant revealed that the cation was mainly compartmentalized within the vacuoles. Utilizing hyperaccumulating mutants may facilitate the rational design of strategies for bioremediation of heavy metal waste waters.