Rhodotorula mucilaginosa isolated from the manganese mine water in Minas Gerais, Brazil : potential employment for bioremediation of contaminated water.

Abstract

Manganese (Mn) is an essential heavy metal for living organisms. However, they tend to accumulate the excess of this element causing health problems. The increase of the environmental contamination by this heavy metalis mainly due to mining practices. This work aimed to isolate yeast from mining waters to evaluate its ability of removing Mn2+ ions for the development of further biotechnological and bioremediation applications. The growing interest of this study is because it could be effective in the biological treatment of contaminated water, which remains a major challenge for industry and environment. Yeasts were initially isolated from mining water and grown in YPD medium containing 1 to 54 mM Mn2+. Subsequently, the isolates were characterized biochemically and phylogenetically. Then, we evaluate the ability of the isolates of removing Mn2+ ion by SEM scanning electron microscopy coupled with SEM/EDX. Our results showed yeast growth up to 32 mM. There was no pH increase along the tests, suggesting a biological Mn2+ removal. Taken together, the morphological changes in the colony and the darkening of the culture medium suggest the yeast’s ability of oxidizing Mn2+. Five isolates remove these ions considerably, identified as Rhodotorula mucilaginosa. SEM/EDX analysis shows the ability to oxidize and adsorb Mn. The data obtained in this work allows us to conclude that R. mucilaginosa has an important role in the biogeochemical cycle of manganese and present potential biotechnological applications for bioremediation of water contaminated with Mn2+ ions.