Biomineralization in Candida fukuyamaensis rcl-3 under copper overload

Abstract

Copper (Cu) plays an essential role in cellular metabolism due to its versatility as a biological catalyst. It is required as a catalytic cofactor in many enzymes involved in diverse cellular processes. While trace amounts of copper are essential for life, coppercan easily react with oxygen or hydrogen peroxide (H2O2) generating reactive oxygen species (ROS) that may damage cell constituents through the oxidation of proteins, cleavage of DNA and RNA, and lipid peroxidation. Candida fukuyamaensis RCL-3 (NCBI number AY743221), yeast strain isolated from a copper filter plant at the province of Tucumán, Argentina, has the abilityof supporting high amounts of copper metal by a slowdown in its growth rate. Bioremediation mechanisms as bioaccumulation, biospeciation, biomineralization has been descripting in yeast. In order to understand the mechanism involved in C. fukuyamaensis RCL-3 resistance to copper it was conducted an approach. Atomic absorption spectroscopy results showeddecrease copper concentration (from 0.5 to 0.14 ± 0.05 mM) in the culture medium after 16 h inoculation. At the same time, change in cells coloration to brownish color was observed. Is known that cooper sulfide (CuS) mineralization on the surface of cells causes the cells turns brown. Upon addition of KCN to Cu-grown C. fukuyamaensis RCL-3 cells, the brownish colorationwas bleached instantly, and cooper ions were solubilized. Sulfate reduction as the brown coloration of Cu-treated cells was attenuated when ammonium chloride was substituted for ammonium sulfate in the growth media.