Copper tolerance in Saccharomyces cerevisiae

Abstract

A commercial strain of Saccharomyces cerevisiae was serially cultured in media containing copper up to a final concentration of 10 mmol l‐1. This copper‐tolerant subculture was assessed for its capacity to accumulate further quantities of copper. It was found that after Cu2+ accumulation the total copper content of this yeast was lower than the parent culture when exposed to similar conditions, indicating that the subculture was copper‐resistant owing to reduced copper bioaccumulation properties. Although a low mass copper binding compound was isolated from the copper‐tolerant subculture, no metallothionein was found. Scanning electron microscopy of S. cerevisiae showed the cell surface to be smooth except for bud scars. After exposure to copper ion‐containing solutions the surface of copper‐tolerant yeast became convoluted, the cell was generally more spherical and somewhat smaller.