Copper resistance and accumulation in the zygomycete Mucor rouxii

Two copper-resistant (Cop(r)) mutants, strains P1 and P3, were obtained from the dimorphic fungus Mucor rouxii. They were characterized as to their ability to take up copper in a growth medium supplemented with this metal ion. Detection of copper by linear sweep striping voltammetry in cell walls and in the cell wall-free fraction of disrupted cells revealed a higher content of the metal in both mutant fractions, as compared with those of the copper-sensitive (Cop(s)) parental strain. Copper binding by M. rouxii growing cells was also studied through the use of a cytochemical method based on the compounds neocuproine (NCP) and sodium diethyldithiocarbamate (DTC). This method indicated that the P1 Cop(r) strain accumulated more metal than the parental Cop(s) strain, both on the cellular surface and in the intracellular milieu.