Co2+ and Ni2+ resistance in Saccharomyces cerevisiae associated with a reduction in the accumulation of Mg2+.

A mutant strain of Saccharomyces cerevisiae (NR 6), which can be associated with a reduction in the accumulation of Mg2+ has been isolated. This mutant strain displays resistance to both Ni2+ and Co2+, but not, however, towards Cu2+, Cd2+, Mn2+, Zn2+ and Cr2O7(2-). Both Co2+ and Ni2+ uptake by the mutant strain is less than by the wild type (CMR-50). The inhibitory effects of Ni2+ and Co2+ on the growth of both strains NR-6 and CMR-50 can be cancelled by increasing the concentrations of Mg2+ in the medium and to a lower extent by the addition of Ca2+ which results in a decreased uptake of these metals. It therefore appears that the resistant mechanisms of this mutant strain NR-6 is due to a reduction in the uptake of Co2+ and Ni2+ via a Mg2+ transport system.