FIG. 4.

Effects of supplementation with copper ions on cell viability of BY4741 after freeze-thaw treatment. The cell viabilities after freeze-thaw treatment were measured using YPD (A) and SD (B) agar media containing various copper ion concentrations. The viability of cells before freeze-thaw treatment was relatively set as 100%. The data shown are means of more than triplicate measurements from a representative experiment. Error bars represent the standard deviations of the means. Asterisks and double asterisks indicate that there are significant differences between the viabilities of samples supplemented with no copper and the viabilities of respective samples with P values of <0.05 and <0.01, respectively.