Strains A and B were cultured in 400 ml MSM medium at 28 C,
shaking at 120 r/m to the OD600 maximum (OD600 was approximately
2.1). After this, the yeast mycelium were collected by centrifuge,
re-suspended in a sterile phosphate buffer, and sterilized at
a high temperature for a short time to death. This solution was
then diluted with different concentration of Cu2+ (as fermentation
experiments) and sterile phosphate buffer to 400 ml, and shaken at
28 C and 120 r/m. Samples were collected regularly and stored in
40 C before testing.