Culture media containing different concentrations of lactose were prepared by dissolving dried whey permeate powder in distilled water, adding commercial agar (Becton Dickinson and Co., Sparks, MD) in the ratio of 1.5% (wt/vol), mixing, and autoclaving (120°C, 20 min). The pH was adjusted as required using 0.5 M NaOH or 0.5 M HCl. Media were poured into Petri dishes and allowed to solidify. Because the purpose of this research was to provide information about the treatment of raw cheese whey permeate as a growth substrate for mushroom mycelia, no other nutrients were added.