In solid state culture, one unit of cutter square (5 mm × 5 mm, prepared by a self-designed cutter) of the activated P. eryngii mycelium was inoculated into MHP agar plate (containing 1.5% MHP and 2.0% agar, with pH adjusted to 5.80 using 1 N HCl) at 25 8C for 7 days.