Materials and methods
2.1. Microorganism and spawn preparation
Pleurotus ostreatus, obtained from the Mushroom Spawn Research
Center of Huazhong Agricultural University (Wuhan
City, Hubei, China), was grown on the potato dextrose agar
(PDA 200 g/l diced potatoes; 20 g/l glucose; 15 g/l agar) medium
at 25 C for regular subculture. Oyster mushroom spawn
was prepared in 850-ml polypropylene plastic bottles filled
with cotton seed hull 87%, wheat bran 10%, sucrose 1%, plaster
stone 1%, and calcium superphosphate 1% (w/w, in terms
of dry weight), which were widely used in central China, and
then autoclave sterilized at 121 C for 80 min. After cooling
down to room temperature, the sterilized cotton seed hulls of
every bottle were inoculated with 5 cm2 mycelial agar discs.
The spawn was incubated in the laboratory at 26 ±2 C and
70% relative humidity for two weeks.