The suspension was placed into
sterile tubes and centrifuged at 4000 ×g for 20 min and the supernatants
were discarded. The remaining spores in pellets were washed twice with
sterile distilled water, and the final suspension was stored at −20 °C
until use. Sterile distilled water was used to standardize the concentration
of spores in the suspension at 106 spores/mL. The concentration of
spores was verified through enumeration with YSG agar (pH 3.7 ± 0.1)
after heat shock at 80 °C for 10 min