2.1. Exp. 1
2.1.1. Preparation of starter cultures
Streptococcus thermophiles (CGMCC No. 1.2471) and
Saccharomyces cerevisiae (CGMCC no. 2.1793; Microbial
Institute of the Chinese Academy of Sciences, Beijing,
China) andBacillus subtilisMA139 (National Key Laboratory on Animal Nutrition of China, Beijing, China) were
obtained accordingly.Streptococcus thermophiluswas cultured in de Man, Rogosa and Sharp media at 371C for 24 h.
Saccharomyces cerevisaeandBacillus subtilisMA139 were
grown in yeast peptone dextrose and mixed nutrition
broth in a rotary shaker (225 rpm) at 301C for 24 h,
respectively. After incubation, cells were washed twice
with sterile saline solution and inoculated to have a final
inoculant of 110
7
CFU/mL. The liquid starter culture was
prepared by mixing 3 inoculants before fermentation