对两歧双歧杆菌的4种发酵培养基进行了筛选,确定了适合两歧双歧杆菌BB-G90生长的发酵培养基;研究了5种冻干保护剂对两歧双歧杆菌BB-G90活菌的影响。利用筛选的发酵培养基培养BB-G90,在调控pH=5.0±0.5条件下进行300 L罐中试发酵试验,确定了发酵参数及冻干保护剂配方。试验结果表明:两歧双歧杆菌BB-G90在优化的发酵培养基、适宜的冻干保护剂及调控pH=5.0±0.5条件下发酵终止时间为22 h,此时,发酵液OD600值为5.62,发酵液活菌数为1.80×109CFU/mL,发酵液经离心、乳化及冻干后,菌粉活菌数为4.10×1011 CFU/g。

Mediums and protective agents of Bifidobacterium were screened for maximum viable count,which was the best to obtain maximum viable counts for Bifidobacterium bifidum BB-G90.Growth parameter of B.bifidum BB-G90 were confirmed by fermentation with controlled pH value of 5.0±0.5.Results of the research showed that medium No.3 was the best and the most appropriate protective agent of B.bifidum BB-G90 was No.3.With controlled pH value of 5.0±0.5 the viable cell number of B.bifidum BB-G90 could reach 1.80×109 CFU/mL in the optimal growth medium at 37℃ for 22 h under anaerobic condition.Living bacteria content of B.bifidum BB-G90 powder were 4.10×1011 CFU/g after freeze-drying.