【摘要】 采用响应面法对保加利亚乳杆菌(Lactobacillusbulgaricus)和嗜热链球菌的增菌(Streptococcusther-mophilus)培养基进行了优化,并且对其冻干保护剂进行了筛选,结果表明通过流加碱控制保加利亚乳杆菌的pH值为5.8,嗜热链球菌的pH值为6.4,培养15h,菌体的浓度分别达到1.24×109cfu/mL和8.05×108cfu/mL。离心收集到的菌体,在-70℃的冰箱先预冻3h,然后在冷阱温度-51℃、真空度9Pa冻24h,最终可以得到含活菌数为1.43×1010cfu/g的高活力酸乳发酵剂。更多还原

【Abstract】 Response surface methodology was used to optimize the MRS-based culture medium for Lactobacillus bulgaricus and Streptococcus thermophilus culturing, also the best freezing-dried protectors were studied. The experiment shows that Na2CO3 solution was added continuously to keep lactobacillus bulgaricus pH around 5.8, streptococcus thermophilus pH around 6.4. By fermentation with 15h, the lactobacillus bulgaricus concentration can reach 1.24×109cfu/mL and Streptococuus thermophilus with 8.05×108cfu/mL. The collected bacteria by centrifugal separation was freezing-dried at -51℃, vaccum value 9Pa, 24h, at last the living bacteria amount can reach 1.43×1010cfu/g.更多还原