保加利亚乳杆菌H+-ATPase缺陷型菌株延缓后酸化及发酵性质的研究

检测由新霉素筛选保加利亚乳杆菌L15-4后酸化程度,并通过正交试验确定目的菌株的最适高密度发酵培养基组成.3株保加利亚乳杆菌(L15-4、L15、LW-1),42℃发酵酸奶,酸奶分别在4和20℃储存检测pH和滴定酸度变化;3株保加利亚乳杆菌分别与嗜热链球菌S18混合42 ℃发酵酸奶,酸奶分别在4和20 ℃储存检测pH和...

Study on H+-ATPase deficient mutant of Lactobacillus delbrueckii subsp.bulgaricus to post-pone postacidification of yogurt and property of fermentation

The post-acid level of Lactobacillus delbrueckii subsp. bulgaricus named L15-4 was examin-ed,which was selected by neomycin,and the components of the optimal high density fermentation medium for the strains were studied by orthogonal test. The yogurt fermented by three Lactobacillus delbrueckii subsp. bulgaricus on 42 ℃ examined the change of the pH and titratable acidity,when the yogurt were stored at 4 and 20 ℃. And the yogurt fermented by 3 Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus the-rmophilus on 42 ℃ examined the change of the pH and titratable acidity,when the yogurt were stored at 4 and 20 ℃. MRS medium was the basic medium for the slected stains,potato juice,skim milk and yeast extract were screened for the selected strains. The result showed that the post-acid level of L15-4 was weaker than that of L15 and LW-1;and most optimum enrichment mediums was 3.0% skim milk,5.0% potato juice,and 0.5% yeast extract.