Viili中益生菌的分离及其发酵性质研究

目的 利用传统方法和分子生物学方法从viili中筛菌并对其特性进行研究.方法 采用MRS、YPD和脱脂乳营养琼脂3种平板从viili中分离出15株单菌,利用V3区通用引物和乳杆菌特异性引物对各单菌的PCR产物进行变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)分析,将其归为5种不同菌.结果 16S DNA测序表明,5种单菌分别为Lactobacillus plantarum、Streptococcus thermophilus、Lactobacillus paracasei、Bacillus cereus和Lactobacillus delbrueckii subsp. bulgaricus.混合发酵实验表明:从viili中筛出的5种菌除Bacillus cereus外均有凝乳现象,其中Lactobacillus delbrueckii凝乳能力强,可在5 h内凝乳;Lactobacillus paracasei、Bacillus cereus和Lactobacillus plantarum组合产生的EPS量最多,高达186.71 mg/L,而Streptococcus thermophilus EPS产量仅为33.56 mg/L.结论 传统方法与分子生物学方法DGGE相结合,可以快速准确判断细菌种类;筛选菌特性研究结果表明,细菌之间的相互作用导致凝乳时间和EPS产量发生变化,其复合作用有待于进一步研究.

Study on the isolation and fermentation of probiotics in Viili

15 strains were isolated from viili by incubation in MRS, YPD and skimmed milk plates, and grouped into 5 different species by using DGGE method. The sequencing results of 16S DNA showed that they belonged to Lactobacillus plantarum, Streptococcus thermophilus, Lactobacillus paracasei, Bacillus cereus and Lactobacillus delbrueckii subsp. Bulgaricus, respectively. Mixture fermentation experiments showed all the strains (except Bacillus cereus) possessed curding capabilities, thereof Lactobacillus delbrueckii presented the stongest curding capability in 5 h; group of Lactobacillus paracasei+Bacillus cereus+Lactobacillus plantarum produced the highest yields of EPS as high as 186.71 mg/L, on the other hand Streptococcus thermophilus produced EPS only at 33.56 mg/L. Our results indicated that interaction among isolates from villi resulted in the changing of curding time and EPS yields, and need further researching.