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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16SDNA测序表明,5种单菌分别为Lactobacillus plantarum、Streptococcus thermophilus、Lactobacillus paracasei、Bacillus cere-us和Lactobacillus delbrueckiisubsp.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Lactoba-cillus plantarum组合产生的EPS量最多,高达186.71 mg/L,而Streptococcus thermophilusEPS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。
Objective To screen the bacteria from viili by traditional methods and molecular biology and to study its characteristics. Methods 15 strains of single bacteria were isolated from viili by using MRS, YPD and skim milk nutrient agar plates. Denaturing gradient gel electrophoresis (PCR) was carried out on the PCR products of each of the three strains using V3 region universal primers and Lactobacillus specific primers gel electrophoresis, DGGE) analysis, which is classified as five different bacteria. Results 16SDNA sequencing showed that the five species were Lactobacillus plantarum, Streptococcus thermophilus, Lactobacillus paracasei, Bacillus cereus and Lactobacillus delbrueckiisubsp. Bulgaricus respectively. The mixed fermentation experiments showed that the five kinds of bacteria screened out from viili were all curd except Bacillus cereus, among which Lactobacillus delbrueckii was capable of curdling within 5 h. Lactobacillus paracasei, Bacillus cereus and Lactoba-cillus plantarum The combination produced the highest amount of EPS, up to 186.71 mg / L, while Streptococcus thermophilus EPS production was only 33.56 mg / L. Conclusion The traditional method combined with molecular biology method DGGE can rapidly and accurately determine the bacterial species. The results of screening bacteria showed that the interaction between bacteria led to the change of curd time and EPS yield, and its complex role needs to be further studied.