Identification And Biodiversity Of Yeast And LAB Isolated From Sourdoughs Collected From Western Region Of Inner Mongolia

The yeast and lactic acid bacteria(LAB)in sourdoughs collected from west of Inner Mongolia were isolated and identified, after that the diversity of yeast and lactic acid bacteria were analyzed by culture-dependent method and denaturing gradient gel electrophoresis (DGGE). The results of this research would be more helpful in protecting and further utilization of abundant microflora in sourdoughs.The values of pH and the total titratable acidity (TA) of sourdoughs collected from seven region of Inner Mongolia varied from 2.78-5.13 to 8.3-15.5 mL, respectively. In all samples, the number of LAB ranged from 6.56 to 8.72 Log cfu/g, while the amount of yeasts ranged from 4.13 to 6.37 Log cfu/g, generally, the counts of LAB were higher than those of the yeast by one o two logarithms.A total of 85 strains of yeast were isolated from twenty eight sourdough samples, and identified by 26S rDNA D1/D2 domain sequencing method. The result was including S.cerevisiae for forty-three strains(50.59%), C.humilis for twenty-two strains(25.88%), T.delbrueckii for six strains, P.anomala for three strains, K.exigua for two strains, P.kudriavzevii for two strains, C.parapsilosis for two strains, L.elongisporus for two strains, P.farinose for one strain, P.guilliermondii were one srain, Rh.mucilaginosa for one strain;One hundred and eight strains of LAB were isolated and identified by 16S rDNA sequencing method, The result was including L.plantarum for thirty-seven strains(33.94%), Le. citreum for fourteen strains(12.84%), W. cibaria for ten strains, L. paralimentarius for eight strains, W. confuse for seven strains, L. helveticus for seven strains, L. mindensis for four strains, Lactococcus lactis subsp. lactis for three strains, L. curvatus for three strains, L. rossiae for three strains, L. mesenteroides for two strains, L. brevis for two strains, L. guizhouensis for two strains, L. sanfranciscensis for two strains, L. crustorum for two strains, L. fermentum for 1 strain, E. durans for one strain.Biodiversity of yeast and LAB in sourdough samples were analyzed combining with 16S/26S rDNA gene sequences and PCR-DGGE technology. The result indicated that S.cerevisiae, L. plantarum and L. sanfranciscensis were the predominant microflora in these samples. There was great difference between culture-dependent method and PCR-DGGE method in microbial diversity research: The former would be influenced by subjective factors from operator, and some species of yeast or LAB were lost;the latter had deviation caused by limit of detection and dead cells in samples, consequently, combining with these two methods could get accurate and comprehensive description of biodiversity of sourdoughs collected from west region of Inner Mongolia.