Diversity of lactic acid bacteria and yeasts in traditional sourdoughs collected from western region in Inner Mongolia of China

Twenty-eight traditional sourdough samples for Chinese steamed breads were collected from the western region in Inner Mongolia of China. The values of pH and the total titratable acidity (TTA) of sourdoughs varied from 2.78-5.13 to 8.3-15.5 mL, respectively. In all samples, the number of lactic acid bacteria (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. A total of 108 LABs and 85 yeasts were identified using 16S rRNA gene, 26S rRNA gene sequencing and species-specific PCR. All LAB isolates were identified as 17 species, and all the yeasts were identified as 11 species. Diversity of lactic acid bacteria and yeasts were analyzed by denaturing gradient gel electrophoresis (DGGE). Both the results of identification and DGGE profiles analysis indicated that Lactobacillus plantarum group and Saccharomyces cerevisiae were the predominant microflora in our samples. Further studies by species-specific PCR revealed that all the isolates in Lactobacillus plantarum group were Lactobacillus plantarum. Interestingly, Lactobacillus guizhouensis, Lactobacillus rossiae, Rhodotorula mucilaginosa and Pichia farinosa isolated by cultured-based method were not detected by DGGE, whereas Lactobacillus zeae was only found in DGGE profiles.