Screening and identification of lactic acid bacteria strains with high exopolysaccharide- producing from traditional fermented Yak Yogurt

Objective: Screening lactic acid bacteria( LAB) with high exopolysaccharides from 57 strains of lactic acid bacteria,which were isolated and purified from traditional fermented Yak Yogurt in Hongyuan- Sichuan and Yangbajing- Tibet. Methods: The strains with high exopolysaccharides( EPS) were screened by colony thread-drawing method and phenol- sulfuric acid method. Results: The four strains,screening number 32- 2,67- 1,41- 1and 27,possessed the high exopolysaccharide- producing and the production was 91.08,89.76,87.22,87.40 μg / m L respectively.Based on 16 S r DNA sequence analysis,32- 2 was identified as Enterococcus faecium,41- 1 as Lactobacillus casei,67-1 as Leuconostoc mesenteroides subsp.mesenteroides,27 as Leuconostoc mesenteroides.Conclutions: This study could provide the evidence for researching fermentation strains to improve yogurt quality.