传统发酵牦牛酸乳中高产胞外多糖乳酸菌的筛选与鉴定

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

目的：以四川红原、西藏羊八井地区传统牦牛酸乳中分离出的57株乳酸菌作为实验菌种，筛选出高产胞外多糖乳酸菌。方法：通过菌落拉丝法、硫酸-苯酚法的测定。结果：实验菌株胞外多糖产量在19．95～91．08μg／mL之间，其中菌株代号为32-2、67-1、41-1和27的胞外多糖产量较高，分别为91．08、89．76、87．22、87．40μg／mL。通过16SrDNA序列同源性鉴定表明代号32—2菌株鉴定为屎肠球菌（Enterococcusfaecium）、代号67-1菌株为肠膜明串株菌肠膜亚种（Leuconostocmesenteroidessubsp．mesenteroides）、代号41—1菌株为干酪乳杆菌（Lactobacilluscasei）、代号27菌株为肠膜明串珠菌（Leueonostocmesenteroides）。结论：为研究具有提高酸乳品质能力的发酵菌株提供依据。

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 2,2-2,67- 1,41 -1 and 27, possessed the high exopolysaccharide- producing and the production was 91.08、89.76、87.22、87.40μg/mL respectively.Based on 16S rDNA sequence analysis, 32-2 was identified as Enterococcus faecium, 41- 1 as Lactobacillus casei,67-1 as Leuconostoc mesenteroicles subsp, mesenteroides,27 as Leuconostoc mesenteroides. Conclutions This study could provide the evidence for researching fermentation strains to improve yogurt quality.