西藏地区牦牛发酵乳制品中乳酸菌的分离与鉴定

Isolation and Identification of Lactic Acid Bacteria from Fermented Yak Milk Products in Tibet Area

实验分析西藏牧民家庭制作的牦牛发酵乳制品中酸奶和奶渣的微生物数量,通过菌种选择分离,采用传统分类与16S rRNA基因序列测定的方法对分离的乳酸菌进行了鉴定。结果表明:3份发酵牦牛乳样品中乳酸菌数为1.04×104～2.10×106CFU/ml,酵母菌数为8.20×103～6.70×105CFU/ml;2份奶渣样品中乳酸菌和酵母菌为0.2×10～1.0×10CFU/g;共分离15株乳酸杆菌、4株乳酸球菌和3株酵母;乳酸菌中10株为Lactobacillus paracasei、1株Lactobacillu fermentum、2株Lactobacillus reuteri、1株Lactobacillus brevis、1株Lactobacillus delbrueckii subsp.bulgaricus、2株Pediococcus acidilactici、另有2株分别为1株Pediococcu和1株Lactococcus菌株,未鉴定到种;L.paracasei为牦牛发酵乳制品中乳酸菌的优势种(占总分离株的55.6%)。

Lactic acid bacteria （LAB） and yeasts involved in production of traditional fermented yak milk products which are made by herdman families in Tibet area, were enumerated and isolated, and the strains of LAB were identified using conventional identification methods and 16S rRNA gene sequence determination method. The results showed that in 3 fermented yak milk, samples, the LAB and yeast counts range from 1.04×10^4 to 2.10 ×10^6 CFU/ml and from 8.20×10^3 to 6.70 ×10^5 CFU/ml, respectively, and in 2 cheese samples, the LAB and yeast counts range from 0.2×10 to 1.0 ×10 CFU/g; 15 Strains of Lactobacillus, 4 stains of lactic acid cocci and 3 stains of yeasts were isolated from fermented yak milk; The LAB species are identified as 10 strains of Lactobacillus paracasei（55.6 % of the total LAB strains ）, 1 strain of LactobaciUufermentum, 2 strains of LactobaciUus reuteri, 1strain of Lactobacillus brevis, 1 strain of Lactobacillus delbrueckii subsp.bulgaricus, 2 strains of Pediococcus acidilactici and 2 strains of Pediococcu and Lactococcus which can not be identified according to the present method.