西藏传统发酵牛乳乳酸菌的鉴定及发酵性能测定

目的研究西藏地区传统的发酵牛乳中乳酸菌的菌属以及其相关性能。方法以西藏拉萨当雄县、那曲比如县、昌都八宿县、山南扎囊县以及日喀则江孜县五个地区采集的传统发酵牛乳为研究对象进行鉴定和性能测试分析。结果分析结果发现其中德氏乳杆菌保加利亚亚种1株，干酪乳杆菌3株，植物乳杆菌1株。通过对分离菌株抑菌性能的测试，发现5株菌都能抑制革兰氏阳性菌，但s012—2菌株对革兰氏阴性菌也有抑制作用。在对菌株产酸、生长速率的测试中发现只有s007—2产酸及生长速率都较慢，几乎不生长。S017—1在8～10h几乎不生长，10～14h产酸和生长较快，其余3个菌株的生长及产酸都在8～16h最快，在16＂~20h处于稳定期。结论通过对西藏不同牧区传统发酵牛乳中分离得到的菌株进行鉴定和发酵性能的测试，对以后设定最优发酵工艺或是将优势菌种应用于食品工业均具有重要意义。

The determination and the fermentability identification of lactic acid bacteria in Tibetan traditional fermented milk

Objective--To research on the musculomyces and the relevant function of lactic acid bacteria in the traditional fermented milk in Tibetan area. Methods--The evaluation and performance test analysis of traditional fermented milk is done which is collected from five counties in Tibet, name- ly, Damxung, Naqu baru, Qamdo Baxiu, Shannan Zhanang and Rigezejiangzi. Results --There is 1 strain of Lactobacillus bulgaricus, 3 strains of Lactobacillus casei and 1 strain of Lactobacillus planta- rum in the traditional fermented milk in Tibetan. By testing the bacteriostatic functions of isolation strains, it was found that s012-2 strain can inhibits Gram-negative bacteria except that all of the five strains can inhibit Gram-positive bacteria. In terms of organic acid produced by bacteria strain and growth rate, it was found that only s007-2 produced organic acid but grew slightly slowly, or even hardly grew. S017-1 hardly grew during 8-16 h but quickly and produced organic acid during 10-14 h. Other three of five bacteria strains grew and produced organic acid quickly during 8- 16 h, steadily during 16-20 h. Conclusion--The test of the determination and fermentability identification of bacteria strain obtained from the traditional fermented milk by isolation is of great significance to setting the best fermentation process or applying the best bacteria strain to food industry.