西藏地区藏北嵩草附着乳酸茵的理化特性

本研究以藏北嵩草（Kobresia littledalei）上附着的乳酸菌为研究对象,分离得到肠膜明串珠菌肠膜亚种两株,融合魏斯氏菌11株,食物魏斯氏菌6株,然后对这3种试验菌进行不同温度及pH条件下的生长试验、耐盐试验及糖发酵试验等生理生化特性的研究。结果表明,与常规条件下分离得到的相同菌株相比较,青藏高原极端环境中分离的魏斯氏乳酸菌和明串珠菌株都能在4~40 ℃的条件下生长,部分融合魏斯氏菌还可在50 ℃下微弱生长;耐酸碱试验表明,魏斯氏乳酸菌株都能在pH值为3.0和9.5的条件下生长;在耐盐性方面,部分魏斯氏菌可以在18%的NaCl下生长;在碳源利用方面,本研究提取的食物魏斯氏菌可利用半乳糖;融合魏斯氏菌可利用阿拉伯糖、蜜二糖、甘露醇。因此,藏北嵩草中所分离的乳酸菌比常规环境中的乳酸菌有较强的耐温性和耐酸碱性,而且能更广地利用碳源,从而为其在饲料青贮、酸奶发酵等方面的应用奠定基础。

Physiological and biochemical characteristics of lactic acid bacteria isolated from Kobresia littledalei in Tibet

Two strains of Leuconostoc mesenteroides subsp. Mesenteroides, 11 strains of Weissella confusa and 6 strains of W. cibaria were isolated from Kobresia littledalei growing on the Tibetan Platea. The physiological and biochemical characteristics of these epiphytic lactic acid bacteria were analyzed in this study. The results of sugar fermentation patterns and salt, temperature and pH tolerance test showed that, compared with the same species strains isolated from conventional conditions, the Weissella and Leuconostoc strains could be cultured at 4～40 ℃, and a part of W. confusa strains could grow weekly at 50 ℃; Weissella strains could grow when the pH values were 3.0 and 9.5; Weissella strains could grow when the concentration of NaCl is 18%; the strains isolated from W. cibaria could ferment galactose, and strains isolated from W. confusa could ferment arabinose, melibiose andmannitol. Therefore, the lactic acid bacteria isolated from K. littledalei not only have stronger temperature, acid and alkali resistance, but also can ferment more carbohydrates than that of strains isolated under conventional conditions. The results of this study can provide scientific basis for researches on diversity of lactic acid bacteria in Qinghai Tibet Plateau and their application in silage.