2株猪源乳酸菌对低pH值和胆盐耐受性及热稳定性研究

Survival of Two Lactic Acid Bacteria of Piglet Intestine under Low pH, Bile Salt and Heat Treatment

研究了分离自仔猪肠道的乳酸菌L5和L7对低pH值、胆盐的耐受性。结果表明,pH值在2.5、3.5 和4.5时,L5菌株处理1 50 min对其无显著影响,在pH 1.5时经30 min处理,L5仍可维持较高的存活率;L7菌株在pH 3.5和4.5条件下经150 min处理后可保持较高的存活率,而在pH 1.5和2.5条件下经处理30 min后菌株数量显著下降。胆盐对L5和L7菌株的生长有一定影响,但低浓度短时间内影响较小。在同一胆盐浓度下,随培养时间的增长,活菌数下降。当胆盐浓度高于0.2%时,L5和L7菌株的生长极差。热稳定性试验结果表明,L5菌株在50℃下可成活,且呈正常生长趋势,但其对80℃及以上的耐热能力显著降低。

Effects of low pH, bile salt and heat on the survival of strain L5 and L7 were studied. The results showed that there was no obvious effect on the survival of L5 during 150 minute incubation at pH over 2. 5; and L5 was still able to survive well within 30 minute incubation at pH 1. 5. Strain L7 exhibited a lower acid tolerance than L5, and it was only able to survive at pH 3. 5 and 4. 5. Bile salt affected the growth of the two strain, but the effect was minimal within 1 h incubation with bile salt concentration at 1%. Under the same concentration of bile salt, the bacteria counts decreased as incubation proceeded. When the bile salt concentration was over 2%, the survival count was affected severely. Treatment with 50℃ had no effect on survival of L5,but temperature above 80 'C had significant effect on the survival of L5.