젖산 발효제품에서 분리한 유산균의 내산성 비교

Comparative Tests on the Acid Tolerance of Some Lactic-Acid-Bacteria Species Isolated from Lactic Fermented Products

유제품 30여종과 야채발효 제품 2종에서 Lactobacillus casei ssp.(5 strains), Lactobacillus acidophilus(2 strains), Lactobacillus delbrueckii ssp. bulgaricus(6 strains), Lactobacillus plantarum(3 strains), Streptococcus salivarius ssp. thermophilus(11 strains), and Streptococcus faecalis(2 strains)를 각각 분리하여 이들의 내산성과 담즙산 내성을 평가하였다. 초기생균수를 고려하여 공분산분석으로 내산성을 비교한 결과, L. casei에 속하는 균주들의 내산성이 가장 우수하였으며, L. bulgaricus와 균주들은 가장 낮은 내산성을 보였다(p<0.05). 담즙산 내성은 L. casei, L. plantarum, L. acidophilus, S. feacalis 균주들의 경우 비슷한 경향을 보였으나, L. bulgaridus와 S. thermophilus 그룹에 속하는 균주들의 담즙산 내성은 거의 없는 것으로 나타났다.

We isolated sixty lactic acid bacteria(LAB) from lactic fermented products. Among 60 isolates of LAB, 30 isolates were identified as Lactobacillus casei ssp.(5 strains), Lactobacillus acidophilus(2 strains), Lactobacillus delbrueckii ssp. bulgaricus(6 strains), Lactobacillus plantarum(4 strains), Streptococcus salivarius ssp. thermophilus(11 strains), and Streptococcus faecalis(2 strains). The acid tolerance and bile resistance of 30 LAB were determined. Because the acid tolerance was affected by the initial cell concentrations, the analysis of covariance could be used to remove the effect of initial cells on acid tolerance when testing for differences in acid tolerance among six species. Viability of LAB under acidic condition, pH 3 for 2 hours at $37^{\circ}C$, was significantly different among the species. L. casei and L. acidophilus strains showed great viability, but L. bulgaricus and S. thermophilus strains were very weak in acid tolerance.