Exploration of β-Glucosidase Activity of Lactic Acid Bacteria Isolated from Kimchi

The ${\beta}$-glucosidase (E.C. 3.2.1.21) production capabilities of lactic acid bacteria isolated from a variety of kimchi (fermented vegetables) were examined. When grown in a medium containing cellobiose as carbon source, most lactic acid bacteria showed significantly higher intracellular levels of ${\beta}$-glucosidase than the extracellular levels. A maximum intracellular ${\beta}$-glucosidase activity of 3.7${\pm}$0.5 (unit/mg protein) was obtained in the case of Weissella cibaria KFRI88010 isolated from kimchi. The optimum reaction conditions for W. cibaria KFRI88010 ${\beta}$-glucosidase activity were pH 5.0 and ${37^{\circ}C}$, and addition of divalent cations to the reaction mixture resulted in a notable decrease in enzyme activity. The ${\beta}$-glucosidase activity was enhanced twofold when W. cibaria KFRI88010 was grown in a medium containing fructose as compared with to a medium containing glucose or cellobiose.

김치에서 분리된 젖산균의 β-glucosidase 활성 탐색

${\beta}$-Glucosidase 효소활성이 높은 균주를 선발하기 위하여 다양한 김치에서 분리된 젖산균의 ${\beta}$-glucosidase 활성을 탐색하였다. 김치에서 분리된 156개의 젖산균 중 134개의 균주만이 cellobiose를 탄소원으로 대사하였으며, 세포내 ${\beta}$-glucosidase 활성이 세포외 활성보다 현저히 높았다. 배추김치에서 분리된 W. cibaria KFRI88010 균주가 3.7${\pm}$0.5 unit/mg protein으로서 가장 높은 세포내 ${\beta}$-glucosidase 효소활성을 나타내었으며, 효소활성은 pH 5, ${37^{\circ}C}$ 반응조건에서 가장 높게 나타났다. $Mn^{2+}$를 비롯한 금속이온은 효소활성을 크게 저해하였다. W. cibaria KFRI88010 균주를 배양할 때 사용한 탄소원 중, fructose는 cellobiose나 glucose와 비교하여 약 2.5배 이상의 높은 세포내 ${\beta}$-glucosidase 효소활성을 나타내었다.