Characterization of Bacteriocin, lacticin YH-10, Produced by Lactococcus lactis subsp. lactis YH-10 Isolated from Kimchi

A bacteriocin-producing lactic acid bacteria was isolated from Kimchi on MRS selective media with the use of Lactobacillus delbrueckii subsp. delbrueckii as an indicator strain. The strain YH-10 was identified as Lactococcus lactis subsp. lactis through the API test. The crude bacteriocin (freeze-dried 50% ammonium sulfate precipitate of culture supernatant) produced by the strain was named as lacticin YH-10. Lacticin YH-10 showed the growth inhibitory activity against Gram positive pathogenic bacteria and other lactic acid bacteria. The bacteriocin was inactivated by proteases such as protamex and aroase AP-10 and partially inactivated by amylase, proteinase K, trypsin, and papain. The lacticin YH-10 remained its activity with the treatment of heat at 10$0^{\circ}C$ for 60 min or the changes of pH 2 to 11. However, the activity was lost at high pH combined with the exposure to 10$0^{\circ}C$. The bacteriocin production of the strain was started in the exponential phase and stopped in the stationary phase. The approximate molecular mass of the bacteriocin produced by the strain was approximate 14 kDa in the analysis on SDS-PAGE.

김치유산균인 Lactococcus lactis subsp. lactis YH-10가 생산하는 박테리오신의 특성

API test를 통해서 김치에서 분리한 유산균이 Lactococcus lactis subsp. lactis의 한 종임 을 확인하고 Lactococcus lactis subsp. lactis YH-10이라 명명하고, 생산된 박테리오신을 lacticin YH-10으로 명명하였다. Lactococcus lactis subsp. lactis YH-10을 $25^{\circ}C$, 3$0^{\circ}C$와 37$^{\circ}C$에서 배양한 결과 $25^{\circ}C$에서 박테리오신을 생성하였다. Lacticin YH-10은 여러 가지 단백질 분해효소에 의해 항균활성을 소실하였으므로, 단백질로된 박테리오신임을 확인하였다. 또한 $\alpha$-amylase, $\beta$-amylase, glucoamylase의 처리에도 활성을 일부 소실하였으므로 박테리오신의 분류 중 classIV에 속함을 알 수 있었다 Ammonium sulfate정제한 후 SDS-PAGE를 통해 박테리오신의 분자량이 대략 14kDa임이 확인되었다. Lacticin YH-10은 단백질계 물질로서 인체 내에서 분해가 가능하기 때문에 일반 화학 보존제 보다 인체에 안정함을 알 수 있다. Lacticin YH-10은 낮은 pH와 높은 온도에서 항균활성을 가지고 있기 때문에 식품보존제로서 이용할 수 있다.