Isolation and Characterization of Antifungal Compounds Produced by Bacillus polyfermenticus CJ6 Isolated from Meju

Antifungal compounds from Bacillus polyfermenticus CJ6 were purified using SPE, preparative HPLC, and reverse phase-HPLC. Antifungal compounds from B. polyfermenticus CJ6 were separated into three fractions (8, B, C) using preparative HPLC. LC/MS analysis of antifungal peaks suggested that B. polyfermenticus CJ6 produces lipopeptides; two kinds of iturin A ($C_{14}$, $C_{15}$), three kinds of surfactins ($C_{13}$, $C_{14}$, $C_{15}$), four kinds of fengycin A ($C_{14}$, $C_{15}$, $C_{16}$, $C_{17}$) and two kinds fengycin B ($C_{16}$, $C_{17}$). The antifungal activity of fraction 8, which was presumed as inturin A, was found to be stable after the pH, heat or proteolytic enzyme treatment, but it was unstable at 50-$70^{\circ}C$ for 24 hr. The antifungal activity of fraction B, which presumed as surfactins and fengycin A, was found to be stable after the heat treatment, but it was unstable in the pH 3.0 and after the protease (type I) or ${\alpha}$-chymotrypsin treatment. The antifungal activity of fraction C, which was presumed as fengycin A and B, was found to be stable in the pH 3.0-9.0 range and the heat treatment, but it was unstable with the treatment of protease (type I). The amino acid composition of the purified peaks 8-1 and 8-2 were Asx, Tyr, Gln, Pro, and Ser in a molar ratio of 3:1:1:1:1, which showed the same amino acid composition as iturin. From these results, we confirmed that antifungal compounds from B. polyfermenticus CJ6 most likely belonged to iturin A as well as surfactins and fengycins. As lipopeptides are known to act in a synergistic manner, the antifungal compounds from B. polyfermenticus CJ6 might have potential uses in biotechnology and biopharmaceutical applications.

메주에서 분리한 Bacillus polyfermenticus CJ6가 생산하는 항진균 물질의 분리 및 특성

B. polyfermenticus CJ6가 생산하는 항진균 물질을 분리 정제하기 위하여 SPE, preparative HPLC, reverse phase-HPLC를 통한 정제를 시행하였다. Preparative HPLC로부터8, B, C의 3개의 항진균 활성 분획을 분리하였으며, LC/MS분석 결과 B. polyfermenticus CJ6는 2종의 iturin A($C_{14}$, $C_{15}$), 3종의 surfactin($C_{13}$, $C_{14}$, $C_{15}$), 4종의 fengycin A($C_{14}$, $C_{15}$, $C_{16}$, $C_{17}$)와 2종의 fengycin B($C_{16}$, $C_{17}$)를 생산하는 것으로 추정되었다. 분리된 항진균 활성 분획의 안정성 실험을 결과 iturin을 함유한 8번 분획은 pH, 열, 효소처리에 안정하였으나 50-$70^{\circ}C$에서 24시간 처리 시에는 항진균 활성이 다소 감소되었다. Surfactins과 fengycins을 포함하는 것으로 추정되는 B 분획은 온도에는 매우 안정하나 pH 3.0과 protease(type I) 및 ${\alpha}$-chymotrypsin 처리에 의하여 항진균활성이 감소되었다. Fengycins 만을 함유한 C 분획은 열과 pH 처리에서 모두 안정하였으나 protease(type I) 처리에 의하여 활성이 감소되었다. 항진균 활성 8번 분획은 reversephase-HPLC를 통하여 2개의 단일 피크가 분리되었으며, 아미노산 조성 분석 결과 Asx, Tyr, Gln, Pro, Ser의 분자비가 3:1:1:1:1으로서 iturin A의 아미노산 서열과 일치하는 것으로 확인되었다. 본 연구를 통하여 B. polyfermenticus CJ6는다양한 항진균 활성 lipopeptides를 생산하는 것을 알 수 있으며, 항진균 활성이 우수한 B. polyfermenticus CJ6 균주의 생물방제 및 생물보존제로서의 활용이 기대된다.