Poly-γ-glutamic Acid(γ-PGA)를 다량 생산하는 균주를 우리나라의 전통발효식품인 청국장으로부터 Bacillus subtilis GS-2를 분리하였다. 이 균은 glutamic acid 의존형 균으로, 이 균에 의한 γ-PGA 생산 최적 조건을 검토한 바, 단순배 지(L-glutamic acid 2.0%, glucose 1.0%, NH₄Cl 0.5%, KH₂PO₄ 0.05%, MgSO₄, 7H₂O 0.01%, pH 7.0)로 진탕배양(220 rpm) 하였을 때, 배양시간 48시간, 최적온도 33℃, 그리고 초기 pH 6.5로 나타났다. 영양원으로 glutamic acid 3%, sucrose 3%, NH₄Cl 0.25%, KH₂PO₄ 0.15%, MgSO₄, 7H₂O 0.015%에서 γ-PGA 최대 생산량이 31.0 g/ℓ이었다. Key words: Chungkookjang, culture medium, poly(γ-glutamic acid), PGA, soybean paste

A bacterium strain GS-2 isolated from the Korean traditional seasoning food, Chungkookjang and was determined to produce large amounts of γ-PGA with high productivity when provided with simple nutrients (L-glutamic acid 2.0%, glucose 1.0%, NH₄Cl 0.5%, KH₂PO₄ 0.05%, MgSO₄, 7H₂O 0.01%, pH 7.0). In this study, the culture medium for this strain was optimized for the production of γ-PGA. The Bacillus subtilis GS-2 required supplementation with L-glutamic acid and other nutrients for maximal production of γ-PGA. The optimal culture conditions for γ-PGA production were a 48 hr culture time, a temperature of 33℃ and initial pH of 6.5 by rotary shaking (220 rpm). A maximum γ-PGA production of 31.0 g/ℓ was obtained with L-glutamic acid (30 g/ℓ), sucrose (the main carbon source, 30 g/ℓ), NH₄Cl (the main nitrogen source, 2.5 g/ℓ), KH₂PO₄ (1.5 g/ℓ) and MgSO₄, 7H₂O (0.15 g/ℓ) in the culture medium.

• 방병호 | Dong-Heui Yi
• 이문수 | Byung-Ho Bang
• 김관필 | Moon-Soo Rhee
• 이동희 | Kwan-Pil Kim