Influences of culture medium components on the production poly(gamma-glutamic acid) by Bacillus subtilis GS-2 isolated Chungkookjang = 청국장에서 분리한 Bacillus subtilis GS-2에 의한 poly(gamma-gluti\amic acid) 생산의 최적 배양조건

Abstract

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.