Rhodotorula glutinis NRRL-Y-1091, a red oleaginous yeast, was grown in batch and continuous culture system.
At batch culture, the accumulaion of lipid is favoured not only by nitrogen limitation but also by deficiency in magnesium and phosphate. It would appear from the above observations that any constraint which limits growth but not assimilation of the carbon source will tend to cause accumulation of lipid.
At continuous culture, mass and energy balance method was used to analyze that the cell concentration decreased rapidly with increasing dilution rate. Energetic yield, η, decreased with increasing dilution rate, but metabolic heat fraction, ε, increased with increasing dilution rate. Since η + ε, is almost constant at all dilution rate experimented, it may be said that product formation may not be correlated with that result. Since in experiment, the dissolved oxygen concentration was maintained at 50% at higher dilution rate, incomplete aeration and agitation were not correlated with that result.
The medium may be inadequate in composition and preparation procedure. Therefore, medium optimization in continuous culture was carried out using a pulse method.
연속식 배양에서 유지 생산균인$\underline{R}$.$\underline{glutinis}$ 의 균체량을 증가시키기 위해 pulse method를 이용 배지 재조성 실험을 행하였다.
회분식 배양 실험 결과, 질소원 (지질 함량 47% wt/wt 외에 magnesium (30% wt/wt)을 제한했을 때와 phosphate (35% wt/wt) 를 제한했을 때도 상당한 량의 지질을 축적하였고 질소원을 제한하였을때 균체량과 지질 함량이 가장 높았다.
질소원 제한 조건하에서 연속식 배양 실험 결과, 희석율이 증가할수록 생체량 및 지방 함량은 급격히 감소하였다. Mass and energy balance 분석을 한 결과 열역학적 균체 수율 (energetic yield, n )과 대사열 비율 (metabolic heat fraction)의 합이 평균 0.966, 표준편차 0.0387 로 희석율에 관계없이 거의 일정한 값을 가졌다. 희석율이 증가할수록 균체량이 감소하는 것은 product 형성과 관계가 없음을 확인할 수 있었다.
기존 질소원 제한 배지에 철 ($FeSO_4$·$7H_2O$ 3 mg/ℓ) 망간 ($MnSO_4$·$45H_2O$ 100 ㎍/ℓ), grwth factor (biotin 20 ㎍/ℓ, pantothenic acid (200 ㎍/ℓ), 구리 ($CuSO_4$·$5H_2O$ 100 ㎍/ℓ)첨가함으로써 균체량을 OD = 6 에서 OD = 17까지 증가시킬 수 있었다.