For the high production of carboxymethyl cellulase (EC 3.2.1.4) by a recombinant cell, Bacillus megaterium pCK108, exponential feeding fed-batch culture for high density cell cultivation was carried out. In the culture system, specific growth rate, could be controlled by manipulating a feed rate of fresh medium under the condition of the carbon limitation. From the various rate of experiments, it was found that specific rate of enzyme production was decreased with an increase of specific growth rate. In order to obtain a high production of enzyme, the concentration of glucose in feed stream was increased 50g/1 to 200g/1. When glucose concentration was increased the cell concentration was proportionally increased. However but enzyme production was not increased proportionally but slightly; i.e. ezyme production was 3.18 U/ml with 14.5 g/l of cell at 50g/l of glucose and it was 3.52 U/ml with 46.7 g/l of cell at 200g/1 of glucose. Overall cell growth yield also decreased slightly from 0.40 to 0.35 at a high concentration of glucose.
It was also convinced that protease accumulated in the culture broth did not affect the degradation of carboxymethyl cellulase during fermentation.
As a nitrogen source, ammonium sulfate was superior to other inorganic nitrogen sources tested in terms of enzyme production.
유전자 재조합 미생물인 Bacillus megaterium pCK108 로부터 섬유소 분해 효소(carboxymethyl-cellulase; CMCase)를 대량 생산하기 위하여 고농도 배양을 수행하였다. 이때 배지를 대수적으로 공급하는 유가식 배양으로 세포의 비성장속도를 일정하게 유지시켜준 결과 낮은 비성장 속도에서 효소의 높은 비생성속도를 나타내었다. 비성장속도가 0.03 에서 배지의 포도당의 농도를 50g/l, 100g/l 또한 200 g/l로 증가시켜서 세포의 최대 농도 47.6g/l, 효소의 농도 3.56 U/ml 를 얻을 수 있었다. 그러나 포도당 농도가 증가할수록 효소의 비생성속도는 감소하는 불리한 양상을 나타내었다.
고농도배양에 필요한 무기질소원을 조사한 결과 ammonium sulfate의 농도가 증가할수록 단위 세포당 효소 생산량이 증가하였다. 고초균에서 많이 분비하는 단백질 분해 효소가 섬유소 분해 효소에 미치는 영향을 조사한 결과 큰 영향을 주지않음을 알 수 있었다.
