• Applied Biological Chemistry
• /
• v.37 no.6
• /
• pp.427-432
• /
• 1994

The effectiveness of the resting cells of a photosynthetic bacterium, Rhodocyclus gelatinosus KUP-74, was investigated on the production of extracellular ${\delta}-aminolevulinate$ (ALA). The ALA generating system with 1.05 mg cells per milliliter required 6 hr-incubation to obtain maximal yield of extracellular ALA. Under this condition ALA inducers, i.e., levulinate or L-glutamate showed relatively low effects to increase extracellular ALA production. Instead, the volume of the system and proper cell density appeared to be important factors for effective production of the ALA. The life-span of the resting cells was remarkably extended to maintain stable production of the ALA by immobilization of cells.

• Korean Journal of Food Science and Technology
• /
• v.28 no.5
• /
• pp.970-973
• /
• 1996

Effect of cell density on the xylitol production from xylose by Candida parapsilosis KFCC 10875 was investigated. The concentrated cells were obtained by centrifugation of culture broth. The xylitol production rate was maximum at the cell concentration of 20 g/l and the specific xylitol production rate decreased when the cell concentration was increased due to oxygen limitation. Effect of the initial concentration of xylose on the xylitol production was also examined using the concentrated cells of 20 g/l. The xylitol production rate, specific xylitol production rate, and xylitol yield from xylose were maximum at 170 g/l xylose. Above 170 g/l xylose, the xylitol production rate was remarkably decreased. The concentrated cells could also be obtained by adjusting the dissolved oxygen (DO) during fermentation. The rapid accumulation of cells up to 20 g/l was achieved by maintaining an increased level of DO during the exponential growth phase and then, for the efficient xylitol production, the DO was changed to a low level in the range of 0.7-1.5%. A fed-batch fermentation of xylose by adjusting the DO level was carried out in a fermentor and the final xylitol concentration of 140 g/l from xylose of 200 g/l could be obtained for 56 h fermentation.

• Applied Biological Chemistry
• /
• v.38 no.1
• /
• pp.1-6
• /
• 1995

An optimal condition for the continuous production of ${\delta}-aminolevulinate$(ALA) was investigated using high concentrated resting cells of Rhodocyclus gelatinosus KUP-74. The increase of the amount of extracellular ALA versus the concentration of resting cells showed rectangular hyperbolic pattern until 20 mg cells/ml, but no further increase in the ALA amount by increasing its concentration was occurred. The highest yield of the extracellular ALA was observed after 3 hr of incubation of 1 ml reaction system containing 20 mg cells, 4 mM levulinate and 5 mM L-glutamate. On the other hand, the immobilized cells prepared by Ca-alginate inclusive method needed to incubate for 6 hr with 6 mM levulinate and 10 mM L-glutamate to give maximal yield of the extracellular ALA. In addition, under these conditions the resulted continuous productivities of the ALA by immobilized cells and highly concentrated resting cells were appeared 50 percent decreases after incubations for 185 hr and 100 hr, respectively, and the method of the cells to be immobilized was more efficient to recover the extracellular ALA produced.

• KSBB Journal
• /
• v.7 no.4
• /
• pp.247-251
• /
• 1992

The effect of biomass concentration of Saccharomyces cerevisiae ATCC 24858 on specific growth rates, biomass yields, ethanol yields and productivity in the batch fermentation of rotary shaker was investigated. The specific growth rate decreased according to the increase in the biomass density and finally became zero at a biomass concentration, 55g/L. The ethanol yield $Y_{p/s}$ represented a constant value, 0.43, regardless of the change of biomass concentrations. However, the biomass yield $Y_{x/s}$ showed a trend to diminish in values with augmentation of biomass density and ultimately to reach zero at 55g/L of biomass concentration. The ethanol productivity increased linearly with biomass concentration so that, in case of initial sugar concentration, 170g/L, the productivity for 55g/L of biomass density rose up to 30g/L$\cdot$hr for all the batch fermentations. And also the ethanol concentration inhibiting completely the growth was verified 95g/L by applying experimental data to Luong's equation.

• KSBB Journal
• /
• v.19 no.1
• /
• pp.17-26
• /
• 2004

In this study the extracellular production of 5-aminolevulinic aicd (ALA) by recombinant E. coli BL2l (DE3) pLysS harboring the plasmid pFLS45 are investigated. Optimum concentrations of succinic acid and glycine for cell growth and ALA production were found to be 30 mM and 15 mM, respectively. Levulinic acid (LA) as an inhibitor of ALAD was added to the culture medium in the end of exponential cell growth phase and its optimum concentration was 30 mM. Growth of recombinant E. coli BL2l (DE3) pLysS (pFLS45) was largely dependent upon the pH value of culture medium. When the pH of culture medium was in the range of 6.0 and 6.5, high cell mass and ALA production were obtained. IPTG induction for the expression of the fusion gene did not enhance the production of ALA. Recombinant cell grew at 30't faster than at 37$^{\circ}C$, but ALA productivity was lower than at 37$^{\circ}C$. Repeated addition of glycine, succinic acid, and LA increased the production of ALA and the inhibition of intracellular ALA dehydratase activity, with up to 1.3 g/L ALA having been produced in the cultivation.

• Korean Journal of Food Science and Technology
• /
• v.20 no.1
• /
• pp.28-33
• /
• 1988

The optimum conditions for growth and lipid production of Rhodotorula marina IFO 0879 were investigated. The optimum temperature and pH of cultivation was $30^{\circ}C$ and pH 6.0-7.0, respectively. During shaking of the culture for 8 days at $30^{\circ}C$, the maximum cell biomass of Rh. marina was 9.82g per liter of the medium, and the lipid content obtained was 35.4(w/w) of the dry cell biomass. Lactose and glucose were the most effective carbon sources for the lipid production. Ammonium sulfate was found to be the most effective nitrogen in culture medium the growth of the yeast was retarded, whereas its growth was favored at high concentrations with decreased lipid yield. When lacose was added during fermentation, in the initial stage cell biomass and lipid production were lower than those of the control, but in the later stage the trend were reversed. The major fatty acids of yeast lipid were palmitic acid(20.3%), oleic acid(46.6%) and linoleic acid(16.2%)

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 1978.10a
• /
• pp.205.3-205
• /
• 1978

Methanol이용 미생물의 집적배양을 통해 토양 및 하수로부터 분리하여 그 중에서 비교적 생육속도가 빠른 균주를 선별하였다. 이 균주는 형태적, 생리적 특성에 따라 Methylomonas methanolica로 동정되었으며 obligate methylotroph 이었다. 균체 생산량을 높이기 위한 배지조성과 배양 최적조건을 검토한 결과, 탄소원으로는 methanol 0.8%(v/v), 질소원은 $(NH_4)_2SO_4$ 0.6%, 금속이온은 $MgSO_4.$ $7H_2O$ 0.1%이었고, 최적 pH는 6.3, 최적 배양온도는 $32.5^{\circ}C이었으며,$ 생육인자는 요구되지 않았다. 그리고 최적 배양조건에서 1ι용 fer-mentor를 사용하여 회분배양을 하였을 때 최대 비증식속도 0.19$hr^{-1}$, 균체수율은 0.47g dry cell/g-methanol이었다. Chemostat를 이용한 연속배양시 균체생산을 위한 최적희석률은 D=0.1 $hr^{-1}$이었고 이때의 균체생산속도는 0.21g- dry cell/hr이었다. 생산된 건조균체의 단백질과 핵산함량은 각각 73%, 12% 이었다.

• Journal of Life Science
• /
• v.14 no.1
• /
• pp.167-173
• /
• 2004

The optimal conditions for the continuous production of $\gamma$-aminobutyric acid by immobilization of Lactobacillus brevis BH-21 using column type reactor were investigated. The optimal conditions of operation were 2.2 mm diameter bead of 3.0% sodium alginate at 10 mL/h of substrate feeding rate. Continuous production by immobililzed cells showed the highest productivity with replacement of fresh medium in every 48h for fourth fermentatoin cycle following the rendition of $\gamma$-aminobutyric acid productivity. A productivity of $\gamma$-aminobutyric acid could be obtained for 25 days by continuous column type reactor under optimal conditions.

• KSBB Journal
• /
• v.4 no.3
• /
• pp.253-258
• /
• 1989

It was investigated that the influent sugar concentration and the dilution rate have an influence on the ethanol fermentation characteristics at steady state in a chemostat culture of K. fragilis using Jerusalem Artichoke juice as substrate. And also the optimum condition of high ethanol productivity and low residual sugar output in the ethanol production by K. fragilis, was clarified to be given at a dilution rate of 0.22/hr and at an influent sugar concentration of 85g/l.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 1975.07a
• /
• pp.110.4-111
• /
• 1975

식품공장에서 배출되는 폐액에 효모를 배양, 폐수의 처리와 함께 생산되는 균체를 이용하고 tapioka 주정 증류폐액을 이용하여 균체생산을 위한 최적조건및 수율을 검토하였다. 그 결과 Saccharomyces 속이 나 Candida속의 단독배양에 비하여 이들 Saccharomyces 속과 Candida 속을 혼합배양 했을 때가 효모의 수율이 높음을 알았으며, 이때 얻어지는 균체의 조단백함량은 54∼60％ 이었다.