• Biotechnology and Bioprocess Engineering:BBE
• /
• 제1권1호
• /
• pp.22-25
• /
• 1996

An Exponetial feeding strategy has been frequently used in fed-batch fermentation of recombinant E. coli. In this feeding scheme, growth yield and initial cell concentration, which can be erroneously determined, are needed to calculate the feed rate for controlling specific growth rate at the set point. The effect of the incorrect growth yield and initial cell concentration on the control of the specific growth rate was theoretically analyzed. Insignificance of the correctness of those parameters for the control of the specific growth rate was shown theoretically and experimentally.

• KSBB Journal
• /
• 제4권3호
• /
• pp.271-275
• /
• 1989

본 논문에서는 Thalictrum rugosum 식물세포의 회분식 배양에 있어서 동역학적 특성들을 연구하였다. 본 실험에서 alkaloid의 생성은 일반적인 2차대사 산물의 생성 특성과 달리 세포성장에 비례함이 확인되었다. 세포 성장기의 비증식속도는 $0.20~0.25\;day\;^{-1}이었으며 FW / DCW 비가 배양상태를 나타내는 중요한 인자임을 알수 있었다. Cell yield는 0.36g cells/g sugar이었으며 berberine은 139mg/L까지 생성되었고 그중 120mg/L는 세포내에 존재하였다. 이를 specific content로 계산하면 dry cell weight의 1.10%가 된다. 세포 성장기에서 비증식속도와 당농도간의 관계는 Monod kinetics로 잘 기술될 수 있었다.

• 한국미생물·생명공학회지
• /
• 제28권5호
• /
• pp.298-302
• /
• 2000

Fermentation parameters were estimated by use of a vent gas analyzer coupled to a computer data acquisition system in cultivation of Phellinus linteus WI-001, pro-ducer of polysaccharides known to have potent anticancer activities. Oxygen uptake rate(OUR), a critical indicator of the cells activities, was calculated by applying oxygen mass balance. In addition, by dividing the oxygen uptake rate hy the total oxygen consumed, on-line estimation of the cells specific growth rate was successfully done. It was also possible to estimate cell concentration directly bt use of oxygen-cell yield($Y_{x/o}$ ) which was obtained based on a correlation between cell growth and total oxygen consumed.

• Journal of Microbiology and Biotechnology
• /
• 제18권5호
• /
• pp.918-925
• /
• 2008

Controlling the light energy and major nutrients is important for high cell density culture of cyanobacterial cells. The growth phase of Anabaena variabilis can be divided into an exponential growth phase and a deceleration phase. In this study, the cell growth in the deceleration phase showed a linear growth pattern. Both the period of the exponential growth phase and the average cell growth rate in the deceleration phase increased by controlling the light intensity. To control the light intensity, the specific irradiation rate was maintained above $10\;{\mu}mol/s/g$ dry cell by increasing the incident light intensity stepwise. The final cell density increased by controlling the nutrient supply. For the control of the nutrient supply, nitrate, phosphate, and sulfate were intermittently added based on the growth yield, along with the combined control of light intensity and nutrient concentration. Under these control conditions, both final cell concentration and cell productivity increased, to 8.2 g/l and 1.9 g/l/day, respectively.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제10권3호
• /
• pp.254-261
• /
• 2005

The over-expression of Bcl-2 has greatly improved the culture period, specific growth rate, and maximum viable cell density of NS0 cells culture under low serum condition. Further analysis of these data suggests that a saturation model of the Monod type can be used to represent the relationships of specific growth rate and initial serum concentration. The ${\mu}_{max}$ and $K_s$ for the Bcl-2 cell line is $0.927day^{-1}\;and\;0.947\%(v/v)$ respectively, which are $21\%$ greate and $7\%$ lower respectively than its control counterpart. Study on the amino acid supplementation revealed that Bcl-2 cell lines possess greater improvement in the specific growth rate and maximum viable cell density compared to the control cell lines. A further increase in the amino acid supplementation has resulted a $17\%$ decrease in specific growth rate and no improvement in maximum viable cell density in the control culture. However, the Bcl-2 cell line exhibited a better growth characteristic in this culture condition compared to that of control cell lines. The higher specific growth rate and maximum viable cell density of the Bcl-2 cell line in medium fortified with serum and MEM EM suggested a more efficient nutrient metabolism compared to that in the control cell line. The low serum and amino acid utilisation rate and the higher cell yield may prove to be important in the development of serum/protein free culture.

• 한국미생물·생명공학회지
• /
• 제23권4호
• /
• pp.479-484
• /
• 1995

The effect of initial cell concentration on the characteristics of ethanol fermentation was investigated in the batch fermentation of Saccharomyces cerevisiae ATCC 24858. The characteristics were investigated in the range of 60 to 230 g/l of the initial sugar concentrations and 0.5 to 85 g/l of the initial cell concentrations. When the initial cell concentrations were 27 g/l for 60 g/l of the initial sugar and 85 g/l for 230 g/l, the fermentation time required for the complete consumption of the initial sugar was one hour, respectively. The ethanol productivity increased with the initial cell concentration so that, in the case of 100 g/l of initial sugar, the productivity rose up to 55 g/l/hr at 55 g/l of the initial cell concentration. The specific growth rate decreased according to the increase in the initial biomass concentration and finally became zero at around 25 g/l of the cell concentration regardless of the initial sugar concentration. The specific ethanol production rate was constant as 1.02 g/l/hr up to 150 g/l of the initial sugar. However, the rates decreased sharply with the augmentation of concentration of the initial sugar above 160 g/l. The overall ethanol yield represented a constant value, 0.475 g/g irrespective of the initial cell and sugar concentrations. The overall biomass yietd showed a trend to diminish in values with the biomass and ultimately to reach zero more than 25 g/l of the initial cell concentration.

• Journal of Microbiology and Biotechnology
• /
• 제11권6호
• /
• pp.1055-1060
• /
• 2001

Experimental data for the on-line estimation of cell concentration and growth rate are presented. For this purpose, we utilized the on-line calculation of the oxygen uptake rate (OUR), which was derived from a liquid phase dynamic mass balance for the oxygen during the active growth phase in cyclosporin A (CyA) fermentation. The cell yield coefficient, based on the oxygen $(Y_{x/o})$for both suspended and immobilized cells of Tolypocladium inflatum, was estimated as $1.9 gDCW/gO_2$ from a very good linear correlation between the cell mass produced and the total oxygen consumed. The calculated yield showed a good agreement with the value of $(Y_{x/o})$ generated from the correlation between the cell growth rate and the oxygen uptake rate. In addition, further experimental data are given, which were also applied to determine the specific oxygen uptake rate of T. inflatum cells during the exponential phase of CyA fermentation. A theoretical basis for the analysis of these fermentation parameters is also provided.

• KSBB Journal
• /
• 제4권3호
• /
• pp.259-265
• /
• 1989

당근세포의 현탁배양에서 배지중 제한영양소인 인산염과 글루코우즈 농도에 대한 당근세포 배양특성에 관한 실험으로부터 다음의 결론을 얻었다. 1) 배지중의 글로코우즈와 인산염을 제한영양소로 하였을 때, 현탁배양 중의 글루코우즈의 농도 1.49g/l - 3.01g /l, 인산염의 농도 0.08mM - 1.06mM의 범위에서 세포성장 정체기에 도달하는 시간은 13.2hr-66.4hr였고 제한영양소의 전환율은 초기 글루코우즈와 인산염의 농도의 5~30% 범위내에 분포되었다. 2) 제한 영양소의 저농도범위에서의 농도변화에 따른 세포의 비성장속도, $\mu$는 $0.15day^{-1}$와 $0.3day^{-1}$사이의 값으로 일정한 경향을 보이지 않았는데, 이것은 제한요소가 저농도로 존재할 때 세포의 비성장속도에 미치는 영향이 적음을 알 수 있다. 3) 제한 영양소의 소모량과 세포증가량 사이에는 선형적 관계를 나타내며, 제한 영양소 글루코우즈에 대한 세포수율($Y_{x/sG}$)은 인산염 0.32mM, 글루코우즈 2.67g/l에서 $98.71{\times}10^{10}개\;/\;g로$ 최대값을 나타내었다. 4) 제한 영양소의 비($s_G/s_P$)에 대한 비성장속도, $\mu$ 및 세포수율($Y_{x/s_G}$는 두 농도의 비($s_G/s_P$)가 20mM/mM-120mM/mM 사이에서 임의적으로 분포하였다.

• KSBB Journal
• /
• 제5권1호
• /
• pp.75-80
• /
• 1990

돼지감자 착즙의 당농도를 50,80,110,190,250g/l로 하고 K.marxianus의 비증식속도,균체수율,알콜수율등을 발효액주으이 생성알콜농도및 당 소모량의 함수로 구명한 결과 다음의 결론을 얻었다. 생성알콜농도에 대한 비증식속도 및 알콜의 비생성속도의 함수관계는 알콜생성량이 낮을때 선형 함수관계를, 알콜생성량이 높을때는 지수 함수관계를 나타내었다. 균체의 증식은 생성알콜농도가 50g/l이상에서, 그리고 당의 소모량이 100g/l이상에서 잔여 당농도에 무관하게 정지되는 경향을 나타내었다. 비증식속도와 당 소모량사이에는 선형 함수관계를 나타내었으며,알콜 비생성속도와 당소모량사이의 함수관계는 초기당농도가 낮을때 선형 함수관계를 나타내었으나 초기당농도가 높아질수록 지수함수관계로 천이되었다. 균체수율및 알콜수율은 초기당농도에 무관하게 생성알콜농도 25g/l 부근에서 최대치를 나타내었으며, 알콜생성량이 증가함에 따라 초기 당농도가 증가할수록 완만하게 감소하였다. 이상의 함수관계로부터 K.marxianus의 알콜발효에 있어 한계 당농도는 110g/l근방으로, 한계 알콜농도는 50g/l근방인 것으로 추정되었다.

• 한국미생물·생명공학회지
• /
• 제17권5호
• /
• pp.504-509
• /
• 1989

Streptococcus lactis IFO 12007의 nisin 생산을 위한 발효조건을 검토하였다. Nisin 생성을 위한 포도당의 농도는 60g/ι이며 pH와 온도는 각각 6.5와 3$0^{\circ}C$이었다. 이 조건에서 최대 2,000IU/$m\ell$의 생산량을 보이며 이 때 specific glucose uptake rate: 0.59g/g/h, specific nisin productivity는 34924iu/g/h, growth yield는 0.24, 7시간 후 균체 생산량은 4.81g/ι이었다. 비성장속도는 온도와 pH에 의하여 영향을 많이 받으며 증식활성화 에너지는 1.35kca1/ mole이었다. 유가배양에 의하여 1420IU/$m\ell$의 nisin을 생산하며 연속배양은 0.38h$^{-1}$까지 가능하고 이때 nisin 농도는 740IU/m1, specific nisin productivity는 45000IU/g/h, true growth yield 는 0.144, maintenance energy는 207mg glucose/g-cell/h 이었다.