• Microbiology and Biotechnology Letters
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• v.21 no.5
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• pp.511-512
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• 1993

The production of vinegar containing high acetic acid concentration was carried in a single stage fed-batch culture. The initial and residual ethanol concentration were 50.0g/l and 5.0g/l, respectively, and the ethanol concentration was maintained from 5.0g/l to 10.0g/l during fedbatch culture. The fermentation temperature was decreased by 1C for every increase of 2.0% in acidity. The maximum productivity was 2.53g/l-hr and the acidity was 16.08% after 40 hours of acetic acid fermentation.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.319-323
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• 2005

This study is concerned with development of efficient culture methods for lactic acid fermentation of Lactobacillus sp. RKY2. The cell-recycle repeated batch fermentation using cheese whey and corn steep liquor as raw materials was tried in order to further enhance the productivity of lactic acid. In addition, fermentation efficiencies could be considerably enhanced by cell-recycle continuous culture. Through the cell-recycle repeated batch fermentation, lactic acid productivity was maximized to 6.34 $g/L{\cdot}h,$ which corresponded to 6.2 times higher value than that of the batch fermentation. During the cell-recycle continuous fermentation, the last dry cell weight at the end of fermentation could be increased to 25.3 g/L.

• KSBB Journal
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• v.25 no.2
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• pp.187-192
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• 2010

We designed the optimal operational strategy in repeated fed-batch ethanol fermentation using Sacchromyces cerevisiae ATCC 24858 in views of ethanol yield, specific ethanol production rate, and ethanol productivity, when the aeration rate were controlled at 0.0 and 0.33 vvm. Coincidentally, the time intervals of withdrawal-fill of culture medium (24 and 36 h) were investigated. Ethanol yield and ethanol productivity when the aeration was carried out at 0.33 vvm were superior to those when the aeration was not carried out. Additionally, those parameters when the time interval of withdrawal-fill of culture medium was 24 h were superior to those when time interval of withdrawal-fill of culture medium was 36 h. The total ethanol production reached at the greatest value, 703.8 g-ethanol, when the aeration was carried out at 0.33 vvm and the time interval of withdrawal-fill of culture medium was 24 h. In this study, we verified experimentally the necessity of designing the operational strategy for increasing ethanol production in terms of aeration rate and time interval of withdrawal-fill of culture medium in the repeated fed-batch ethanol fermentation.

• Journal of Microbiology and Biotechnology
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• v.1 no.2
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• pp.126-129
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• 1991

In order to produce ${\gamma}-linolenic$ acid by Mucor sp. KCTC 8405P. the fungus was cultivated in fed-batch culture with two phases. i.e., growth in yeast-like form and induction to hyphal growth by pH shift of the culture medium during cultivation. The synchronous growth of the fungus into the appropriate sizes was important for the high density cell culture of this dimorphic fungus. Dissolved oxygen concentration in the medium did not affect degree of unsaturation of fatty acids and ${\gamma}-linolenic$ acid content. Under the culture conditions applied in this experiment. the fungus was found to produce 100 g/l dry mycelia containing 40% of the lipids, where ${\gamma}-linolenic$ acid comprised about 9% of the total extractable fatty acids.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.6
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• pp.459-464
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• 2004

The objective of this study is to improve cephalosporin C (CPC) production byoptimization of medium and culture conditions. A statistical method was introduced to optimize the main culture medium. The main medium for CPC production was optimized using a statistical method. Glucose and corn steep liquor (CSL) were found to be the most effective factors for CPC production. Glucose and CSL were optimized to 2.84 and $6.68\%$, respectively. CPC produc­tion was improved $50\%$ by feeding of $5\%$ rice oil at day 3rd and 5th day during the shake flask culture of C acremonium M25. The effect of agitation speeds on CPC production in a 2.5-L bio­reactor was also investigated with fed-batch mode. The maximum cell mass (54.5 g/L) was obtained at 600 rpm. However, the maximum CPC production (0.98 g/L) was obtained at 500 rpm. At this condition, the maximum CPC production was improved about $132\%$ compared to the re­sult with batch flask culture.

• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.321-326
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• 2000

To examine the feasibility of the long-term production of the human granulocyte colony stimulating factor (hG-CSF) using the $_{L}-arabinose$ promoter system of Escherichia coli, flask relay culture and cyclic fed-batch culture were performed. In the flask relay culture, it was found that the pismid was maintained stably up to about 170 generations in an uninduced condition, whereby the cells could also maintain the capability of expressing hG-CSF expression were maintained stably up to at least 100 generations. In contrast, in the cyclid fed-batch culture, segregational plasmid instability was observed within about 4 generations after induction, even though the cell growth and hG-CSF production reached their maximum balues, 78.0 g/l of dry cell weight and 7.0 g/l of hG-CSF, respectively. It would appear that, when compared to the flask relay culture, the high-cell density and high-level expression of hG-CSF in the cyclic fed-batch cultrure led to the segregational plasmid instability; in other words, a severe metabolic burden existe on the cells due to the high-level expression of hG-CSF. Accordingly, based on these long-term cultures, the segregational and structural plasmid instability was observed and a strategy to overcome such problems could be designed.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1947-1953
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• 2006

There have been a number of studies of methods for recycling animal wastewater to provide new bioresources. In the present work, a marine algal culture medium, designated KEP II, was prepared by adding swine waste (3% v/v) fermented by soil bacteria to a dilution of f/2 culture medium (CT). When Phaeodactylum tricornutum was grown in batch culture in KEP II, the cells lasted long at the exponential phase producing the specific growth rate and biomass; the production of total amino acids and secondary metabolites rose up to 5-fold. It also substantially enhanced the maximum quantum yield of photo system (PS) II of P. tricornutum, greatly increased the level of thylakoid membranes containing PS, and stimulated the production of pyrenoids, including enzymes for $CO_2$ fixation in chloroplasts. KEP II should improve the cost efficiency of industrial mass batch cultures and the value of microalgae for long-term preservation of fresh aquaculture feed as well as production of anticancer and antioxidant agents. Specifically, a low-cost medium for growing the diatoms of aquaculture feed will be economically advantageous.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.287-290
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• 2000

To examine effects of agitation and aeration as well as adding of glucose and yeast extract on cell growth and polysaccharide production by Paecilomyces japonica, batch culture was carried out at 5L jar fermenter at $27^{\circ}C$ with the initial pH 7 for 7 days cultivation(innoculum size 2%, working volume 3L). Media compositions(g/L) were 30 glucose, 20 yeast extract, 0.5 $KH_2PO_4$, $0.1\;CuCl_2\;{\cdot}\;2H_2O$. Optimum culture conditions of agitation and aeration in batch culture were 400 rpm and 1.0 vvm, resulting in 23.1 g/L biomass and 2.5 g/L polysaccharide. Additional feeding of glucose and yeast extract with a pulse mode conferred an advantage on cell growth and polysaccharide production with showing the results of 29.2 g/L and 3.3 g/L, respectively.

• KSBB Journal
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• v.5 no.3
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• pp.269-277
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• 1990

Methylobacillus sp. SK1, an obligate methylotroph, was cultivated in a fed-batch culture using DO as a methanol feeding indicator with a micro computer-aided control system. While 2.07g/l of cell density was obtained after 13 hr in the batch culture (initial methanol concentration: 1.0%(v/v)),45.3g/l of cell density was obtained after 17 hr by feeding methanol and metal ions in the fed-batch culture with oxygen supply. The high-density biomass was obtained in short cultuivation time by fed-batch culture with feedback control, and consequently the biomass productivity was significantly increased. It was mainly due to extension of logarithmic growth period by methanol feeding without methanol inhibition and intensive aeration without DO limitation with microcomputer-aided control system.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.225-230
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• 2004

A plasminogen kringle domain 1 to 3, rKl-3, was expressed in Escherichia coli under the control of T7 promoter. For the cost-effective production of rKl-3, the induction process was analyzed and optimized. Induction characteristics with lactose were analyzed in terms of induction time and inducer concentration in various culture conditions including batch and high-cell-density fed-batch cultures. In the fed-batch culture, the induction around 6 h after initiation of the DO-stat fed-batch culture resulted in the highest expression level of rKI-3 among the induction points examined. The highest demand of oxygen at this point was crucial for the maximum expression level of rKI-3. As the lactose concentration increased, the expression level also increased, though the expression level showed a plateau above a concentration of 14 mM of lactose. Lactose acted less specifically than IPTG since most of it was hydrolyzed to glucose and galactose. However, using lactose, the cell growth and the maximum expression level of rKl-3 increased by 20% and 24%, respectively, compared with those using IPTG in the fed-batch culture. The lactose seemed to be hydrolyzed by intracellular and extracellular $\beta$-galactosidase liberated by cell lysis at the same time. Residual concentration of glucose was maintained to a a limit of detection by high performance liquid chromatography, and galactose was not consumed by the host strain Escherichia coli BL2l(DE3).