• Journal of Microbiology and Biotechnology
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• v.13 no.2
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• pp.175-181
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• 2003

The production of a carotenoid astaxanthin, a growth-associated principal pigment, is limited in a batch cultivation, because a high glucose concentration severely inhibits the cell growth and also influences the carotenoid production. Therefore, a fermentation strategy including effective chemicals for the high-level production of cells and astaxanthin by a mutant strain Phaffia rhodozyma AJ-6-1 was developed in a fed-batch culture. First, a production medium for maximizing the cell and astaxanthin yields was formulated and optimized. Using this optimized medium, the highest cell and astaxanthin concentrations obtained were about 38.25 g/1 and 34.77 mg/1, respectively. In addition, an attempt was made to increase the amount of astaxanthin using effective chemicals such as ethanol and acetic acid, which are known at an inducer and/or precursor of carotenoid synthesis. When either 10g/1 ethanol or 5 g/1 acetic acid was added to investigate the resulting astaxanthin content, a relatively high astaxanthin concentration or 45.62 mg/l and 43.87 mg/1, respectively, was obtained, and the cell concentrations also increased slightly under these conditions. Therefore, these results imply that a fed-batch culture of the mutant strain P. rhodozyma AJ-6-1 could be effectively employed in the commercial production of astaxanthin, although the factors affecting the productivity remain to be elucidated.

• KSBB Journal
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• v.16 no.1
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• pp.30-35
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• 2001

High cell density culture of Bacillus thuringiensis was conducted in fed-batch culture and TCRC using a bioreactor incorporating ceramic membrane filter. Cell growth of B. thuringiensis in fed-batch culture increased linearly, which was well matched by the results of cell growth modeling. In spite of the slower growth rate during fed-batch culture, no spore formation was observed, which was contrary to the results of continuous culture. Changing culture mode to batch culture after fed-batch operation induced a 2.7$\times$$10^9$ CFU/mL spore concentration using a 300 g/L glucose feed concentration. In TCRC operation incorporating ceramic filter within the bioreactor, the effect of glucose feed concentrations on the cell growth and spore formation of B. thuringiensis was determined. A maximum cell concentration of 1.8$\times$$10^{10}$ CFU/ml, which corresponds to 82.6 g-cell/L, was obtained in the TCRC using a 50 g/L glucose feed concentration. In the TCRC, cell growth increased linearly and glucose concentration was limited, which agreed well with the results of cell growth modeling. No spore formation was observed except when 1 g/L of glucose was fed. Changing to batch culture induced a 1.2$\times$$10^{10}$ CFU/mL of spore concentration, which was the highest spore concentration obtained among the various culture modes examined. The optimal glucose feed rate was found to be 0.55 g-glucose/h.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.6
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• pp.753-757
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• 1999

The growth of rotifer, Brachionus rotundiformis was evaluated at different culture conditions. Rotifer was fed on condensed freshwater Chlorella. The productivity of rotifer in the high density culture system was compared to that of rotifer in the batch culture system, in which rotifer was fed on baker's yeast. The growth rate of rotifer increased as temperature increased in the culture system supplied with air or oxygen gas. The maximum density of rotifer in the culture systems supplied with air was in range of 16,300$\~$17,000 ind./ml at $24^{\circ}C$. In the culture systems supplied with oxygen gas, it ranged 26,300$\~$30,500 ind/ml at $28^{\circ}C$. When the concentration of dissolved oxygen in the culture system supplied with air reached to below 1 ppm or when the concentration of undissolved ammonia in the culture system supplied with oxygen gas reached 16.6$\~$22.6 ppm, the growth of rotifer decreased. When oxygen gas was supplied and pH was adjusted to 7, the maximum density of rotifer reached to 43,000 ind/ml at $32^{\circ}C$. The production costs for 10 billion rotifer in the high density culture and batch culture were 693,000 and 961,000 won, respectively. Therefore, it was concluded that the productivity of rotifer in the high density culture was higher than that in a batch culture.

• KSBB Journal
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• v.16 no.4
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• pp.415-419
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• 2001

To produce staphylokinase (SAK) in B. subtilis WB700, media optimization was carried out and the operation of batch and fed-batch fermentation were compared. Tryptone is a good nitrogen source and its optimum concentration in modified super rich(MSR) media is 15 g/L. When glucose is used as a limiting carbon source in the MSR media, 5 g/L of an optimum glucose concentration was identified for the SAK production under the control of P43 promoter. As the expression of P43 promoter is controlled by the limitation of oxygen, the SAK production was controlled at the 30% DO level in the fed-batch fermentation. Unexpectedly, batch fermentation using MSR media showed 1.5 times higher yield of SAK than that of the fed-batch fermentation. The main cause of the results comes from not achieving higher cell concentration in the fed-batch fermentation and the optimum expression level of P43 promoter under oxygen or nutrient limitations. We could not achieve the increase in cell concentration by any means in batch culture as well as fed-batch culture. The highest yield in the batch culture was 2880 units of SAK activity and 455 mg/L of secreted SAK.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.177-179
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• 2002

The process for the production of mannitol with fructose (5% to 25%) using Leuconostoc mesenteroides NRRL B-1149 was investigated. Optimization study for mannitol production was carried out in 8 liter batch or fed-batch cultures at $28^{\circ}C$, pH 5.0, without aeration. When 5% fructose was used in a batch culture fermentation, the yield of mannitol was 78% of theoretical. As the concentration of fructose was increased to 10% in a batch culture, the yield was reduced to 59.6% of theoretical. Using a fed-batch fermentation with 10% fructose, the yield was increased to 81.9%. When 15% fructose was used for a fed batch fermentation 5% fructose was initially added and the last 10% fructose was supplied continuously. The final yield of mannitol was 83.71% of theoretical. When 20% fructose was used, the yield was more higher, 89.48%.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.4
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• pp.234-236
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• 2002

A process for the production of mannitol from fructose (5% to 25%) using Leuconostoc mesenteroides NRRL B-1149 was investigated. Fermentations were carried out In batch or fed-batch fermentations without aeration at 28$\^{C}$, pH 5.0. When 5% fructose was used In batch culture fermentation, the yield of mannitol was 78% of that expected theoretically. When the frurtose concentration was Increased to 10%, the yield dropped to 59.6% of the theoretical value. However, In the fed-batch culture, using 10% fructose, the yield was 81.9% of the theoretical value. In a 15% fruttose fed-batch culture, with 5% fructose being added initially and the other 10% fructose being added as a continuous supply the final yield was 83.7% of the theoretical yield. When 20% fructose was used In the same manner, the yield was 89.5% of theoretical yield.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.338-341
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• 2000

An internal membrane bioreactor system was employed for continuous succinic ac id production from glucose in order to prove its performance and practicality. Succinic acid-producing Anaerobiospirillum succiniciproducens required more $CO_2$ for the proper growth and succinic acid production in cell recycled continuous culture than in batch culture. The maximum productivity obtained in cell recycled continuous culture was about 3.3 g/L-h which was ca. 3.3 times higher than that obtained in batch culture.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.271-274
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• 2000

A study was carried out to select a nitrogen source and the optimize the C/N ratio for the maximum cell growth of Phaffia rhodozyma in fed-batch culture. The yeast extract was the best organic nitrogen source. In the batch culture experiments, the highest cell yield was obtained 0.575 g-cell/g-glucose from 10 g/L and 10 g/L yeast extract. In the fed-batch experiments, the maximum cell concentration was obtained 33.1 g/L from the C/N ratio of 2:1 while the astaxanthin concentration of cell was Increased by increasing the C/N ratio, of feed medium.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.4
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• pp.254-254
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• 2002

A process for the production of mannitol from fructose (5% to 25%) using Leuconosyoc mesenteroides NRRL B-1149 was investigated. Fermentations were carried out in bat도 of fed-batch fermentations without aeration at 28℃, pH 5.0. When 5% fructose was used in batch culture fermentation, the yield of mannitol was 78% of that expected theoretically. When the fructose concentration was increased to 10%, the yield dropped to 59.6% of the theoretical value. However, in the fed-batch culture, using 10% fructose, the yield was 81.9% of the theoretical value. In a 15% fructose fed-bat도 culture, with 5% fructose being added initially and the other 10% fructose being added as a continuous supply, the final yield was 83.7% of the theoretical yield. When 20% fructose was used in the same manner, the yield was 89.5% of theoretical yield.

• KSBB Journal
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• v.17 no.3
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• pp.307-310
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• 2002

In order to obtain high density seed cells for biofiltration, we studied batch and fed-batch culture of P. putida. Studies were carried out to find optimum fermentation conditions such as pH, concentration of glucose and agitation speed. Specific growth rate of P. putida was dependent on agitation speed and a high rpm of 300 was necessary to carry out the efficient aerobic growth of P. putida. Specific growth rate was highest at pH 7. Feeding glucose and yeast extract continuously at the initial growth phase was the most effective way to get high cell density of P. putida.