• Biotechnology and Bioprocess Engineering:BBE
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• 제5권5호
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• pp.340-344
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• 2000

Microbial oxidation of D-sorbitol to L-sorbose by Acetobacter suboxydans is of commercial importance since it is the only biochemical process in vitamin C synthesis. The main bottleneck in the batch oxidation of sorbitol to sorbose is that the process is severely inhibited by sorbitol. Suitable fed-batch fermentation designs can eliminate the inherent substrate inhibition and improve sorbose productivity. Fed-batch sorbose fermentations were conducted by using two nutrient feeding strategies. For fed-batch fermentation with pulse feeding, highly concentrated sorbitor (600g/L) along with other nutrients were fed intermittently in four pulses of 0.5 liter in response to the increased DO signal. The fed-batch fermentation was over in 24h with a sorbose productivity of 13.40g/L/h and a final sorbose concentration of 320.48g/L. On the other hand, in fed-batch fermentation with multiple feeds, two pulse feeds of 0.5 liter nutrient medium containing 600g/L sorbitol was followed by the addition of 1.5 liter nutrient medium containing 600g/L sorbitol at a constant feed rate of 0.36L/h till the full working capacity of the reactor. The fermentation was completed in 24h with an enhanced sorbose productivity of 15.09g/L/h and a sorbose concentration of 332.60g/L. The sorbose concentration and productivity obtained by multiple feeding of nutrients was found to be higher than that obtained by pulse feeding and was therefore a better strategy for fed-batch sorbose fermentation.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권1호
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• pp.11-17
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• 2001

To enhance the productivity and activity of nitrile hydratase in Rhodococcus rhodochrous M33, a glucose-limited fed-batch culture was performed. In a fed-batch culture where the glucose was controlled at a limited level and cobalt was supplemented during the fermentation period, the cell mass and total activity of nitrile hydratase both increased 3.3-fold compared to that in the batch fermentation. The productivity of nitrile hydratase also increased 1.9-fold compared to that in the batch fermentation. The specific activity of nitrile hydratase in the whole cell preparation when using a fed-batch culture was 120 units/mg-DCW, which was similar to that in the batch culture.

• 한국미생물·생명공학회지
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• 제51권2호
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• pp.184-190
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• 2023

Bioethanol has recently attracted much attention as a sustainable and environmentally friendly alternative energy source. This study aimed to develop a potential process for bioethanol production by fed-batch fermentation using instant dry yeast. To obtain the highest cell growth, we studied the influence of the initial sugar concentrations and pH of sugarcane molasses in batch fermentation. The batch system employed three levels of sugar concentrations, viz. 10%, 15%, 20% (w/v), and two levels of pH, 5.0 and 5.5. The highest cell growth was achieved at 20% (w/v) and pH 5.5 of molasses. The fed-batch system was then performed using the best batch fermentation conditions, with a molasses concentration of 13% (w/v) which resulted in high ethanol concentration and fermentation efficiency of 15.96% and 89%, respectively.

• KSBB Journal
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• 제16권4호
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• pp.415-419
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• 2001

Bacillus subtilis WB700에서 P43 프로모터를 사용하여 staphylokinase를 생산하기 위하여 배지 최적화 및 회분식 배양과 유가식 배양 두가지 시스템을 비교하였다. 여러 가지 질소윈 중에서는 tryptone이 가장 좋은 질소원 이었으며, MSR 배지를 사용한 경우 tryptone 15 g/L일 경우에 최적조건임을 알아내었다. MSR 배지에시 포도당을 제한 기질로 사용할 경우는 5 g/L일 때가 SAK의 발현에 최적 조건이었다. MSR 배지를 기본으로 이용하여 포도당 공급을 조절함으로서 발효조 내의 DO를 30%로 유지한 결과 오히려 MSR 배지를 이용하여 회분식 발효를 한 경우보다 좋지 못한 결과를 얻었으며, 이는 B. subtilis 숙주의 영양요구적 특이성과 P43 promoter의 stress 발생시 주 발현되는 특성 등에 기인한 것이라고 사료된다. MSR 배지를 이용하여 회분식 발효를 하였을 때 SAK 활성은 2880 unit이었고, 이때 배지 내로 분비된 SAK 농도는 455 mg/L이었다.

• Journal of Microbiology and Biotechnology
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• 제22권6호
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• pp.826-831
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• 2012

Acarbose, a pseudo-oligosaccharide, is widely used clinically in therapies for non-insulin-dependent diabetes. In the present study, S-adenosylmethionine (SAM) was added to selected media in order to investigate its effect on acarbose fermentation by Actinoplanes utahensis ZJB-08196. Acarbose titer was seen to increase markedly when concentrations of SAM were added over a period of time. The effects of glucose and maltose on the production of acarbose were investigated in both batch and fed-batch fermentation. Optimal acarbose production was observed at relatively low glucose levels and high maltose levels. Based on these results, a further fed-batch experiment was designed so as to enhance the production of acarbose. Fed-batch fermentation was carried out at an initial glucose level of 10 g/l and an initial maltose level of 60 g/l. Then, 12 h post inoculation, 100 ${\mu}mol/l$ SAM was added. In addition, 8 g/l of glucose was added every 24 h, and 20 g/l of maltose was added at 96 h. By way of this novel feeding strategy, the maximum titer of acarbose achieved was 6,113 mg/l at 192 h. To our knowledge, the production level of acarbose achieved in this study is the highest ever reported.

• Journal of Microbiology and Biotechnology
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• 제5권4호
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• pp.229-233
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• 1995

Acremonium chrysogenum was immobilized in ionotropic gel beads to develop semi-continuous production of cephalosporin C (CPC). Barium alginate beads were more stable than calcium alginate or strontium alginate beads in chemically defined media. The gel stability of Ba-alginate was further increased by cross-linking with polyethyleneimine (PEI). The presence of carboxymethyl cellulose inside Ba-alginate beads did not reduce mass transfer resistance. Ba-alginate microbeads that had little diffusion limitation increased CPC production rate 1.6 fold higher than that of normal beads. CPC fermentation with immobilized cells in Ba-alginate microbeads was performed continuously for 40 days by way of repeated fed-batch operations. Mathematical modeling was developed to describe the repeated fed-batch fermentation system. Results of the computer simulation agreed well with the experimental data, which made it possible to predict an optimal feeding rate that could maximize total CPC productions.

• Journal of Microbiology and Biotechnology
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• 제11권1호
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• pp.13-16
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• 2001

Maltose and soluble starch were used as secondary sources of carbon for glucoamylase production by Aspergillus awamori in solid state fermentation. During batch cultivation, maltose above 2.5%(w/w) repressed glucoamylase production, but, by adding either 2.5% (w/w) maltose or 1.25% (w/w) soluble starch to fed-batch cultivations, glucoamylase activity was increased by 15% and 170% over standard medium, respectively. The data showed that maltose is a weak inducer of glucoamylase production in solid stat fermentation.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.283-286
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• 2000

본 연구에서는 fed-batch를 통하여 Agaricus blazei의 균체증식과 다당체 생산을 증가시키고자 공급배지와 배지공급속도에 변화를 주어 균체증식과 다당체 생성에 미치는 영향을 비교 ${\cdot}$ 검토하였다. 유가식 배양에서의 최종균체량 및 다당체 생성량은 회분식 배양에 비해 훨씬 높았으며, 초기에 균체증식을 위해 공급배지로 yeast extract를 먼저 공급하고 4일째부터 다당체 생성을 위해서 glucose를 공급할 경우 균체량은 18.2 g/L, 다당체 생성량은 10.4 g/L를 생산하여 배양결과 최대 생산량을 나타내었다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권4호
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• pp.267-273
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• 2004

The optimization of culture conditions for the bacterium Pseudomonas aeruginosa BYK-2 KCTC 18012P, was performed to increase its rhamnolipid production. The optimum level for carbon, nitrogen sources, temperature and pH, for rhamnolipid production in a flask, were identified as 25 g/L fish oil, 0.01% (w/v) urea, 25 and pH 7.0, respectively. Optimum conditions for batch culture, using a 7-L jar fermentor, were 200 rpm of agitation speed and a 2.0 L/min aeration rate. Under the optimum conditions, on fish oil for 216 h, the final cell and rhamnolipid concentrations were 5.3 g/L and 17.0 g/L respectively. Fed-batch fermentation, with different feeding conditions, was carried out in order to increase, cell growth and rhamnolipid production by the Pseudomonas aeruginosa, BYK-2 KCTC 18012P. When 2.5 g of fish oil and 100 mL basal salts medium, containing 0.01 % (w/v) urea, were fed intermittently during the fermentation, the final cell and rhamnolipid concentrations at 264 h, were 6.1 and 22.7 g/L respectively. The fed-batch culture resulted in a 1.2-fold increase in the dry cell mass and a 1.3-fold increase in rhamnolipid production, compared to the production of the batch culture. The rhamnolipid production-substrate conversion factor (0.75 g/g) was higher than that of the batch culture (0.68 g/g).

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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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%.