• Journal of Ginseng Research
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• v.4 no.2
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• pp.133-145
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• 1980

In order to find out the inhibitors of acetic acid fermentation in Korean ginseng (Panax Sin son C. A. Meyer), total aglycone, panaxadiol, panaxadiol, oleanolic acid and ${\beta}$ -sitosterol were added to the basal medium, respectively, and a surface culture was carried out at 30$^{\circ}C$. The results were as follows: 1 . Saponins lost their activity to inhibit the acetic acid fermentation by hydrolysis. 2 Panaxadiol inhibited slightly, and the degree of inhibition was about 1/300 of that of free saponins. 3. Panaxadiol and oleanolic acid inhibited silighly similar to total aglycone. 4. Acetic acid fermentation was stimulated at the early stage when ${\beta}$-sitosterol was added to the media below the level of 0.000815%. But the fermentation was inhibited when media contained it more than that media 5. An over-oxidation of acetic acid was observed when the media contained total aglycone. panaxadiol, panaxatriol, oleanolic acid and ${\beta}$-sitosterol, respectively, while the media which contained sucrose, ginseng extracts ginseng saponins was shown not to be over-oxidized.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.659-664
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• 1994

In order to predict gas hold-up and oxygen transfer rate during sisomicin fermentation employing air lift fermentor, simulated media similar to fermentation broths in rheological proper- ties were prepared and used. Rheological properties of fermentation broths from 40 hours and 60 hours of cultivation were analyzed by applying to Power's Law equation. Regardless of addition and no addition of MgSO$_{4}$, the tendencies, that n value was decreased and K value was increased as aeration rate was increased, were shown. Simulated media of twelve different fermentation broths were formulated in a range of 0.7 to 2.1% CMC, and the values of gas hold-up and k$_{L}$a depending on superficial air velocity were measured using these simulated media. And the relation- ships, $\varepsilon$=$\alpha$U$_{Gr}$$\beta$, K$_{L}$a=$\gamma$U$_{Gr}$$\delta$ were obtained, and these equations are thought to be used to predict the values of gas hold-up and k$_{L}$a during fermentation.

• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.316-321
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• 1994

We investigated the possibility of industrial application and economit process of high temperature fermentation by thermotolerant alcohol producing yeasts as previously reported. From the 20% glucose media, the RA-74-2 produced 11.8% (v/v) ethanol at $32^{\circ}C$ (0.5% inoculum) and 10.6% (v/v) ethanol at $40^{\circ}C$ (3% inoculum), respectively. Also, 11.3% (v/v) ethanol was produced for 96 hours in the temperature-gradient fermentation. These results suggest that the RA-74-2 could isuccessfully be applied to save the cooling water and energy in industrial scale without re-investment or modification of established fermentation systems. When potato starch was used as the substrate for the RA-74-2, high temperature fermentation above $40^{\circ}C$ was more appropriate for industrial utilization because organic nitrogen was not necessary to economical fermentation. As the naked barley media just prior to industrial inoculation, taken from the Poongkuk alcohol industry Co., were used, 9.6% (v/v) ethanol was produced at $40^{\circ}C$ for 48 hours in jar-fermentor scale (actually, 9.5-9.8% (v/v) ethanol was produced at 30~$32^{\circ}C$ for 100 hours in industrial scale). The ethanol productivity was increased by the high glucoamylase activity as well as the high metabolic ratio at $40^{\circ}C$ Therefore, if the thermotolerant yeast RA-74-2 would be used in industrial scale, we could obtain a high productivity and saving of the cooling water and energy. Meanwhile, the RA-912 produced 6%(v/v) ethanol in 10% glucose media at $45^{\circ}C$ and showed the less ethanol-tolerance compared with industrial strains. As the produced alcohol was recovered by the vacuum evaporator at $45^{\circ}C$ in 15% glucose media, the final fermentation ratio was enhanced (76% of theoretical yields). This suggest that a hyperproductive process could be achieved by a continuous input of the substrate and continuous recovery of the product under vacuum in high cell-density 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.

• Journal of Microbiology and Biotechnology
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• v.4 no.3
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• pp.222-229
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• 1994

In order to develop a method of economical production and to reduce energy-consumption in fuel alcohol production, we investigated the fermentation characters of two newly selected thermotolerant yeasts. The RA-74-2 showed stable and superior fermentability between 30 and $40^{\circ}C$ in 20% glucose media in comparison to the industrial strains. The optimum concentration of glucose for economical fermentation at $40^{\circ}C$ was 15-18%, and organic nitrogen was necessary for a satisfactory fermentation. The optimum pH was 4.0 and aeration was adversed for high temperature fermentation. Agitation was an important factor at $40^{\circ}C$ and the addition of magnesium ion 0.2% was required in this experiment. When the inoculum was increased, ethanol productivity as well as the speed of fermentation increased. On the other hand RA-912, which can grow at $48^{\circ}C$, showed similar fermentability between 30-$45^{\circ}C$ in 20% glucose media As the concentration of substrate decreased, fermentation ratio increased at $45^{\circ}C$ (45%, 65%, 95% fermentation ratio in 20%, 15%, 10% glucose media, respectively). Also, requirement of organic nitrogen and magnesium ion in RA-912 was similar in RA-74-2. The optimum pH for fermentation was 5.0, and the effects of agitation were enhanced at $37^{\circ}C$ than at $45^{\circ}C$. As the inoculum was increased, fermentation speed became more enhanced but the ethanol productivity was less affected. RA-912 showed fermentability with various substrates. Among the substrates used, inulin was the most promising substrate for the high-temperature fermentation. When 14.5% inulin was used as the substrate, 93% and 55% fermentation ratios were shown at $37^{\circ}C$ and $45^{\circ}C$, respectively.

• Journal of Environmental Health Sciences
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• v.17 no.1
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• pp.120-128
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• 1991

Saccharomyces cerevisiae was immobilized by incubating iron oxides with calcium alginate, and by polyacrylamide entrapment to use repeatedly for the conversion of glucose to ethanol. Magnetic and non-magnetic immobilized yeast and polyacrylamide immobilized yeast were compared with the native yeast a batch-fermentation of ethanol from glucose. Three kinds of immobilized yeast tended almost identically, having ethanol productivity as well as the final yield about the same to what was found for the native yeast. The long-term operational stability of three kinds of immobilized yeast were significant difference according as immobilized yeast activation or non-activation before ethanol fermentation. In the non-activation they lost their activity of fermentation rapidly in the beginning stage an slower at a later stage. On the other hand, in the activation with nutrient media, their activities were increased to some extent and stable in the later stage. The cell count of three kinds of immobilized yeast after activiation by incubating nutrient media, increased by a factor of about 45 to 48, whereas the fermenting capacity increased by a factor of 174 to 178. In the prearation of immobilized biocatalysts, magnetic matter does not seem to have any adverse affect on the properties of the microorganism. The immobilized biocatalysts by utilizing magnetic matter have some advantages, especially in application of viscous media or insoluble particle-containing media, for this work was linked with microbial utilization of environmental wastes and elimination of envirnmental pollutant.

• Journal of Microbiology and Biotechnology
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• v.7 no.1
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• pp.62-67
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• 1997

To enhance the hyperproductive and low energy-consuming ethanol fermentation rate, the thermotolerant yeast S. cerevisiae RA-74-2 cells were immobilized. An efficient immobilization condition was proved to be $1.5{\%}$ (w/v) alginate solution, neutral pH and 20 h activation of beads. The fermentation characteristics and stability at various temperatures were examined as compared with free S. cerevisiae RA-74-2 cells. The immobilized cells had excellent fermentation rate at the range of pH 3-7 at 30-$42^{\circ}C$ in 15-$20{\%}$ glucose media. When the seed volume was adjusted to 0.12 (v/v) (6ml bead/50 ml medium), $11{\%}$ (w/v) ethanol was produced during the first 34 hand $12.15{\%}$ (w/v) ethanol [$95{\%}$ (w/v) of theoretical yield] during the first 60 h in $25{\%}$ glucose medium. In repetitive fermentation using a 2 litre fermentor, 5.79-$7.27{\%}$ (w/v) ethanol [76-$95{\%}$ (w/v) of theoretical yield] was produced during the 40-55 h in $15{\%}$ glucose media. These data suggested the fact that alginate beads of thermotolerant S. cerevisiae RA-74-2 cells would contribute to economic and hyperproductive ethanol fermentation at high temperature.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.709-715
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• 2013

The waste from beer fermentation broth (WBFB) has been found an excellent and inexpensive resource for bioethanol production. We tried to evaluate the saccharification and fermentation capabilities of WBFB to confirm its effectiveness for bioethanol production. The saccharification potentials of the WBFB were evaluated at various temperatures (30, 40, 50, 60 and $70^{\circ}C$). It was found that the saccharification capabilities increased with temperature and highest reached maximum at $60^{\circ}C$ and $70^{\circ}C$ after 4h. Ethanol production from a mixture of WBFB and chemically defined media (CDM) without addition of any microbial species confirmed the fermentation capabilities of WBFB. Simultaneous saccharification and fermentation were performed using WBFB, starch solution and CDM as culturing media. The maximum yield of bioethanol production was obtained at $30^{\circ}C$. The saccharifying enzymes and the yeast cells present in WBFB were essential factors for the production of bioethanol from WBFB without any additional enzymes or microbial cells.

• Journal of Microbiology and Biotechnology
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• v.1 no.3
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• pp.202-206
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• 1991

To produce acetoin as a precursor of the tetramethylpyrazine flavor compound from citrate by Lactococcus lactis ssp. lactis biovar. diacetilactis FC1, fermentation factors such as inital pH of culture media, temperature, concentration of Na-citrate, thiamin-HC1 and sugars were examined. The best acetoin production was achieved with initial pH in the culture media of 5.5, fermentation temperature of $34^{\circ}C$, Na-citrate concentration of 3%, addition of thiamin-HC1 at 2 mg/l and galactose as a carbon source. When fermentation was carried out under the optimum conditions, the exhaustion of Na-citrate and the production of acetoin took simultaneously and acetoin reached the maximum content, 80 mmole/l after 20 hours.

• Journal of Microbiology and Biotechnology
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• v.1 no.4
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• pp.281-284
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• 1991

To investigate the optimum conditions for the production of ammonia as a precursor of tetramethylpyrazine flavor compound from arginine by Lactococcus lactis ssp. lactis biovar. diacetilactis FC1, fermentation factors such as initial pH of culture media, fermentation temperature, concentration of arginine-HC1, and sugars were examined. The optimum conditions were initial pH 5.5 of the culture media, fermentation temperature of $34^{\circ}C$, 6% (w/v) of arginine-HC1, and 1% (w/v) of galactose as a carbon source. Under the optimum fermentation conditions, 40 mmole/l of ammonia was produced after 40 h.