• KSBB Journal
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• v.6 no.2
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• pp.189-194
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• 1991

The effect of wtlitc light on unaeraten growth of Baker's yeast and the accompanying ethanol production has been studied in a batch process at 27$^{\circ}C$. Over the 80-hour period of the Champagne yeast process without pH control, the cull growth was inhibited by the fluorescent light. Another observed difference between the runs is that the drop and subsequent rise in redox potential occurred much sooner in the fermentation with light than in the fermentation without light. This preliminary study indicated that ethanol production could be enhanced by light as the cell concentration is repressed. The possible pathway, shift of the sugar substrate toward ethanol and away from cells was manifested by another difference as well. As observed under the microscope, many of the yeast cells grown under light budded without dividing by the normal fission process as they did in the dark. Furthermore, the undivided and branched (light grown) cell did not agglutinate at the end of the fermentation process as did the distinct spherical (dark grown) cells.

• Journal of the Korean Wood Science and Technology
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• v.38 no.6
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• pp.561-567
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• 2010

In this study, we evaluated optimal conditions for ethanol production of the spruce hydrolysate (SH) obtained from diethyl oxalate pretreatment. Fermentable sugar concentration in SH was 29.04 g/${\ell}$ except arabinose. Monosaccharides obtained from the oligomer degradation were mainly mannose (39.26 g/${\ell}$) and galactose (12.83 g/${\ell}$). Concentration of 5-HMF and furfural which are inhibitors on ethanol fermentation were 0.09 g/${\ell}$ and 0.04 g/${\ell}$ respectively. Concentration of acetic acid and total phenolic compounds in SH were 1.4 g/${\ell}$ and 2.83 g/${\ell}$. Ethanol production using hydrolysate was 11.7 g/${\ell}$ at optimal pH 6.0 after 48 h. Specific ethanol production was 0.15 (g/(${\ell}^*h$)) at pH 5.0 and 5.5. while that was 0.24 (g/(${\ell}^*h$)) at pH 6.0. Specific ethanol production has difference depend on initial pH for fermentation. Ethanol production was 14.3 g/${\ell}$ after 48 h when xylanase 20 IU was added in SH for degradation of oligomer during fermentation. It implied that ethanol production increased by 22.2% compare with control (without xylanase).

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.562-565
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• 2011

In this study, we developed a bioprocess using Clostridium ljungdahlii as a biological catalyst to produce bio-ethanol, and the effect of pH on microbial growth and ethanol production was investigated. From the results of fermentation at various initial pH condition without pH control, pH of fermentation broth decreased to 4.5 within 24 h due to accumulation of by-product acetic acid and both microbial growth and ethanol production were stopped. The experimental result of initial pH 8 showed the highest microbial growth and ethanol production (0.53 g/L), since the pH drop was relatively slow. From the experiment of pH 7 maintained fermentation using pH controllable bioreactor, the maximum cell dry weight of 1.65 g/L and the maximum ethanol concentration of 1.43 g/L were obtained within 24 h. In conclusion, the C. ljungdahlii growth was enhanced by pH maintenance of neutral range, and the ethanol production was also enhanced based on the growth-associated ethanol production characteristics of C. ljungdahlii.

• Microbiology and Biotechnology Letters
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• v.15 no.5
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• pp.340-345
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• 1987

Microorganisms capable of utilizing D-xylose as a sole carbon and energy source were isolated to ferment D-xylose directly to ethanol. Among them, the strain, which showed the best ability to pro-duce ethanol, was selected and was identified as Fusarium sp. The optimal conditions for the pro-duction of ethanol were 8.0 of initial pH, 33$^{\circ}C$ of temperature, and 2% of substrate concentration. Under this optimal condition, the following results were obtained : maximum ethanol concentration, 7.0g/$\ell$; ethanol yield, 0.35g of ethanol per g of D-xylose (68.6% of theoretical); biomass yield, 0.27g of dry biomass per g of D-xylose.

• KSBB Journal
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• v.25 no.4
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• pp.351-356
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• 2010

To increase the production of ethanol by using sugar from lignocellulosic biomass, pentose and hexose have to be fermented simultaneously by yeast. The effects of mixed sugar and nitrogen on ethanol production by immobilized Pichia stipitis KCCM 12009 were investigated. When optimal mixed sugar and nitrogen concentration were 5% (Glucose/Xylose = 3:1) and 1%, respectively, ethanol concentration produced by immobilized P. stipitis was 19-20 g/L. In repeated fed-batch by immobilized P. stipitis, all glucose was consumed very quickly at 1-3% mixed sugar concentration. But, xylose consumption was decreased as the mixed sugar concentration increased. Also, ethanol (5.6 g/L) was stably produced and ethanol production rate was 0.13 g/$L{\cdot}h$ in immobilized cell reactor (ICR) with 1% mixed sugar (Glucose/Xylose = 3:1) as feeding media.

• Journal of Microbiology and Biotechnology
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• v.30 no.8
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• pp.1227-1234
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• 2020

In this study, yeast cell immobilization was carried out in a packed bed reactor (PBR) to investigate the effects of the volumetric capacity of carriers as well as the different fermentation modes on fuel ethanol production. An optimal volumetric capacity of 10 g/l was found to obtain a high cell concentration. The productivity of immobilized cell fermentation was 16% higher than that of suspended-cell fermentation in batch and it reached a higher value of 4.28 g/l/h in repeated batches. Additionally, using this method, the ethanol yield (95.88%) was found to be higher than that of other tested methods due to low concentrations of residual sugars and free cells. Continuous ethanol production using four bioreactors showed a higher productivity (9.57 g/l/h) and yield (96.96%) with an ethanol concentration of 104.65 g/l obtained from 219.42 g/l of initial total sugar at a dilution rate of 0.092 h^-1. Furthermore, we reversed the substrate-feed flow directions in the in-series bioreactors to keep the cells at their highest activity and to extend the length of continuous fermentation. Our study demonstrates an effective method of ethanol production with a new immobilized approach, and that by switching the flow directions, traditional continuous fermentation can be greatly improved, which could have practical and broad implications in industrial applications.

• KSBB Journal
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• v.25 no.2
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• pp.179-186
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• 2010

We investigated the optimal strategy for ethanol production using flocculent Sacchromyces cerevisiae ATCC 96581. Considering the characteristic of flocculent yeast, a repeated fed-batch ethanol fermentation was designed, in which non-sterile glucose powder was fed every 12 hours and, after cell flocculation, new feeding medium was exchanged every 24 or 36 hours. We particularly compared this fermentation process with those when cell flocculation was not carried out. Finally, the maximal total ethanol production was 825 g-ethanol during 120 hours, in which the time interval of withdrawal-fill of feeding medium was 24 hours and cell flocculation was carried out.

• KSBB Journal
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• v.4 no.2
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• pp.172-176
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• 1989

The alcohol fermentation was carried out to study the effect of aeration and unsaturated fatty acids added on the ethanol tolerance of Saccharomyces cerevisiae STV89 and Kluyveromyces fragilis CBS397. The cell growth rate and ethanol production rate was stimulated by aeration and the cell mass production and ethanol production were also substantially improved. With respect to strains, the maximum specific growth rate and overall ethanol productivity of K. fragilis under aerated condition were 6.4 fold and 4.4 fold higher than those of strictly anaerobic condition, although those of S. cerevisiae were increased 1.7 times and 2.3 times by aeration. The addition of ergosterol, linoleic acid and oleic acid also improved the cell growth and ethanol production of S. cerevisiae and K. fragilis. Thus it was found that oxygen and unsaturated fatty acids added played a decisive role on the increase of ethanol tolerance of yeast strains.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.517-521
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• 2009

In this study, the productivity of bio-ethanol obtained from various brown-algae raw materials was examined. Brown-algae polysaccharide, consisting of alginate and laminaran, is usable for the effective production of bio-ethanol if it is hydrolyzed to monomer unit. The objective of this study is the production of bio-ethanol from brown-algae using a heat-treatment and acid-treatment. Bio-ethanol was produced by Saccharomyces cerevisiae KCCM1129 and Pachysolen tannophilus KCTC 7937 strains. Laminaran japonica was higher than Sagassum fulvellum and Hizikia fusiformis, Laminaran japonica optimum pre-treatment is used to derive the ethanol production of Saccharomyces cerevisiae KCCM1129 and Pachysolen tannophilus KCTC 7937 respectively 9.16 g/L, 9.80 g/L. The maximum output of Sargassum fulvellum and Hizikia fusiformis was very low as 0.22 g/L.

• KSBB Journal
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• v.26 no.4
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• pp.317-322
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• 2011

Ulva pertusa is one of the worst pollutant like a waste vinyl after agriculture and caused bad smell at seashore in Jejudo and south area of korean peninsular. For favorable environmental utilization of Ulva pertusa, it could be applied for ethanol production with its acid hydrolysate. The components of hydrolysate included fermentable sugar of glucose, xylose, mannose, galactose, and higher amounts of unfermentable rhamnose. Fermentable sugars were converted to ethanol with S. cerevisiae, also xylose to ethanol with P. stipitis, their maximun ethanol production at optimum conditions were 462 ${\mu}g$/mL and 475 ${\mu}g$/mL, respectively. While, rhamnose cannot be changed to ethanol with S. cerevisiae or P. stipitis, alone. Combination of S. cerevisiae and P. stipitis can convert rhamnose to ethanol, because P.stipitis degradaded rhamnose to pyruvate, and then S. cerevisiae convert to ethanol, at optimum conditions, ethanol reached to 782 ${\mu}g$/mL (30.24%) that is higher than that of 2 strain alone from 500 mg of dried Ulva pertusa contained 2586.45 ${\mu}g$/mL of reduced sugars. Ulva pertusa can be utilized for renewal energy insted of environmenatal enemy.