• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.288-292
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• 1992

Kinetics of anaerobic ethanol fermentation by Clostridium thermohydrosulfuricum were investigated for the one-step production of ethanol from starch. A mutant strain with a high ethanol yield was induced from C. thermohydrosulfuricum. The mutant, designated as ME4, produced anaerobically 6.1 g/l of ethanol, 3.1 g/l of lactate and 0.1 g/l of acetate from 20 g/l of starch at $68^{\circ}C.

• Microbiology and Biotechnology Letters
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• v.17 no.1
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• pp.14-18
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• 1989

As the final experiment to assess the possibility of industrial application of FSC14-75, ethanol productivity from liquefied sweet potato starch was examined in a pilot scale of 300 liters. FSC14-75 produced 6.6％(v/v) of ethanol from 13.3％ of liquefied sweet potato starch in 8 days, and the residual sugar was 3.15％. The corresponding efficiency was 70％ of the theoretical maximum. Since we could isolate unicellular cell and flocculent cell from the fermentation broth, we designated them FSC14-75(S) and FSC14-75(F), respectively. We investigated ethanol productivity of FSC14-75(F) compared with that of FSC14-75(S) from liquefied potato starch in a mini·tar tormentor scale of 2.5 liters. FSC14-75(F) was found more favorable than the counterpart in terms of ethanol productivity, and produced 8.1％(v/v) of ethanol from 15％ of liquefied potato starch with an efficiency of 75％. In a pilot scale fermentation with 15％ of liquefied sweet potato starch, ethanol productivity of FSC14-75(F) reached maximum level of 7.7％(v/v) after 8 days, and the residual sugar was 1.9％. However, the ethanol productivity was not enhanced by a supplementary addition of Thermamyl to the fermentation broth after sterilization.

• Microbiology and Biotechnology Letters
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• v.24 no.6
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• pp.726-732
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• 1996

To improve the fermentation characteristics(such as starch-degradability, ethanol tolerance, sugar and high-temperature tolerance) of recombinant haploid yeast Saccharomyces diastaticus K114, hybridization technique was used. The hybridization partner was S. diastaticus 1177 which had good glucoamylase activity and fermentabi- lity. The best hybrid HH64 showed improved ethanol tolerance, sugar and high-temperature tolerance. Especia- lly, the starch-fermentability was significantly improved, since the hybrid produced 1.60% (w/v) ethanol from 4% (w/v) starch, while the recombinant haploid K114 produced 1.30% (w/v) ethanol. The optimum temperature and pH for the starch-fermentation by the hybrid HH64 was 30$\circ$C and 5, respectively. The hybrid yeast HH64 produced 7.5% (w/v) ethanol directly from 20% (w/v) starch.

• Microbiology and Biotechnology Letters
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• v.11 no.3
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• pp.181-185
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• 1983

The possibility of the ethanol fermentation from raw cassava starch without cooking was investigated. Saccharification yield in the simultaneous saccharification-fermentation (SSF) system was compared with that in saccharification of raw cassava starch, using glucoamylase of Aspergillus shirousmi. Although the saccharification yield of raw cassava starch with 10 folds of the enzyme was 60% compared to cooked cassava starch, higher saccharification could be obtained by SSF This result is maybe due to the elimination of end product inhibition in saccharification of raw starch by glucoamylase. Final ethanol yield from raw cassava starch was about 88% under the condition of 3$0^{\circ}C$, 120 rpm shaking after 3 days in the SSF system.

• KSBB Journal
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• v.7 no.3
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• pp.229-234
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• 1992

Alcohol fermentations were carried out to confirm the capacity of ethanol production from glucose, starch and soluble starch(dextrin) by Schwanniomyces castellii NRRL Y-2477. Schw. castellii NRRL Y-2477 was able to produce the 63.9g/l ethanol using 94% subtrate from 150g/l-glucose medium. The direct alcohol fermentation of starch having the maximum solubility of 20g/1 at $30^{\circ}C$ yielded 9.1g/l ethanol upon complete depletion of starch, whereas 34.5g/1 ethanol was produced by utilizing 82% of 100g/1 soluble starch medium. The fermentation of 150g/1 soluble starch produced 52.1g/l ethanol using about 79% of substrate. Thus, it was found that the limiting step of direct alcohol fermentation of starch by Schwanniomyces castellii NRRL Y-2477 was a hydrolysis of starch.

• Microbiology and Biotechnology Letters
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• v.17 no.1
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• pp.8-13
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• 1989

The optimum conditions for ethanol fermentation and ethanol productivity of the fusant ESC-14-15 were examined in a mini-jar formentor scale (working volume : 2.5 liters) to assess the possibility of practical application. Addition of yeast extract to fermentation broth greatly enhanced the ethanol productivity and shortened the period of fermentation. The pH 4.2 was more favorable than pH 5.5 with respect to ethanol productivity and fermentation speed. The optimum concentration of liquefied potato starch for ethanol fermentation of FSC-14-15 was 15%(w/v) and the corresponding productivity was 8.7%(v/v) of ethanol with an efficiency of 80.6% to the theoretical maximum. When the fresh fermentation broth containing 20% of liquefied potato starch was inoculated with love(v/v) of inoculum, the fusant FSC-14-75 produced 11.0%(v/v) of ethanol in 4 days, which is considered comparable to that from an industrial process. From the liquefied cassava starch or the equal mixture of liquefied barley and sweet potato starch prepared according to the same method as in the industrial process except saccharification step, the fusnnt FSC-14-75 produced 8.5%(v/v) or 7.6%(v/v) of ethanol in 4 days, respectively.

• Journal of Microbiology and Biotechnology
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• v.19 no.10
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• pp.1161-1168
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• 2009

Ethanol production by the simultaneous saccharification and fermentation (SSF) of low-value rice wine cake (RWC) without cooking was investigated. RWC is the filtered solid waste of fermented rice wine mash and contains 53% raw starch. For the SSF, the RWC slurry was mixed with the raw-starch-digesting enzyme of Rhizopus sp. and yeast, where the yeast strain was selected from 300 strains and identified as Saccharomyces cerevisiae KV25. The highest efficiency (94%) of ethanol production was achieved when the uncooked RWC slurry contained 23.03% starch. The optimal SSF conditions were determined as 1.125 units of the raw-starch-digesting enzyme per gram of RWC, a fermentation temperature of $30^{\circ}C$, slurry pH of 4.5, 36-h-old seeding culture, initial yeast cell number of $2{\times}10^7$ per ml of slurry, 17 mM of urea as the nitrogen additive, 0.25 mM of $Cu^{2+}$ as the metal ion additive, and a fermentation time of 90 h. Under these optimal conditions, the ethanol production resulting from the SSF of the uncooked RWC slurry was improved to 16.8% (v/v) from 15.1% (v/v) of pre-optimization.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.858-862
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• 2008

The Simultaneous Saccharification and Fermentation(SSF) of ethanol production from potato starch studied with respect to growth pH, temperature, substrate concentration. The glucoamylase and Saccharomyceses cerevisiae have a capacity to carry out a single stage SSF process for ethanol production. The characteristics, termed as starch hydrolysis, accumulation of glucose, ethanol production and biomass formation, were affected with variation in pH, temperature and starch concentration. The maximum ethanol concentration of 12.9g/l was obtained using a starch concentration 30g/l, which represent an ethanol yield of 86%. The optimum conditions for the maximum ethanol yield were found to be a temperature of 38, pH of 4.0 and fermentation time of 18hr. Thus by using the control composite design, it is possible to determine the accurate values of the fermentation parameters where maximum production of ethanol occurs.

• Microbiology and Biotechnology Letters
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• v.12 no.4
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• pp.261-264
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• 1984

The optimal condition of the ethanol fermentation from raw cassava starch by simultaneous saccharification - fermentation (SSF) was studied using glucoamylase from Aspergillus sp. and a yeast strain. The rate and yield of ethanol production were optimum at pH 3.6 with shaking. The fine milling treatment was effective for both saccharification and SSF of raw cassava starch. The presaccharification at 6$0^{\circ}C$ for 1 hr before SSF increased the rate and yield of ethanol production, as well. To increase the ethanol concentration after fermentation the substrate concentration could be increased up to 2195 without the problem of viscosity. The use of high concentration ethanol tolerant yeast strains and high substrate concentration produced ethanol higher than 10%(W/V) after fermentation for 5 days.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.604-612
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• 1996

To improve the fermentation characteristics of the haploid starch-fermenting recombinant yeast strain K114/YIpMS$\Delta$R(LEU2/URA3) secreting both $\alpha$-amylase and glucoamylase was rare-mated with polyploid industrial yeast Saccharomyces sp. K35. The K35 strain had good fermentation-characteristics such as ethanol-tolerance, high temperature and sugar-tolerance, and high fermentation rate. Among the resulting 66 hybrids, the best strain RH51 was selected. The RH51 exhibited amylolytic activity of K114/YIpMS$\Delta$R(LEU2/URA3) as well as ethanol and sugar tolerance of K35. The optimum temperature of hybrid RH51 for starch fermentation was 34$\circ$C which was same as that of K35 but different from that (30$\circ$C) of K114/YIpMS$\Delta$R(LEU2/URA3). The optimum pH was 5.0. The optimum size of inoculum was 2% as the pellet (w/v) of yeast cells. The hybrid strain RH51 produced 7.0% ethanol (w/v) from 20% (w/v) soluble starch while K35 formed almost no ethanol, 0.3% (w/v). RH51 strain produced 7.5% (w/v) ethanol after 8 days in a 2.5 l fermenter containing 800 ml of 20% (w/v) soluble starch. The residual starch content in the fermentation medium was 1.68% (w/v), and therefore almost all the starch was fermented completely.