• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1245-1253
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• 2014

One-step sulfuric acid saccharification of the red alga Pterocladiella capillacea was optimized, and various detoxification methods (neutralization, overliming, and electrodialysis) of the acid hydrolysate were evaluated for fermentation with the thermotolerant yeast Kluyveromyces marxianus. A proximate composition analysis indicated that P. capillacea was rich in carbohydrates. A significant galactose recovery of $81.1{\pm}5%$ was also achieved under the conditions of a 12% (w/v) biomass load, 5% (v/v) sulfuric acid, $121^{\circ}C$, and hydrolysis for 30 min. Among the various detoxification methods, electrodialysis was identified as the most suitable for fermentable sugar recovery and organic acid removal (100% reduction of formic and levulinic acids), even though it failed to reduce the amount of the inhibitor 5-HMF. As a result, K. marxianus fermentation with the electrodialyzed acid hydrolysate of P. capillacea resulted in the best ethanol levels and fermentation efficiency.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.530-535
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• 2019

Diverse types of nuruks (traditional Korean fermentation initiators) were examined in order to isolate thermotolerant yeast strains capable of utilizing xylose as a carbon source. Among twenty yeast strains that grew at 46℃, MBY/L1597 showed a notably higher specific growth rate than other strains. This strain was identified as Millerozyma farinosa. While the control strain M. farinosa KCTC27412 (= CBS7064) did not show xylose reductase (XR) activity and apparent growth at 46℃, M. farinosa MBY/L1597 exhibited XR activity of 4.98 ± 0.49 U/mg protein when NADPH was used as a cofactor. M. farinosa MBY/L1597 cultured at 46℃ produced (9.87 ± 1.00 g/l) xylitol from 20 g/l xylose, corresponding to approximately 50% yield. M. farinosa MBY/L1597 was deposited at the Korean Collection for Type Cultures as KCTC27797.

• Journal of Microbiology and Biotechnology
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• v.5 no.2
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• pp.114-116
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• 1995

Concentrated Brazillian sugar cane stillage was used as a substrate for the yeast biomass production using Candida rugosa isolated from East Africa. At the optimum stillage concentration of 10% dry matter, biomass production was 20.4 g/l and COD reduction rate was 41%. The specific growth rate of the yeast was 0.17 $h^{-1}$ and the corresponding productivity 0.91 g $l{-1} h^{-1}$ in the batch fermentation was observed at $40{\circ}^C$.

• Journal of Life Science
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• v.16 no.3 s.76
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• pp.454-458
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• 2006

HSF1 is the heat shock transcription factor in Saccharomyces cerevisiae. S. cerevisiae KNU5377 can ferment at high temperature such as $40^{\b{o}}C$. We have been the subjects of intense study because Hsf1p mediates gene expression not only to heat shock, but to a variety of cellular and environmental stress challenges. Basing these facts, we firstly tried to construct the hsf1 gene-deleted mutant. PCR-method for fast production of gene disruption cassette was introduced in a thermotolerant yeast S. cerevisiae KNU5377, which allowed the addition of short flanking homology region as short as 45 bp suffice to mediate homologous recombination to kanMX module. Such a cassette is composed of linking genomic DNA of target gene to the selectable marker kanMX4 that confers geneticin (G418) resistance in yeast. That module is extensively used for PCR-based gene replacement of target gene in the laboratory strains. We describe here the generation of hsf1 gene disruption construction using PCR product of selectable marker with primers that provide homology to the hsf1 gene following separation of haploid strain in wild type yeast S. cerevisiae KNU5377. Yeast deletion overview containing replace cassette module, deletion mutant construction and strain confirmation in this study used Saccharomyces Genome Deletion Project (http:://www-sequence.standard.edu/group/yeast_deletion_project). This mutant by genetic manipulation of wild type yeast KNU5377 strain will provide a good system for analyzing the research of the molecular biology underlying their physiology and metabolic process under fermentation and improvement of their fermentative properties.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.7
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• pp.1011-1014
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• 2003

The objective of this work was to evaluate a thermotolerant yeast Issatchenkia orientalis DY252 as a microbial feed additive for ruminants. In the present study, the influence of volatile fatty acids (VFA) and temperature on oxygen uptake rate by I. orientalis DY 252 was investigated. It was evident that the oxygen uptake rate was decreased gradually as the VFA concentrations increased in a range of 30 to 120 mM. Although the oxygen uptake rate was not greatly affected by temperature in the range 37 to $43^{\circ}C$, a maximum value of $0.45mg\;O_2/g$ cell/ min was obtained at $39^{\circ}C$. With regard to the oxygen uptake rate by yeast, viability was found to be less important than the metabolic activity of yeast.

• Proceedings of the Korean Society of Life Science Conference
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• 2005.04a
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• pp.138-138
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• 2005

• Proceedings of the Korean Society of Life Science Conference
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• 2005.04a
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• pp.238-238
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• 2005

• Journal of the Korea Organic Resources Recycling Association
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• v.12 no.3
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• pp.119-125
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• 2004

Sugar beet stillages were used as a substrate for the production of single cell protein by a thermotolerant yeast Candida rugosa. 3 Stillage substrates were nutritionally optimized for the better production of yeast biomass and for the reduction of COD. The addition of Phosphorus(P) was required for all stillages, but Nitrogen(N) only when the residual sugar remained. The addition of P increased the biomass production to 23-61%. The addition of N increased the biomass production only a little, but when added together with P increased to 90%. The COD decreased to 26-46% when P was added, but decreased to 85% when P was added together with N.

• Microbiology and Biotechnology Letters
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• v.25 no.5
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• pp.435-441
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• 1997

Forty seven strains of yeast were isolated from traditional Meju and were identified as Saccharomyces spp. (7 strains), Zygosaccharomyces spp. (7 strains), Kluyveromyces spp. and Hansenula spp. (each 5 strains), Rhodotorular spp. (8 strains), Candida spp. (12 strains), Pichia spp. and Debaryomyces spp. from results of their microbiological characteristics. The optimal medium for growth of all the yeasts was YM media and the optimal initial pH of the medium was 6.0. The optimum temperature for growth was 30$circ$ and among them, Sacch. exiguus OE-5, Sacch. cerevisiae OE-16, Sacch. kluyveri C-1 strains were thermotolerant yeasts which could grow at 40$circ$C.

• KSBB Journal
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• v.25 no.6
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• pp.565-571
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• 2010

To develop thermostable ethanol fermentative yeast strain for lignocellulosic simultaneous saccharification and fermentation, high ethanol producing yeast, Saccharomyces cerevisiae CHY1012 and thermostable yeast, Kluyveromyces marxianus CHY1703 were fused by protoplast fusion. The thermostable fusant, CHY1612 was identified as a Kluyveromyces marxianus by phenotypic and physiological characteristics, as well as molecular analysis based on the D1/D2 domains of the large subunit (26S) rDNA gene and the internally transcribed spacer (ITS) 1 + 2 regions. For lignocellulosic ethanol production, AFEX pretreated barley straw at $150^{\circ}C$ for 90 min was used in a simultaneous saccharification and fermentation (SSF) process using thermotolerant CHY1612. The SSF from 16% pretreated barley straw at $43^{\circ}C$ gave a saccharification ratio of 90.5%, a final ethanol concentration of 38.5 g/L, and a theoretical yield of 91.2%. These results show that K. marxianus CHY1612 has potential for lignocellulosic ethanol production through simultaneous saccharification and fermentation with further development of process.