• Applied Biological Chemistry
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• v.28 no.1
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• pp.36-47
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• 1985

$HIS_5$ gene of Saccaromyces cerevisiae was cloned into pBR 322 and also into pSH 610 shuttle vector. $HIS_5$ gene was expressed as promoter of lactose operon(lacZ). And $HIS_5-lacZ$ fusion was intergrated into chromosome III of yeast. $HIS_5$ gene in yeast growth was controlled general amino acid control mechanism.

• Mycobiology
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• v.38 no.4
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• pp.302-309
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• 2010

Formic acid is a representative carboxylic acid that inhibits bacterial cell growth, and thus it is generally considered to constitute an obstacle to the reuse of renewable biomass. In this study, Saccharomyces cerevisiae was used to elucidate changes in protein levels in response to formic acid. Fifty-seven differentially expressed proteins in response to formic acid toxicity in S. cerevisiae were identified by 1D-PAGE and nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS) analyses. Among the 28 proteins increased in expression, four were involved in the MAP kinase signal transduction pathway and one in the oxidative stress-induced pathway. A dramatic increase was observed in the number of ion transporters related to maintenance of acid-base balance. Regarding the 29 proteins decreased in expression, they were found to participate in transcription during cell division. Heat shock protein 70, glutathione reductase, and cytochrome c oxidase were measured by LC-MS/MS analysis. Taken together, the inhibitory action of formic acid on S. cerevisiae cells might disrupt the acidbase balance across the cell membrane and generate oxidative stress, leading to repressed cell division and death. S. cerevisiae also induced expression of ion transporters, which may be required to maintain the acid-base balance when yeast cells are exposed to high concentrations of formic acid in growth medium.

• Molecules and Cells
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• v.28 no.4
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• pp.369-373
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• 2009

Heterologous secretory expression of endoglucanase E (Clostridium thermocellum) and ${\beta}$-glucosidase 1 (Saccharomycopsis fibuligera) was achieved in Saccharomyces cerevisiae fermentation cultures as an ${\alpha}$-mating factor signal peptide fusion, based on the native enzyme coding sequence. Ethanol production depends on simultaneous saccharification of cellulose to glucose and fermentation of glucose to ethanol by a recombinant yeast strain as a microbial biocatalyst. Recombinant yeast strain expressing endoglucanase and ${\beta}$-glucosidase was able to produce ethanol from ${\beta}$-glucan, CMC and acid swollen cellulose. This indicates that the resultant yeast strain of this study acts efficiently as a whole cell biocatalyst.

• Korean Journal of Medicinal Crop Science
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• v.28 no.5
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• pp.371-378
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• 2020

Background: In this study, the radix of Astragalus membranaceus Bunge extract fermented by Saccharomyces cerevisiae, Weissella cibaria, and Pediococcus pentosaceus to increase the levels of isoflavonoid aglycone contents. Methods and Results: In order to change the in isoflavonoids, we fermented the radix of A. membranaceus extracts with microorganisms that have β-glucosidase activity. Besed on the β-glucosidase activity, we selected three strains, Weissella cibaria, Pediococcus pentosaceus, and Saccharomyces cerevisiae. HPLC analysis revealed that the levels of isoflavonoid aglycones were increased in all fermentation cases, and the extracts fermented by S. cerevisiae showed the highest levels of isoflavonoid aglycones. We evaluated the antioxidant activity, anti-wrinkle effects and whitening effects of the S. cerevisiae-fermented extracts using the DPPH assay, tyrosinase inhibition activity assay, and collagenase inhibition activity assay. We confirmed higher activity in S. cerevisiae-fermented extracts than in control, with the half maximal inhibitory concentration (IC₅₀) value of 565.1 ± 59.1 ㎍/㎖ in DPPH radical scavenging activity, tyrosinase inhibition rate of 78.4 ± 0.9%, and collagenase inhibition rate of 83.8 ± 1.1%. Conclusions: We selected three stains of microorganisms showing high β-glucosidase activity, W. cibaria, P. pentosaceus and S. cerevisiae. Isoflavonoid glycones in the radix of A. membranaceus were converted to isoflavonoid aglycones by fermentation. In addition, the fermented radix of A. membranaceus exhibited antioxidant activity, anti-wrinkle effect, whitening effect and radical scavenging activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.794-800
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• 1999

This study was carried out to obtain the basic information for improving the flavor quality of yakju. Three kinds of yakju were prepared with different yeast strains to investigate the effects of those strains on flavor components. A total of 23 strains were isolated from fruits such as apple, pear, persimmon and citron and two strains were excellent in producing ethanol and flavors. They were identified as Saccharomyces cerevisiae S 2 and Saccharomyces cerevisiae S 6 from morphological cultural test and physiological quality. Yakju A, B and C were prepared with S 2, S 6 and Saccharomyces cerevisiae IFO 1950, respectively. Flavor components of yakju were analyzed by gas chromatography and mass spectr ometry. A total of 57 peaks were detected and 13 compound were identified. They were 4 alcohol, 2 esters, 7 acids and miscellaneous compounds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.2
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• pp.348-352
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• 1999

We have intended to accelerate the secretion of human lysozyme(HLY) with permeabilizing agents from the cultivated cells of the recombinant Saccharomyces cerevisiae. The five agents CaCl2, Tween 80, ethanol, Triton X 100, and cetyltrimethylammonium bromide(CTAB) were used as permeabilizing agents. Treatments of the yeast cell with CaCl2, Tween 80, and ethanol were effective to increase the secretion from the yeast cells. Especially, treatment of 10% ethanol increased the extracellular HLY activity by 38.6% at 30oC for 48 h in culture broth. But Triton X 100 and CTAB unexpectedly didn't play a role in increase of HLY secretion. Recovery of a foreign protein by permeabilizing agents is easier than by osmotic shock, and is less expensive than enzymatic digestion.

• KSBB Journal
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• v.28 no.6
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• pp.366-371
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• 2013

Ethanol productions were performed by separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes using seaweed, Enteromorpha intestinalis (sea lettuce). Pretreatment conditions were optimized by the performing thermal acid hydrolysis and enzymatic hydrolysis for the increase of ethanol yield. The pretreatment by thermal acid hydrolysis was carried out with different sulfuric acid concentrations in the range of 25 mM to 75 mM $H_2SO_4$, pretreatment time from 30 to 90 minutes and solid contents of seaweed powder in the range of 10~16% (w/v). Optimal pretreatment conditions were determined as 75 mM $H_2SO_4$ and 13% (w/v) slurry at $121^{\circ}C$ for 60 min. For the further saccharification, enzymatic hydrolysis was performed by the addition of commercial enzymes, Celluclast 1.5 L and Viscozyme L, after the neutralization. A maximum reducing sugar concentration of 40.4 g/L was obtained with 73% of theoretical yield from total carbohydrate. The ethanol concentration of 8.6 g/L of SHF process and 7.6 g/L of SSF process were obtained by the yeast, Saccharomyces cerevisiae KCTC 1126, with the inoculation cell density of 0.2 g dcw/L.

• Microbiology and Biotechnology Letters
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• v.25 no.3
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• pp.258-265
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• 1997

The effects of medium pH and culture temperature on the expression and secretion of inulinase and invertase were investigated with recombinant Saccharomyces cerevisiae cells. These cells were obtained by transformation of 2$\mu$-based plasmids pYI10 and pYS10 which contain Kluyveromyces marxianus inulinase gene (INU1A) and S. cerevisiae invertase gene (SUC2), respectively, in the downstream of GAL1 promoter. The expression level and localization of inulinase and invertase were not affected significantly by the initial medium pH: secretion efficiencies of inulinase and invertase into the medium were about 90% and 60%, respectively, in the pH ranges of 4.0 to 6.5. However, the expression and secretion of both enzymes were strongly dependent on the culture temperature. The highest expression (7.7 units/mL) and secretion (6.7 units/mL) of inulinase were observed at 28$\circ$C and 30$\circ$C. As a consequence of decreased localization of inulinase in the periplasmic space, the secretion efficiency increased from 68% at 20$\circ$C, to 95% at 35$\circ$C,. The total expression level and secretion efficiency of invertase increased from 19 units/mL and 55% at 20$\circ$C to 25 units/mL and 68% at 35$\circ$C, respectively. Irrespective of the culture temperature, the invertase activity in the cellular fraction (periplasmic space and cytoplasmic fractions) was kept constant at around 33-45%.

• Korean Journal of Microbiology
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• v.37 no.1
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• pp.28-36
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• 2001

These studies were carried out to understand the mechanisms of genes which are related in cell cycle progression at G1/S phase. Mutants involved in cell cycle progression and regulation in Saccharomyces cerevisiae were isolated and characterized. To isolate new mutants, we screened the sensitivity to ciclopirox olamine (CPO) which inhibits the cell cycle traverse at or very near the G1/S phase boundary in HeLa cell and budding yeast. As results, we isolated 30 mutants and named cos(ciclopirox olamine sensitivity: cos27∼cos57) mutants. To determine the phenotype of mutants, we examined the sensitivity to methyl-methane sulfonate (MMS) and hydroxyurea (HU). Several mutants were sensitive to MMS and HU. According to these Phenotypes, cos mutants were grouped into four. Group I mutants are cos27, cos28, cos32, cos33, cos36, cos37, cos40, cos42, cos46, cos50, cos52 and cos53 which show MMS, HU sensitivities and might act at a checkpoint pathway during S phase. Group II mutants are cos43 and cos48 which show MMS sensitivities and might act at a checkpoint pathway during Gl or G2 phase. Group III mutants are cos35, cos47, cos54, cos55 and cos56 which show HU sensitivities and might act at a progress pathway during S phase. Finally, Group IV mutants are cos29, cos30, cos31, cos34, cos38, cos39, cos41, cos44, cos45, cos49, cos51 and cos57 which show only CPO sensitivities. Moreover, we examined the terminal phenotype of mutants under fluorescent microscope and then found one of S phase checkpoint related mutant(cos37). Furthermore, we constructed the heterozygote strain between mutant and wild type haploid strains to study their genetic analysis of cos mutants.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.253-259
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• 1996

To investigate the yeast florae in the traditional and commercial Kochujang, computer identification systems, Vitek, API kit and conventional identification methods were used. Yeast florae of each process were compared and their typical physiological characteristics were also tested. Various process intervals yielded 330 colonies, which resulted in 11 species 184 strains classified. They were identified into Candida glabrata C. guilliermondii. C. humicola. C. rugosa, C. zeylanoides, Cryptococcus uniguttulatus, Pichia farinosa, Rhodotorula glutinis, Saccharomyces cerevisiae and Zygosaccharomyces rouxii. The strains of Candida, Pichia, Saccharomyces and Zygosaccharomyces were existing in both processes. In case of commercial process, the maximum distribution of Z. rouxii and S. cerevisiae were 33% at 15 day fermentation and 13% at 21 day, respectively. The distribution of Candida spp. was gradually decreased throughtout the fermentation period from 40% to 10%. In the traditional process, the maximum distribution of Z. rouxii and S. cerevisiae were 53% after 3 months and 26% after 7 months, respectively, S. cerevisiae and Z. rouxii showed distintive growth pattern at the high concentration of glucose and sodium chloride and played important roles in both processes of fermentation. Physiological tests revealed that only two major yeasts. S. cerevisiae and Z. rouxii, showed vigorous carbon dioxide formation under the tested conditions.