• Journal of Life Science
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• v.29 no.3
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• pp.376-381
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• 2019

To construct useful yeast strain for bioethanol production, we improved yeast harboring various phenotypes by using yeast protoplast fusion method. In this study, S. cerevisiae BYK-F11 strain which have ethanol tolerance, thermotolerance and ${\beta}-glucanase$ activity and P. $stipitis{\Delta}ura$ strain which has xylose metabolism pathway were fused by genome shuffling. P. $stipitis{\Delta}ura$ strain was constructed for protoplast fusion by URA3 gene disruption, resulting in uracil auxotroph. By protoplast fusion, several fused cells were selected and BYKPS-F8 strain (fused cell) showing both karyotypes from two parent strains (S. cerevisiae BYK-F11 and P. $stipitis{\Delta}ura$ strain) among 22 fused cells was finally selected. Sequentially, various phenotypes such as ${\beta}-glucanase$ activity, xylose utility, ethanol tolerance, thermotolerance and ethanol productivity were analyzed. The BYKPS-F8 strain obtained ${\beta}-glucanase$ activity from BYK-F11 strain and 1.2 fold increased xylose utility from P. $stipitis{\Delta}ura$ strain. Also, the BYKPS-F8 strain showed thermotolerance at $40^{\circ}C$ and increased ethanol tolerance in medium containing 8% ethanol. In this fused cell, 7.5 g/l ethanol from 20 g/l xylose was produced and the multiple phenotypes were stably remained during long term cultivation (260 hr). It was proved that novel biological system (yeast strains) is easily and efficiently bred by protoplast fusion among yeasts having different genus.

• Food Science and Preservation
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• v.18 no.4
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• pp.604-611
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• 2011

Several wild yeasts were isolated from Korean grape varieties before and during spontaneous fermentation. Among them, four strains were isolated based on the alcohol content and flavor production in wine after fermentation of apple juice. In this study, the four yeast strains were identified and characterized. PCR-restriction fragment length polymorphism analysis of ITS I-5.8S-ITS II region with restriction endonuclease Hae III and Hinf I resulted in that all the strains showed a typical pattern of Saccharomyces cerevisiae. Pulse field gel electrophoresis showed three different chromosome patterns with a same band between strains SS89 and SS812. When ITS I-5.8S-ITS II sequences of the four strains were compared with one another, they were similar to those of Saccharomyces cerevisiae CBS 4054 type strain. Identity of the sequences was higher than 97% with those of the type strain. Phylogenetic analysis showed based on the sequences showed they were genetically closed to the type strain. The four identified strains were tested in a medium containing 200 ppm potassium metabisulfite, and the MM10 and WW108 inhibition rates resulted at up to 24 h. The four strains were tested at an incubation temperature of $30^{\circ}C$. The 30% sugar concentration in the medium (w/v) showed the highest growth in 36 h, especially in the case of SS89, which was close to growth 40. The four strains were tested in an 8% ethanol medium (v/v). Alcohol tolerance was initially kept in the incubation process. The strains began to adapt, however, to the exceeded resistance. The four strains showed the lowest inhibition rate at 24 h.

• Journal of Microbiology and Biotechnology
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• v.25 no.5
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• pp.718-722
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• 2015

Techniques for immobilizing effective enzymes on nanoparticles for stabilization of the activity of free enzymes have been developing as a pharmaceutical field. In this study, we examined the effect of three different pH conditions of phosphate buffer, as a dissolving solvent for lysosomal enzymes, on the direct immobilization of lysosomal enzymes extracted from Hen's egg white and Saccharomyces cerevisiae. Titanium(IV) oxide (TiO₂) nanoparticles, which are extensively used in many research fields, were used in this study. The lysosomal enzymes immobilized on TiO₂ under each pH condition were evaluated to maintain the specific activity of lysosomal enzymes, so that we can determine the degree of melanin treatment in lysosomal enzymes immobilized on TiO₂. We found that the immobilization efficiency and melanin treatment activity in both lysosomal enzymes extracted from Hen's egg white and S. cerevisiae were the highest in an acidic condition of phosphate buffer (pH 4). However, the immobilization efficiency and melanin treatment activity were inversely proportional to the increase in pH under alkaline conditions. In addition, enhanced immobilization efficiency was shown in TiO₂ pretreated with a divalent, positively charged ion, Ca²⁺, and the melanin treatment activity of immobilized lysosomal enzymes on TiO₂ pretreated with Ca²⁺ was also increased. Therefore, this result suggests that the immobilization efficiency and melanin treatment activity of lysosomal enzymes can be enhanced according to the pH conditions of the dissolving solvent.

• Korean Journal of Microbiology
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• v.40 no.2
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• pp.178-182
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• 2004

In the vegetative hyphae of Aspergillus nidulans, a zymogenic form of the class I chitin synthase activity was successfully measured by the assay condition for Saccharomyces cerevisiae class I chitin synthase, Chsl. The class I chitin synthase activity of the A. nidulans chsC wild type strain was increased about six-fold by trypsin-pretreatment, but that of the chsC disruption strain revealed no increase. Interestingly enough, level of the class I chitin synthase activity of the chsC disruption strain was almost the same as that of the chsC wild type without trypsin-pretreatment. These results indicated that the A. nidulans ChsC activity could be measured by account-ing the class I chitin synthase activity without the trypsin-pretreatment as an internal control. Consistence to the expression pattern of the chsC revealed by northern blot analysis, the activity of ChsC was increased upon reaching the culture time for acquiring developmental competence. Our results shown here also supported the previous report suggesting the possible involvement of ChsC in vegetative hyphal growth of A. nidulans.

• Journal of Life Science
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• v.13 no.5
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• pp.604-617
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• 2003

Candida albicans is one of the most common etiological agents in fungi-associated skin infections. There is an increase of candidiosis especially in the patient of acquired or induced immunodeficiency syndromes or in the event of long-term antibiotics and immuno-suppressor or cytotoxic therapies. To screen out reliable and effective anti-candidiosis agent, in this study, we have evaluated antifungal activity of 298 plant extracts against C. albicans. Based on the results of disc-paper method and determination of minimal inhibitory concentration, fifteen extracts were finally selected as possible sources of anti-candidiosis agent. Especially, six different plant extracts, such as Rubus parvifolius, Euphorbia pekinensis, Coptis chinensis, Eugenia aromaticum, Paeonia lactiflora var. hortensis and Paeonia suffruticosa showed strong antifungal activity against C. albicans, not to S. cerevisiae. These results suggested that medicinal and wild plants could be the potential source of antifungal agent.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.4
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• pp.342-347
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• 1988

This studies were carried out to investigated the effects of starter on the fermentation of Kimchi. The organisms isolated from Kimchi, Lactobacillus plantarum, Lactobacillus brevis, Pediococcus cerevisiae and Leuconostoc mesenteroides, were used as starter for preparation of Kimchi. The fermentation of starter inoculated Kimchi was enhanced compared with that of starter not inoculated Kimchi at $25^{\circ}C$. The mixed strain was more effective than single strain on the fermentation Kimchi. The fermentation of starter incoculated Kimchi was enhanced by addition of red pepper, whereas inhibited during first days by addition of Singer. The fermentation period of starter inoculated Kimchi was shortened about 24hours compared with that of starter not inoculated Kimchi at $25^{\circ}C$. The sensory score of starter inoculated Kimchi was better than that of starter not inoculated Kimchi in odor, flavor and overall acceptability. The effect of starter was significant in odor of Kimchi.

• Korean Journal of Microbiology
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• v.38 no.2
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• pp.96-102
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• 2002

The S-phase checkpoint mechanisms response to DNA damage or inhibition of DNA replication for maintenance of genetic stability in eukaryotic cells. These roles include cell cycle control arrest at S-phase and Iranscriptional induction of repair genes. To characterize the defects of dpbll mutant for both these responses, we examined the over-expression effect of DPBll gene, the sensitivity to HU, MMS, and the transcriptional pattern by DNA damage agent for RNRS mRNA. RNRS transcript is induced in response to a wide variety of agents that either damage D7A directly through chemical modification or induce stress by blocking DNA synthesis. As results, dpbll-1 cells are sensitive to DNA damage agents and the level of RNR3 mRNA is reduced approximately 40% than wild type cells. Moreover, we found the same results in dpb2-1 cells. Therefore, we propose that DPB2 and DPBll act as a sensor of replication that coordinates the transcriptional and cell cycle responses to replication blocks.

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.225.3-225
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• 2005

• YAKHAK HOEJI
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• v.35 no.4
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• pp.308-313
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• 1991

The synthesis of 1-[(2-phenyl-1, 3-benzodioxol-2-yl)methyl]-1H-imidazole derivatives is described starting with 2-bromoacetophenones and catechols. 1-[(2-Phenyl-1, 3-benzodioxol-2-yl)methyl]-1H-imidazole (9-$_{12}$) showed potent broad-spectrum activity, not only against Candida species but also Cr. neofortnans, S. cerevisiae and T. mentagrophytes.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.77-77
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• 2003

Gene expression in a cell is regulated by mutual activations or repressions between genes. Identifying the gene regulation network will be one of the most important research topics in the post genomic era. We propose a linear dynamic model of gene regulation for the yeast cell cycle. A small gene network consisting of about 40 genes is reconstructed from the analysis of micro-array gene expression data of yeast S. cerevisiae published by P. Spellman et al. We show that the network construction is consistent with the result of the hierarchical cluster analysis.