• Preventive Nutrition and Food Science
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• v.1 no.2
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• pp.252-255
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• 1996

As an index of freeze-injury of yeast, the leakage of intracellular substances from yeast cells after freeze-thawing was investigated. It was found that much more ultraviolet-absorbing substances leaked out from non-freeze tolerant yeast (NETY) than from freeze-tolerant yeast. Furthermore, the rate of leakage of cellular substances form NFTY during incubation exceeded that of FTY, indicating that NFTY is more susceptible to freeze-injury than FTY during frozen-storage. An apparent degradation of phospholipid was observed during incubation of perfermented frozen-cells of NFTY, while little change of phospholipid occurred in FTY, These results suggested that the difference in the sensitivity of yeast might be due to the strength of cell membrane in terms of the degradation of phospholipid by enzymes, phospholipases, attached to cell membranes.

• Korean Journal of Poultry Science
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• v.24 no.2
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• pp.67-72
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• 1997

In order to investigate the effect of feeding live yeast (Sacckaromyces cerevisiae) on the growth performance and changes of intestinal microorganism (E. coli), a growth assay was conducted with 144 broiler chicks. Treatments were consisted of corn-soybean meal control, 0.05% live yeast, and 0.05% dead yeast. Most of the chick protein of the live yeast was in the pure protein form, and had a high amino acid composition with 47% of essential amino acids and 53% of non-essential amino acids. No differences in growth performance were shown among dietany treatments. Total number of E. coli in the small intestine of chicks fed either live or dead yeast was significantly reduced compared to chicks fed the control diet. Although the changes of E. coli in the cecum were not identical to differences in the small intestine, the changes of E. coli in the cecurn had a similar trend.

• Journal of Microbiology and Biotechnology
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• v.1 no.2
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• pp.130-135
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• 1991

The effects of media composition on citric acid fermentation using surface immobilized Saccharomycopsis lipolytica were studied. The use of the standard medium for these organisms resulted in rapid decrease of citric acid production and a transformation of immobilized cell morphologies from a yeast-type to a mycelium-type. When the standard medium was enriched with vitamins, trace minerals, a growth factor and ammonium to form a Vigorous Stationary Phase (VSP) fermentation type medium, relatively stable citric acid production (10 mg/lㆍh) was obtained. Using the VSP type medium, the surface immobilized cells also retained their yeast-type form.

• Food Science and Biotechnology
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• v.16 no.3
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• pp.485-488
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• 2007

Plentiful amount of spent yeast has been produced as a by-product from breweries. ${\beta}-Glucan$ was prepared from the spent brewer's yeast in a crude form with hot water extraction and subsequent enzymatic treatment. The crude ${\beta}-glucan$ preparation consisted of mainly glucan (53% of total wt), containing approximately 35% ${\beta}-glucan$ content of total weight. The effects of crude ${\beta}-glucan$ substitution (1-9%) on pasting properties of wheat flour and starch were determined using a Rapid Visco-Analyzer (RVA). Incorporation of yeast ${\beta}-glucan$ into wheat flour and starch significantly decreased peak and [mal viscosities, but slightly increased setback viscosity. The setback viscosity was considerably higher in starch/${\beta}-glucan$ suspension than in flour/${\beta}-glucan$ suspension. It was suggested that preparation of yeast ${\beta}-glucan$ into aqueous dispersion might affect pasting behaviors of wheat flour and starch.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1146-1151
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• 2005

The yeast Candida albicans has a distinguishing feature, dimorphism, which is the ability to switch between two morphological forms: a budding yeast form and a multicellular invasive filamentous form. This ability has been postulated to contribute to the virulence of this organism. Previously, we reported that the yeast-to-hypha transition in this organism is suppressed by farnesoic acid, a morphogenic autoregulatory substance that accumulates in the medium as the cells proliferate. In this study, using a differential display reverse transcription polymerase chain reaction (DDRT-PCR) technique, we have identified several genes induced in C. albicans by farnesoic acid treatment. These observations indicate that farnesoic acid can alter the expressivity of multiple genes, including the DNA replication machinery and cell-cycle-control proteins.

• Journal of Microbiology and Biotechnology
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• v.20 no.5
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• pp.942-945
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• 2010

The ability of the human fungal pathogen Candida albicans to undergo the morphological transition from a single yeast form to pseudohyphal and hyphal forms in response to various conditions is known to be important for its virulence. Many studies have shown the pharmacological effects of resveratrol, a phytoalexin polyphenolic compound. In this study, we investigated the antifungal activity of resveratrol against C. albicans. Both yeast-form and mycelial growth of C. albicans were inhibited by resveratrol. In addition, normal filamentation of C. albicans was affected and yeast-to-hypha transition under serum-, pH-, and nutrient-induced hyphal growth conditions was impaired by resveratrol.

• The Microorganisms and Industry
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• v.19 no.4
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• pp.32-35
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• 1993

ras는 활성화 형태인 GTP bound form과 비활성화 형태인 GDP bound form의 두 형태로 존재하며 두 형태를 매개하는 regulatory protein들에 의해 그 activity가 조절된다. 또한 ras는 GTP와 GDP에 강한 친화성이 있으며 세포내에는 GTP보다 GDP가 더 많이 있어서 평소에는 ras가 GDP와 결합하고 있다가 활성화될때만 GTP와 결합하는 것으로 추정된다. GDP bound ras는 guanine nucloetide exchange protein(GEP)에 의해 활성화된 GTP bound form으로 전환되며 ras의 기능이 발휘된 후에는 GTPase activating protein(GAP)에 의해 비활성화된다. Yeast의 경우 IRA1과 2의 product가 GAP의 역할을 하는 것으로 알려져 있고 CDC25 gene의 product가 GEP의 기능을 담당하는 것으로 알려져 있다. NF1 gene은 Von Recklinghausen Neurofibromatosis Type I 질병을 가진 환자에게서 발견되었는데 부분적으로 sequencing한 결과에 따르면 yeast의 IRA1/2, mammalian GAP gene product와 protein homology가 높은 것으로 나타났다. Yeast의 경우 IRA1/2 gene의 손실이나 mammalian ras gene의 transformation으로 인한 heat shock sensitivity가 NF1 gene(2,3) 혹은 GAP(4)의 expression으로 suppression된 것으로 보아 NF1이 GAP protein으로서 ras를 불활성화 시킨다는 것이 판명되었다. 결론적으로 ras의 활성은 GTP bound 혹은 GDP bound의 양쪽형태를 이동하면서 조절되는데 이 기능은 GAP과 GEP 또는 그의 유사 protein들에 의해 수행되며 이러한 regulatory protein들은 growth factor, cytokine 그리고 protein kinase 같은 signal에 의해 활성화된다고 생각된다. 본 총설에서는 ras protein의 여러가지 성질보다는 ras의 modification과 관련하여 항암제로 사용할 수 있는 ras에 specific한 약품개발의 가능성과 현재 알려진 ras의 inhibitor를 중심으로 논하고자 한다.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1597-1604
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• 2006

To screen for an anti-yeast substance (AYS), many bacteria were isolated from soil and a strain AY2000 was selected. The strain AY2000 was identified as Rahnella aquatilis by morphology, biochemical properties, and 16S r-RNA nucleotide sequence analyses. The strain AY2000 showed anti-yeast activity against Candida albicans and Saccharomyces cerevisiae, whereas R. aquatilis ATCC33071 as a type strain did not show the activity against the yeasts under the same condition. The growth of yeast cell was significantly inhibited by AYS produced by the strain AY2000, as shown by optical density and MTT assay. The minimum inhibitory concentration (MIC) of the AYS against S. cerevisiae and C. albicans at $28^{\circ}C\;was\;20{\mu}g/ml\;and\;60{\mu}g/ml$, respectively. The MIC of AYS against hyphae of C. albicans at $37^{\circ}C\;was\;600{\mu}g/ml$. Scanning electron microscopic analysis revealed that yeast cells treated with AYS had an irregular form with a wrinkled and rough surface.

• The Korean Journal of Mycology
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• v.23 no.4 s.75
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• pp.310-317
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• 1995

The evolutionary relationships for 43 species in the taxa of the basidiomycetous yeast and related yeast-like fungi have been studied from the 43 18S rRNA partial sequences. Fibulobasidium inconspicuum showed a relatively close relationship to Filobasidiella neoformans. It is obvious that Tremella foliacea and Ustilogo rabenhorstiana form a independently different cluster from basidiomycetous yeast and seem to be phylogenetically distant from basidiomycetous yeast and each other. The basidiomycetous yeasts are believed more closely associated with Tremella foliacea than with Ustilago rabenhorstiana. The phenotypic criteria such as carotenoid pigments, teliospores, ballistospores seems not to be phylogenetically useful indicators.

• The Korean Journal of Mycology
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• v.44 no.2
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• pp.87-93
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• 2016

From 182 non-pathogenic wild yeast isolates from flowers, Pichia silvicola UL6-1 and Sporobolomyces carnicolor 402-JB-1 were selected for potent ${\gamma}$-aminobutyric acid production and microbiological characteristics were investigated. Pichia silvicola UL6-1 formed ascospores and pseudomycelia. The strain was also halotolerant, growing well in 5% NaCl-containing yeast extract-peptone-dextrose (YPD) medium. Sporobolomyces carnicolor 402-JB-1 did not form ascospores or pseudomycelia and grew well on 10% glucose-yeast extract-peptone medium.