• Journal of Microbiology and Biotechnology
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• 제32권7호
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• pp.877-884
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• 2022

Probiotics are microorganisms that can benefit host health when ingested in a live state, and lactic acid bacteria are the most common type. Among fungi, Saccharomyces boulardii (SB) is the only strain known to have a probiotic function with beneficial effects on colitis; however, information on other probiotic yeast strains is limited. Therefore, this study aimed to discover yeast strains expressing intestinal anti-inflammatory activities by exhibiting probiotic properties in dextran sodium sulfate (DSS)-induced colitis mice model. Nuruk (Korean traditional fermentation starter) containing various microbial strains was used as a source for yeast strains, and S. cerevisiae 28-7 (SC28-7) strain was selected with in vitro and in vivo characteristics to enable survival in the intestines. After 14 days of pretreatment with the yeast strains, DSS was co-administered for six days to induce colitis in mice. The results revealed that the disease activity index score was lowered by SC28-7 treatment compared to the DSS group, and the colon length and weight/length ratio were recovered in a pattern similar to that of the normal group. SC28-7 administration significantly reduced the secretion of pro-inflammatory cytokines in the serum and modified the mRNA expression of inflammatory cytokines (interleukin-1β, transforming growth factor-β, and interferon-γ) and proteins involved in gut barrier functions (mucin 2, mucin 3, zonula occludens-1, and occludin) in colon tissues. These results indicate that SC28-7 attenuates DSS-induced colon damage and inflammation, supporting its future use as a probiotic yeast for treating and preventing intestinal inflammatory diseases such as inflammatory bowel disease.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 춘계학술대회 및 임시총회
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• pp.30-30
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• 2014

We isolated various yeasts from wild flowers in main islands, Jejudo, Ulleungdo and Yokjido of Korea and their yeasts were identified by comparison of their PCR-amplified D1/D2 regions of 26S rDNA using the BLAST database. Thirty two yeast strains of fourteen species were isolated from wild flowers of Jejudo. Forty eight yeast strains of twenty two species were isolated and identified from wild flowers of Ulleungdo, Korea. Sixty yeast strains belonged to twenty five species were isolated identified from wild flowers of Yokjido in Tongyeong, Korea. Only Metschnikowia reukaufii was overlapped from the three different islands areas. Two species overlapped from Jejudo and Ulleungdo: Pichia guilliermondii, Metschnikowia reukaufii. Seven species were overlapped from Ulleungdo and Yokjido: Cryptococcus albidus, Cryptococcus laurentii, Metschnikowia reukafii, Pichia scolyti, Rhodotorula glutinis, Rhodotorula graminis and Rhodotorula mucilaginosa. Four species were overlapped from Jejudo and Yokjido: Candida sp. Cryptococcus aureus, Metschnikowia reukafii and Pseudozyma sp.

• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1702-1710
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• 2010

Korean traditional rice wines yakju and takju are generally brewed with nuruk as the source of the saccharogenic enzymes by natural fermentation. To improve the quality of Korean rice wine, the microorganisms in the nuruk need to be studied. The objective of this research was to improve the quality of Korean wine with the wild-type yeast strains isolated from the fermentation starter, nuruk. Only strain YA-6 showed high activity in 20% ethanol. Precipitation of Y89-5-3 was similar to that of very flocculent yeast (>80%) at 75.95%. Using 18S rRNA sequencing, all 10 strains were identified as Saccharomyces cerevisiae. Volatile compounds present in yakju were analyzed by gas chromatography-mass selective detector. The principal component analysis (PCA) of the volatile compounds grouped long-chain esters on the right side of the first principal component, PC1; these compounds were found in yakju that was made with strains YA-6, Y89-5-3, Y89-5-2, Y90-9, and Y89-1-1. On the other side of PC1 were short-chain esters; these compounds were found in wines that were brewed with strains Y183-2, Y268-3, Y54-3, Y98-4, and Y88-4. Overall, the results indicated that using different wild-type yeast strains in the fermentation process significantly affects the chemical characteristics of the glutinous rice wine.

• Journal of Microbiology
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• 제34권4호
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• pp.327-333
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• 1996

Yeast, like many other microbes, encounters large variations in ambient pH in their natural environments. Microorganisms capable of growing over a wide pH range require a versatile, efficient pH homeostatic mechanism protecting intracellular processes against extremes of pH. In several organisms, fusions to the bacterial lacZ gene have been extremely useful for the identification of genes expressed at different time during the life cycle or under different growth conditions. In this study, using the lacZ gene screening system, we surveyed a large number of yeast strains with lacZ insertion to identify genes regulated by pH. A yeast genomic library was constructed and inserted with lacZ by a shuttle mutagenesis procedure. The yeast transformants were individually picked up with a toothpick, replica-plated, and grown in alkaline pH medium. Among the 35,000 colonies screened, 10 candidate strains were identified initially by the $\beta$-gal assay. We finally confirmed two yeast strains carrying the genes whose expression are strictly dependent on pH of growth medium. One of the fusions showing a 10-fold induction in expression level in response to alkali pH was selected and further characterized. The pH-regulated gene was cloned by inverse PCR and a partial sequence of the gene was determined. Identification and characterization of the gene is currently under investigation.

• Mycobiology
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• 제48권4호
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• pp.296-303
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• 2020

Three yeast strains (Hue-1, Hue-8, and Hue-19) with strong heavy metal tolerance were isolated from mangosteen from Hue city, Vietnam. They exhibited identical phenotype and phylogeny. Sequence analysis of the D1/D2 region of the LSU rRNA gene and the internal transcribed spacer (ITS) region demonstrated that the closest relative of these strains is Papiliotrema sp. with 2.12% and 3.55-3.7% divergence in the D1/D2 domain, and ITS domain, respectively. Based on the physiological, biochemical, and molecular data, the three strains belong to a novel species of Papiliotrema genus, for which the name Papiliotrema huenov sp. nov. is proposed. These strains are highly tolerant of heavy metals compared to other yeasts, being able to grow in the presence of 2 mM Pb (II), 2 mM Cd (II), and up to 5 mM Ni (II), but no growth was observed in the presence of 1 mM As (III).

• 한국균학회지
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• 제51권4호
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• pp.361-371
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• 2023

The study was undertaken to isolate and characterize wild yeast strains from soil samples collected in Seoul, Korea. Among the 19 yeast strains obtained, 17 were previously recorded species. The remaining two strains, Wickerhamomyces sp. GW1-4 and Archaeorhizomyces sp. YB4-103 were new species candidates. The genomic and microbiological characteristics of GW1-4 and YB4-103 were investigated. Phylogenetic analyses based on the 26S rRNA gene sequences and internal transcribed sequences, GW1-4 and YB4-103, represent a distinct lineage within the family Phaffomycetaceae and Archaeorhizomycetaceae, respectively. The GW1-4 and YB4-103 strains had the highest sequence homology with Wickerhamomyces xylosivorus NBRC 111553^T (88.97%) and Archaeorhizomyces finlayi CBS 128710^T (87.55%), respectively.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권4호
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• pp.288-305
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• 2000

A review on the main aspects associated with yeast flocculation and its application in biotechnological processes is presented. This subject is addressed following three main aspects-the basics of yeast flocculation, the development of "new" flocculating yeast strains and bioreactor development. In what concerns the basics of yeast flocculation, the state of the art on the most relevant aspects of mechanism, physiology and genetics of yeast flocculation is reported. The construction of flocculating yeast strains includes not only the recombinant constitutive flocculent brewer's yeast, but also recombinant flocculent yeast for lactose metabolisation and ethanol production. Furthermore, recent work on the heterologous $\beta$-galactosidase production using a recombinant flocculent Saccharomyces cerevisiae is considered. As bioreactors using flocculating yeast cells have particular properties, mainly associated with a high solid phase hold-up, a section dedicated to its operation is presented. Aspects such as bioreactor productivity and culture stability as well as bioreactor hydrodynamics and mass transfer properties of flocculating cell cultures are considered. Finally, the paper concludes describing some of the applications of high cell density flocculating bioreactors and discussing potential new uses of these systems.e systems.

• 한국미생물·생명공학회지
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• 제24권2호
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• pp.143-148
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• 1996

Thousand actinomycetes and 50 soil samples were used for the isolation of microorganisms producing yeast cell wall lytic enzymes. Among 493 strains producing large clear zones on autolysed washed yeast (AWY), 117 strains were selected on living yeast cell agar plates. With the method of lytic activity, one strain (St-1702) was selected, which was temporarily identified as Streptomyces eurythermus. The optimal condition for enzyme production of this strain was partially determined as follows: incubation of the strain for 3 days at 30$\circ$C in the medium containing 2% freeze dried yeast cell, 1% glucose, 1% K$_{2}$HPO$_{4}$, 0.01% MgSO$_{4}$'7H$_{2}$O, 0.5% peptone, and 0.2% (NH$_{4}$)$_{2}$CO$_{3}$ with pH 7.0. The protoplast formation of yeast by using the enzyme produced by this strain was compared with commercial enzymes.

• 한국식품조리과학회지
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• 제11권1호
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• pp.9-12
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• 1995

냉동내성빵효모의 냉동내성기구를 규명하기위한 일환으로 세포의 막 유동성에 관계되는 지질분석을 행하였다. 그 결과, 냉동내성효모 $D_{2-4}$나 CFY보다 비냉동내성 효모 Saccharomyces cerevisiae 2001이 스테롤 : 인지질의 비율이 비교적 높았다. 또 인지질조성이 조사되었는 데, 세효모 모두에 있어 phosphatidylcholine 함량이 가장 높았다. Phosphatidylcholine : phosphatidylethanolamine의 비율은 냉동내성효모가 비내성효모 보다 높게 나타났다. 인지질에 연결된 지방산 함량을 보면, linoleic acid 함량은 $D_{2-4}$에서 높게 나타났으며 지방산의 불포화도는 $D_{2-4}$가 CFY나 S. cerevisiae보다 높았다. 이 결과에서 yeast 세포막의 유동성은 각 효모마다 다르며, 이것들이 저온에서의 효모의 동결장해에 영향을 주는 것으로 생각된다. 생각된다.

• Journal of Life Science
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• 제9권1호
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• pp.22-25
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• 1999

In order to study the mechanism for the adaptation to salt stress, we mutagenized budding yeast Saccharomyces cerevisiae with Ethylmethane sulfonate, and isolated salt-tolerant mutants. Among the salt-tolerant mutants, two strains exhibit additional temperature sensitive phenotype. Here, we report that these two salt-tolerant mutants are specific to {TEX}$Na^{+}${/TEX} rather than general osmotic stress. These mutant strains may contain mutations in the genes involved in {TEX}$Na^{+}${/TEX} home-ostasis.