• Journal of Microbiology and Biotechnology
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• 제26권11호
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• pp.1891-1907
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• 2016

Yeasts that are present in marine environments have evolved to survive hostile environments that are characterized by high exogenous salt content, high concentrations of inhibitory compounds, and low soluble carbon and nitrogen levels. Therefore, yeasts isolated from marine environments could have interesting characteristics for industrial applications. However, the application of marine yeast in research or industry is currently very limited owing to the lack of a suitable isolation method. Current methods for isolation suffer from fungal interference and/or low number of yeast isolates. In this paper, an efficient and non-laborious isolation method has been developed and successfully isolated large numbers of yeasts without bacterial or fungal growth. The new method includes a three-cycle enrichment step followed by an isolation step and a confirmation step. Using this method, 116 marine yeast strains were isolated from 14 marine samples collected in the UK, Egypt, and the USA. These strains were further evaluated for the utilization of fermentable sugars (glucose, xylose, mannitol, and galactose) using a phenotypic microarray assay. Seventeen strains with higher sugar utilization capacity than the reference terrestrial yeast Saccharomyces cerevisiae NCYC 2592 were selected for identification by sequencing of the ITS and D1/D2 domains. These strains belonged to six species: S. cerevisiae, Candida tropicalis, Candida viswanathii, Wickerhamomyces anomalus, Candida glabrata, and Pichia kudriavzevii. The ability of these strains for improved sugar utilization using seawater-based media was confirmed and, therefore, they could potentially be utilized in fermentations using marine biomass in seawater media, particularly for the production of bioethanol and other biochemical products.

• Mycobiology
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• 제38권3호
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• pp.171-175
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• 2010

Metacordyceps yongmunensis is a newly reported species from Korea, which is very similar to Cordyceps species in morphological characters. It grows on large lepidopteran pupa, and numerous white stromata grow on a single host. Mycelial growth characteristics of M. yongmunensis isolates were studied in different media and at different temperatures. Also, different carbon sources, nitrogen sources, and mineral salts were tested for mycelial growth of M. yongmunensis. Schizophyllum (mushroom) genetics complete medium plus yeast extract, Schizophyllum (mushroom) genetics minimal medium, and Martin's peptone dextrose agar produced longer colony diameters and more compact mycelial density than other media. The optimum temperature for mycelial growth was $25^{\circ}C$. Carbon sources such as sucrose, soluble starch, dextrose, glucose, dextrin, maltose, and fructose showed better mycelial growth, whereas peptone, yeast extract and tryptone resulted in the best mycelial growth of all of the nitrogen sources tested. All of the mineral salts tested showed similar growth as the control, except $K_2HPO_4$ which showed longer colony diameter and more compact mycelial density. The compact colonies were white and cottony with a greenish margin. The results showed that M. yongmunensis is an easy fungus to growas it grew from 30 to more than 50 mm in 2 wk.

• 한국가시화정보학회지
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• 제21권3호
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• pp.93-100
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• 2023

The yeast Saccharomyces cerevisiae (S. cerevisiae) is considered an ideal eukaryotic model and has long been recognized for its pivotal role in numerous industrial production processes. Depending on the cell cycle phases, microenvironment, and species, S. cerevisiae varies in shape and has different sizes of each shape such as singlets, doublets, and clusters. Obtaining high-purity populations of uniformly shaped S. cerevisiae cells is crucial in fundamental biological research and industrial operations. In this study, we propose an acoustofluidic method for separating S. cerevisiae cells based on their size using surface acoustic wave (SAW)-induced acoustic radiation force (ARF). The SAW-induced ARF increased with cell diameter, which enabled a successful size-based separation of S. cerevisiae cells using an acoustofluidics device. We anticipate that the proposed acoustofluidics approach for yeast cell separation will provide new opportunities in industrial applications.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2002년도 추계학술대회
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• pp.90-93
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• 2002

The revolution in molecular biology has given us greatly increased ability to obtain and to modify biological resources and to use them for the benefit of all humankind. The sequencing and the associated analysis of gene functions for a growing number of genomes will have an unprecedented effect on the uses of biological resources and the need for access to them. To investigate the diversity of microbial community in swamp, molecular systematic methods were applied. By amplified rDNA restriction analysis (ARDRA) and rDNA partial sequence analysis, $75\%$ of the isolates were known species. In case of uncultured analysis, almost all the selected clones were new species candidate. Especially archea and uncultured bacterial analyses, all clones were new taxon candidates. As for the eukaryotic diversity, several yeast form cultures were isolated from various samples of swamp. Among them, about $60\%$ of the isolates were easily identified. In case of a new species candidate, most strain were included in hymenomycetal yeasts.

• 한국균학회지
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• 제46권4호
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• pp.383-392
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• 2018

During the study of indigenous fungal communities in soil samples collected from various field soils in Sancheong, Gyeongsangnam-do, Korea in 2017, several species of Aspergillus were discovered. Aspergillus caninus (KNU17-7) was isolated, identified, and described based on the results from macro and micro morphological characteristics and molecular characterization. Morphologically, it was identified using five different growth media: potato dextrose agar, oatmeal agar, yeast extract sucrose agar, czapek yeast extract agar, and malt extract agar. For the molecular identification, sequencing of internal transcribed spacer, ${\beta}-tubulin$, and calmodulin genes was performed. Based on this characterization, our study isolate was identified as Aspergillus caninus. This fungal species has not been officially reported in Korea before, and we report here with its morphological and molecular phylogenetic characterization.

• 한국수산과학회지
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• 제35권4호
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• pp.342-347
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• 2002

섬모충은 윤충류보다 다양한 크기를 가지고 있으며, 얇은 세포벽, 느린 운동성, 빠른 번식률로 새로운 동물성 먹이생물로써 개발가능성을 가지고 있다. 한국 연안 수역인 수영만, 광양만 및 경기만 소래 염전지역에서 식물성 플랑크톤 네트를 이용하여 6종의 섬모충을 채집하였으며, capillary pipette로 분리 $\cdot$배양하였다. 먹이생물로써의 개발가능성을 파악하기 위하여 크기, 운동성, 배양밀도 및 부유능력을 평가하였으며, 채집된 섬모충류 가운데 광양만에서 채집된 Euplotes sp. (K-1)가 가장 적합한 것으로 평가되었다. MErds 기본배지에 glycine, glucose, yeast extract을 각 0.1 g씩 첨가하여 변형한 MErds-2 배지는 기본배지보다도 약 6배의 번식률을 보여, Euplotes sp.를 비롯한 기타 섬모충 배양배지로도 유용하였다. Euplotes sp. (K-1)은 수온 $22.5^{\circ}C$, pH 8,조도 2,000 lux에서 각각 최고의 번식률을 보였으며, 이들 환경조건에 대해 비교적 폭넓은 환경적응력을 나타내었다. 한편, 빵효모 1.0 g/L의 첨가에 의해서도 대량배양이 가능하였다. 본 연구에서의 섬모충은 종보관이 용이하며 폭넓은 환경 적응력과 간단한 방법의 대량배양이 가능하여 초기 동물성 먹이생물로써의 높은 잠재력을 가지고 있는 것으로 평가되었다.

• Mycobiology
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• 제40권4호
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• pp.255-257
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• 2012

Among 80 types of yeast isolated from wild flowers in Daejeon, Korea, two species that have not yet been identified by phylogenetic analysis of the internal transcribed spacer-2 (ITS2) genes and 26S rDNA sequences were identified as Candida sp. 44-C-1 and Cryptococcus sp. 9-D-1. Neither of the newly identified species formed ascospores, while Candida sp. 44-C-1 formed pseudomycelium and Cryptococcus sp. 9-D-1 did not.

• 한국환경성돌연변이발암원학회지
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• 제19권1호
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• pp.28-33
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• 1999

The SNF2 family includes proteins from a variety of species with roles I cellular processes such as transcriptional regulation, recombination and various types of DNA repair. Several proteins with unknown function are also included in this family. Here, we report the cloning and characterization of hrp 2+ gene (helicase related gene from S. pombe) which was isolated by PCR amplication using the conserved domain of SNF2 motifs within the ERCC6 gene which encodes a protein involved in DNA excision repair. The hrp2+ gene was isolated by screening with yeast S. pombe genomic library. The isolated cloned contained 6.5 kb insert DNA. Southern blot analysis confirmed that S. pombe chromosome contains the same DNA as hrp2+ gene and this gene exists as a single copy in S. pombe genome. The 4.7 kb transcript of mRNA was identified by Northern blot. To examined the transcriptional regulation of hrp2+ gene, DNA damaging agents were treated. These results indicated that the hrp2+ gene may not be directly involved in DNA replication, but may be involved in damage response pathway.

• Journal of Applied Biological Chemistry
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• 제43권4호
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• pp.211-217
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• 2000

Oxidative stress is implicated in a number of diseases, in ageing of organisms, and in damage to plants that have been exposed to freezing and thawing or water stress. From the perspective of yeast as a model eukaryotic system, this article reviews the systems that are involved in the cellular responses to exposure to reactive oxygen species (ROS) generated during aerobic growth of the organism. The discussion includes the defense systems involved, the ability of cells to adapt to ROS treatment, cell-division cycle delay and the systems regulating gene expression that are activated by oxidative stress.

• BMB Reports
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• 제40권1호
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• pp.82-87
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• 2007

Our heterologous expression system of the human ferritin H-chain gene (hfH) allowed us to characterize the cellular effects of ferritin in yeasts. The recombinant Saccharomyces cerevisiae (YGH2) evidenced impaired growth as compared to the control, which was correlated with ferritin expression and with the formation of core minerals. Growth was recovered via the administration of iron supplements. The modification of cellular iron metabolism, which involved the increased expression of high-affinity iron transport genes (FET3 and FTR1), was detected via Northern blot analysis. The findings may provide some evidence of cytosolic iron deficiency, as the genes were expressed transcriptionally under iron-deficient conditions. According to our results examining reactive oxygen species (ROS) generation via the fluorescence method, the ROS levels in YGH2 were decreased compared to the control. It suggests that the expression of active H-ferritins reduced the content of free iron in yeast. Therefore, present results may provide new insights into the regulatory network and pathways inherent to iron depletion conditions.