• 한국균학회지
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• 제42권2호
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• pp.178-182
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• 2014

효모는 엽권의 중요한 서식자이지만, 효모의 분포와 역할을 정확하게 이해하고 있지 못한 형편이다. 2013년 봄과 가을에, 대전시 서구 만년동에 위치한 한밭 수목원에 식재되어 있는 각종 꽃과 과일로부터 효모를 분리하였다. 분리된 효모 집락을 PCR 방법에 의해 26S rDNA의 D1/D2 지역을 증폭하고 염기서열을 결정한 후, BLAST를 이용하여 데이터베이스와 비교하여 효모를 동정하였다. 그 결과 29종의 꽃과 6종의 과일로부터, 14속 31종에 속하는 효모를 57균주를 분리하였다. 그 결과 봄과 가을, 계절에 따라서 같은 수목원에서 분리되는 효모 종에 현저한 차이가 있는 것을 발견하였다.

• Molecules and Cells
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• 제39권7호
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• pp.550-556
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• 2016

During meiosis, exchange of DNA segments occurs between paired homologous chromosomes in order to produce recombinant chromosomes, helping to increase genetic diversity within a species. This genetic exchange process is tightly controlled by the eukaryotic RecA homologs Rad51 and Dmc1, which are involved in strand exchange of meiotic recombination, with Rad51 participating specifically in mitotic recombination. Meiotic recombination requires an interaction between homologous chromosomes to repair programmed double-strand breaks (DSBs). In this study, we investigated the budding yeast meiosis-specific proteins Hop2 and Sae3, which function in the Dmc1-dependent pathway. This pathway mediates the homology searching and strand invasion processes. Mek1 kinase participates in switching meiotic recombination from sister bias to homolog bias after DSB formation. In the absence of Hop2 and Sae3, DSBs were produced normally, but showed defects in the DSB-to-single-end invasion transition mediated by Dmc1 and auxiliary factors, and mutant strains failed to complete proper chromosome segregation. However, in the absence of Mek1 kinase activity, Rad51-dependent recombination progressed via sister bias in the $hop2{\Delta}$ or $sae3{\Delta}$ mutants, even in the presence of Dmc1. Thus, Hop2 and Sae3 actively modulate Dmc1-dependent recombination, effectively progressing homolog bias, a process requiring Mek1 kinase activation.

• Journal of Microbiology and Biotechnology
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• 제28권1호
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• pp.105-108
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• 2018

Beef was dry aged for 40-60 days under controlled environmental conditions in a refrigerated room with a relative humidity of 75%-80% and air-flow. To date, there is little information on the microbial diversity and characteristics of dry aged beef. In this study, we explored the effect of change in meat microorganisms on dry aged beef. Initially, the total bacteria and LAB were significantly increased for 50 days during all dry aging periods. There was an absence of representative foodborne pathogens as well as coliforms. Interestingly, fungi including yeast and mold that possess specific features were observed during the dry aging period. The 5.8S rRNA sequencing results showed that potentially harmful yeasts/molds (Candida sp., Cladosporium sp., Rhodotorula sp.) were present at the initial point of dry aging and they disappeared with increasing dry aging time. Interestingly, Penicillium camemberti and Debaryomyces hansenii used for cheese manufacturing were observed with an increase in the dry aging period. Taken together, our results showed that the change in microorganisms exerts an influence on the quality and safety of dry aged beef, and our study identified that fungi may play an important role in the palatability and flavor development of dry aged beef.

• Mycobiology
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• 제38권1호
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• pp.17-25
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• 2010

The common split-gilled mushroom, Schizophyllum commune is found throughout the world on woody plants. This study was initiated to evaluate conditions for favorable vegetative growth and to determine molecular phylogenetic relationship in twelve different strains of S. commune. A suitable temperature for mycelial growth was obtained at $30^{\circ}C$. This mushroom grew well in acidic conditions and pH 5 was the most favorable. Hamada, glucose peptone, Hennerberg, potato dextrose agar and yeast malt extract were favorable media for growing mycelia, while Lilly and glucose tryptone were unfavorable. Dextrin was the best and lactose was the less effective carbon source. The most suitable nitrogen sources were calcium nitrate, glycine, and potassium nitrate, whereas ammonium phosphate and histidine were the least effective for the mycelial growth of S. commune. The genetic diversity of each strain was investigated in order to identify them. The internal transcribed spacer (ITS) regions of rDNA were amplified using PCR. The size of the ITS1 and ITS2 regions of rDNA from the different strains varied from 129 to 143 bp and 241 to 243 bp, respectively. The sequence of ITS1 was more variable than that of ITS2, while the 5.8S sequences were identical. A phylogenetic tree of the ITS region sequences indicated that the selected strains were classified into three clusters. The reciprocal homologies of the ITS region sequences ranged from 99 to 100%. The strains were also analyzed by random amplification of polymorphic DNA (RAPD) with 20 arbitrary primers. Twelve primers efficiently amplified the genomic DNA. The number of amplified bands varied depending on the primers used or the strains tested. The average number of polymorphic bands observed per primer was 4.5. The size of polymorphic fragments was obtained in the range of 0.2 to 2.3 kb. These results indicate that the RAPD technique is well suited for detecting the genetic diversity in the S. commune strains tested.

• Journal of Microbiology and Biotechnology
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• 제21권12호
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• pp.1270-1279
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• 2011

Bealmijang is a short-term aged paste made from meju, which is a brick of fermented soybeans and other ingredients. Different types of bealmijang are available depending on the geographic region or ingredients used. However, no study has clarified the microbial diversity of these types. We identified 17 and 14 fungal species from black soybean meju (BSM) and buckwheat meju (BWM), respectively, on the basis of morphology, culture characteristics, and internal transcribed spacer and ${\beta}$-tubulin gene sequencing. In both meju, Aspergillus oryzae, Rhizopus oryzae, Penicillium polonicum, P. steckii, Cladosporium tenuissimum, C. cladosporioides, C. uredinicola, and yeast species Pichia burtonii were commonly found. Moreover, A. flavus, A. niger, P. crustosum, P. citrinum, Eurotium niveoglaucum, Absidia corymbifera, Setomelanomma holmii, Cladosporium spp. and unclassified species were identified from BSM. A. clavatus, Mucor circinelloides, M. racemosus, P. brevicompactum, Davidiella tassiana, and Cladosporium spp. were isolated from BWM. Fast growing Zygomycetous fungi is considered important for the early stage of meju fermentation, and A. oryae and A. niger might play a pivotal role in meju fermentation owing to their excellent enzyme productive activities. It is supposed that Penicillium sp. and Pichia burtonii could contribute to the flavor of the final food products. Identification of this fungal diversity will be useful for understanding the microbiota that participate in meju fermentation, and these fungal isolates can be utilized in the fermented foods and biotechnology industries.

• 한국균학회지
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• 제46권2호
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• pp.98-104
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• 2018

우리나라 3대 강의 하나인 금강의 물과 주변 토양들의 야생효모들의 분포 특성을 알아보기 위해 먼저 금강 중류지역인 공주시 청벽대교 밑을 흐르는 금강의 물과 주변 토양들을 2017년 10월에 45점을 채취하여 야생효모들을 분리, 동정하였고 이들 중 국내 미기록 효모들을 선별하여 이들의 균학적 특성을 조사하였다. 이들 금강 중류 시료들로부터 24종 51균주가 분리되었고 이들 중 가장 많이 분리된 야생효모는 Cryptococcus magnus 7주를 포함한 Cryptococcus속 균으로 11주가 분리되었고 Rhodotorula속 균과 Hanseniaspora속 균들이 우점균으로 많이 분리 되었다. Candida chauliodes WJSF 0201, Candida oleophila WJSF 0202, Candida catenulata WJSF 0203, Candida jaroonii WJSF 0204 등 4균주들이 국내 미기록 효모 균주들로 선별되었고 이들 야생효모들은 구형으로 출아법으로 영양증식하였다. 모든 미기록 효모 균주들이 비타민을 함유하지 않은 yeast extract-peptone-dextrose (YPD) 배지에서도 잘 생육하였고 5% NaCl를 함유한 YPD 배지에서 생육하는 내염성 효모들이었다. 특히, Candida oleophila WJSF 0202는 $37^{\circ}C$에서도 생육하는 고온성 효모로 내열성 효소 등 산업적으로 매우 유용할 것으로 생각된다.

• 한국균학회지
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• 제50권3호
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• pp.149-160
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• 2022

남해안과 금강상류 주변환경의 야생효모들의 효모 종 분포특성을 조사하고 국내 미보고된 효모들을 선별하여 이들의 균학적 특성들을 알아보고자 남해안의 해금강과 금강상류인 전북 무주의 남대천 및 금산의 금산천 주변의 물과 토양들로부터 야생효모들을 분리, 동정하였다. 해금강 주변 시료 35점에서 22종 52균주의 야생효모들을 분리, 동정하였고 무주의 남대천 주변 물과 토양 30점에서는 24 종 43균주의 야생효모들을, 금산의 금산천변 시료 60점에서 45종 79균주의 야생효모들을 분리, 동정하였다. 이들 지역에서 분리, 동정한 야생효모들중 Exobasidium rhododendri HHG10-5 (NNIBR2022633FG1), Udeniomyces pyricola NDC29-1 (NNIBR2022633FG2), Pichia scaptomyzae BAC2-3 (NNIBR2022633FG4), Diddensiella caesifluorescens GSC2-2 (NNIBR2022633FG5) 등 4균주들이 국내 미기록 야생효모들로 최종 선별되었다. 이들의 균학적 특성을 조사한 결과Udeniomyces pyricola NDC29-1 과Diddensiella caesifluorescens GSC2-2 균은 구형이었고 Exobasidium rhododendri HGG10-5 와 Pichia scaptomyzae BAC2-2 균들은 난형이었으며 Pichia scaptomyzae BAC2-3 균주만이 포자를 생성하였다. Udeniomyces pyricola NDC29-1 균주 외에는모두 vitamin-free배지에서도생육이아주양호하였고Pichia scaptomyzae BAC2-3, Diddensiella caesifluorescens GSC2-2 균주는 40% glucose 를함유한 YPD배지에서도생육하는내당성균이었다. Udeniomyces pyricola NDC29-1 균주를 제외한 나머지 균들은 Ca 등의 중금속등에 대하여 강한 내성을보였다.

• BMB Reports
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• 제52권10호
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• pp.607-612
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• 2019

During meiosis, programmed double-strand breaks (DSBs) are repaired via recombination pathways that are required for faithful chromosomal segregation and genetic diversity. In meiotic progression, the non-homologous end joining (NHEJ) pathway is suppressed and instead meiotic recombination initiated by nucleolytic resection of DSB ends is the major pathway employed. This requires diverse recombinase proteins and regulatory factors involved in the formation of crossovers (COs) and non-crossovers (NCOs). In mitosis, spontaneous DSBs occurring at the G1 phase are predominantly repaired via NHEJ, mediating the joining of DNA ends. The Ku complex binds to these DSB ends, inhibiting additional DSB resection and mediating end joining with Dnl4, Lif1, and Nej1, which join the Ku complex and DSB ends. Here, we report the role of the Ku complex in DSB repair using a physical analysis of recombination in Saccharomyces cerevisiae during meiosis. We found that the Ku complex is not essential for meiotic progression, DSB formation, joint molecule formation, or CO/NCO formation during normal meiosis. Surprisingly, in the absence of the Ku complex and functional Mre11-Rad50-Xrs2 (MRX) complex, a large portion of meiotic DSBs was repaired via the recombination pathway to form COs and NCOs. Our data suggested that Ku complex prevents meiotic recombination in the elimination of MRX activity.

• 한국균학회지
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• 제51권4호
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• pp.491-504
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• 2023

To explore fungal diversity in orchard soil where fire-blighted apple trees are buried, we collected soil samples from apple orchards in Chungju, Korea. Fungal isolates were obtained from DG18 agar and identified at the species level based on morphological features and phylogenetic analyses. The colony characteristics and microstructures were examined using a light microscope and a scanning electron microscope after culturing on potato dextrose agar (PDA), malt extract agar (MEA), Czapek yeast agar (CYA), and oatmeal agar (OA) The PCR-amplified products of the ITS1-5.8S-ITS2 region and 28S large subunit of the nuclear ribosomal RNA gene, as well as partial sequences of the β-tubulin, calmodulin, and translation elongation factor 1-α genes were sequenced and analyzed phylogenetically. Seven previously unknown fungal species were explored in Korea. All samples, including Aspergillus aureolatus, Botryotrichum atrogriseum, Dactylonectria novozelandica, Fusarium denticulatum, Paecilomyces tabacinus, Sarcopodium tibetense and Talaromyces stollii, had ascomycetes. Herein, we report their descriptions and features.

• Asian-Australasian Journal of Animal Sciences
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• 제33권6호
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• pp.1002-1011
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• 2020

Objective: This study was conducted to determine the composition and diversity of the fungal flora at various control points in cheese ripening rooms of 10 dairy farms from six different provinces in the Republic of Korea. Methods: Floor, wall, cheese board, room air, cheese rind and core were sampled from cheese ripening rooms of ten different dairy farms. The molds were enumerated using YM petrifilm, while isolation was done on yeast extract glucose chloramphenicol agar plates. Morphologically distinct isolates were identified using sequencing of internal transcribed spacer region. Results: The fungal counts in 8 out of 10 dairy farms were out of acceptable range, as per hazard analysis critical control point regulation. A total of 986 fungal isolates identified and assigned to the phyla Ascomycota (14 genera) and Basidiomycota (3 genera). Of these Penicillium, Aspergillus, and Cladosporium were the most diverse and predominant. The cheese ripening rooms was overrepresented in 9 farms by Penicillium (76%), while Aspergillus in a single farm. Among 39 species, the prominent members were Penicillium commune, P. oxalicum, P. echinulatum, and Aspergillus versicolor. Most of the mold species detected on surfaces were the same found in the indoor air of cheese ripening rooms. Conclusion: The environment of cheese ripening rooms persuades a favourable niche for mold growth. The fungal diversity in the dairy farms were greatly influenced by several factors (exterior atmosphere, working personnel etc.,) and their proportion varied from one to another. Proper management of hygienic and production practices and air filtration system would be effective to eradicate contamination in cheese processing industries.