• Journal of Microbiology and Biotechnology
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• 제20권9호
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• pp.1314-1321
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• 2010

Sulfur metabolism in S. cerevisiae is well established, but the mechanisms underlying the formation of sulfide remain obscure. Here, we investigated by real-time RT-PCR the dependence of expression levels of MET3, MET5/ECM17, MET10, MET16, and MET17 along with SSU1 on nitrogen availability in two wine yeast strains that produce divergent sulfide profiles. MET3 was the most highly expressed of the genes studied in strain PYCC4072, and SSU1 in strain UCD522. The strains behaved differently according to the sampling times, with UCD522 and PYCC4072 showing the highest expression levels at 120 h and 72 h, respectively. In the presence of 267 mg assimilable N/l, the genes were more highly expressed in strain UCD522 than in PYCC4072. MET5/ECM17 and MET17 were only weakly expressed in both strains under any condition tested. MET10 and SSU1 in both strains, but MET16 only in PYCC4072, were consistently upregulated when sulfide production was inhibited. This study illustrates that strain genotype could be important in determining enzyme activities and therefore the rate of sulfide liberation. This linkage, for some yeast strains, of sulfide production to expression levels of genes associated with sulfate assimilation and sulfur amino acid biosynthesis could be relevant for defining new strategies for the genetic improvement of wine yeasts.

• Journal of Microbiology and Biotechnology
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• 제20권11호
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• pp.1539-1545
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• 2010

In beer, glutathione works as the main antioxidant compound, which also correlates with the stability of the beer flavor. In addition, high residual sugars in beer contribute to major nonvolatile components, which are reflected in a high caloric content. Therefore, in this study, the Saccharomyces cerevisiae GSH1 gene encoding glutamylcysteine synthetase and the Saccharomycopsis fibuligera ALP1 gene encoding ${\alpha}$-amylase were coexpressed in industrial brewing yeast strain Y31 targeting the ${\alpha}$-acetolactate synthase (AHAS) gene (ILV2) and alcohol dehydrogenase gene (ADH2), resulting in the new recombinant strain TY3. The glutathione content in the fermentation broth of TY3 increased to 43.83 mg/l as compared with 33.34 mg/l in the fermentation broth of Y31. The recombinant strain showed a high ${\alpha}$-amylase activity and utilized more than 46% of the starch as the sole carbon source after 5 days. European Brewery Convention tube fermentation tests comparing the fermentation broths of TY3 and Y31 showed that the flavor stability index for TY3 was 1.3-fold higher, whereas its residual sugar concentration was 76.8% lower. Owing to the interruption of the ILV2 gene and ADH2 gene, the contents of diacetyl and acetaldehyde as off-flavor compounds were reduced by 56.93% and 31.25%, respectively, when compared with the contents in the Y31 fermentation broth. In addition, since no drug-resistant genes were introduced to the new recombinant strain, it should be more suitable for use in the beer industry, owing to its better flavor stability and other beneficial characteristics.

• Journal of Microbiology and Biotechnology
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• 제22권2호
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• pp.184-189
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• 2012

We sought to breed an industrially useful yeast strain, specifically an ethanol-tolerant yeast strain that would be optimal for ethanol production, using a novel breeding method, called genome reconstruction, based on chromosome splitting technology. To induce genome reconstruction, Saccharomyces cerevisiae strain SH6310, which contains 31 chromosomes including 12 artificial mini-chromosomes, was continuously cultivated in YPD medium containing 6% to 10% ethanol for 33 days. The 12 mini-chromosomes can be randomly or specifically lost because they do not contain any genes that are essential under high-level ethanol conditions. The strains selected by inducing genome reconstruction grew about ten times more than SH6310 in 8% ethanol. To determine the effect of mini-chromosome loss on the ethanol tolerance phenotype, PCR and Southern hybridization were performed to detect the remaining mini-chromosomes. These analyses revealed the loss of mini-chromosomes no. 11 and no. 12. Mini-chromosome no. 11 contains ten genes (YKL225W, PAU16, YKL223W, YKL222C, MCH2, FRE2, COS9, SRY1, JEN1, URA1) and no. 12 contains fifteen genes (YHL050C, YKL050W-A, YHL049C, YHL048C-A, COS8, YHLComega1, ARN2, YHL046W-A, PAU13, YHL045W, YHL044W, ECM34, YHL042W, YHL041W, ARN1). We assumed that the loss of these genes resulted in the ethanol-tolerant phenotype and expect that this genome reconstruction method will be a feasible new alternative for strain improvement.

• 생명과학회지
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• 제15권6호
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• pp.923-927
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• 2005

박테리오신의 일종인 Leucocin A를 생산하는 효모의 제작을 위하여 114 bp 길이의 종지코돈을 포함하는 Leucocin A 유전자를 합성하여 효모운반체인 pYDl에 클로닝하였다. 이렇게 제작된 재조합 DNA를 효모세포에 형질전환시켜 Leucocin A를 생산하는 형질전환 효모세포를 제작하였다. 형질전환 효모는 고초균(Bacillus subtilis)에 대해 항균활성을 나타냈다. 형질전환 효모로부터 분리한 플라스미드를 주형(template)으로 하고 Leucocin A에 특이적인 primer들을 이용하여 PCR 반응을 행한 결과, 효모에 도입된 Leucocin A 유전자를 확인할 수 있었다. 이 연구의 결과로 부패하기 쉬운 식품들의 보존성을 향상시키거나, 내성이 생긴 병원균의 생육을 저해하기 위한 항생제로 사용할 수 있는 박테리오신을 산업적으로 대량생산할 수 있는 효모세포를 제작하였다.

• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.633-643
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• 2017

To examine the pro-apoptotic role of the human ortholog (YPEL5) of the Drosophila Yippee protein, the cell viability of Saccharomyces cerevisiae mutant strain with deleted MOH1, the yeast ortholog, was compared with that of the wild-type (WT)-MOH1 strain after exposure to different apoptogenic stimulants, including UV irradiation, methyl methanesulfonate (MMS), camptothecin (CPT), heat shock, and hyperosmotic shock. The $moh1{\Delta}$ mutant exhibited enhanced cell viability compared with the WT-MOH1 strain when treated with lethal UV irradiation, 1.8 mM MMS, $100{\mu}M$ CPT, heat shock at $50^{\circ}C$, or 1.2 M KCl. At the same time, the level of Moh1 protein was commonly up-regulated in the WT-MOH1 strain as was that of Ynk1 protein, which is known as a marker for DNA damage. Although the enhanced UV resistance of the $moh1{\Delta}$ mutant largely disappeared following transformation with the yeast MOH1 gene or one of the human YPEL1-YPEL5 genes, the transformant bearing pYES2-YPEL5 was more sensitive to lethal UV irradiation and its UV sensitivity was similar to that of the WT-MOH1 strain. Under these conditions, the UV irradiation-induced apoptotic events, such as FITC-Annexin V stainability, mitochondrial membrane potential (${\Delta}{\psi}m$) loss, and metacaspase activation, occurred to a much lesser extent in the $moh1{\Delta}$ mutant compared with the WT-MOH1 strain and the mutant strain bearing pYES2-MOH1 or pYES2-YPEL5. These results demonstrate the functional conservation between yeast Moh1 and human YPEL5, and their involvement in mitochondria-dependent apoptosis induced by DNA damage.

• 한국식품과학회지
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• 제9권2호
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• pp.97-105
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• 1977

1) 효모세포벽(酵母細胞壁) 용해활성(溶解活性)이 큰 미생물을 얻기 위하여 baker's yeast-peptone-bouillon agar 평판(平板)배지에서 투명하게 용해된 부위를 형성하는 균주(菌株)를 서울 및 경기지방의 토양 및 하수(下水)시료에서 156개 분리하였고 이들중 활성(活性)이 가장 큰 균주(菌株)로 K-42를 선발하여 Bacillus circulans로 동정(同定)하였다. 2) 균주(菌株) K-42에 의한 효모세포벽 용해효소의 생산을 보면 당류 첨가의 경우 배양 2일째에는 maltose>glucan>xylose>control의 순으로, 3일째에는 lactose>galactose>glucan>control의 순으로 나타났다. 무기 질소원의 경우는 배양2일째 ammonium acetat>sodium nitrate>control의 순으로, 3일째는 ammonium chloride>ammonium oxalate>control의 순으로 나타났으며 milk casein을 제외한 거의 모든 유기질소원은 배양 2일째 활성(活性)의 증가를 보였으나 3일째는 모두 감소하였다. 당류와 질소원의 배합첨가는 상승효과가 없었다. 3) 효소생산에 미치는 당류와 질소원의 첨가 효과는 배양기간 중 pH의 변화와 깊은 관계가 있었는 바 배양중 $pH\;7{\sim}8$을 계속 유지시켜 주면서 당류 또는 질소원을 첨가하면 높은 활성(活性)을 상당기간 계속 유지할 수 있었다. 4) K-42균주(菌株)가 분비(分泌)하는 세포벽(細胞壁) 용해효소의 작용최적(作用最適) 조건은 $pH\;7{\sim}8$, $60^{\circ}C$이었고 열처리(熱處理) 효모세포벽의 용해율은 65%이었다.

• 한국균학회지
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• 제50권4호
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• pp.373-381
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• 2022

Strain E4, an unrecorded species of dimorphic fungi, was isolated from the gut of earthworms collected in Gyeonggi Province, South Korea. Nucleotide sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region revealed that this species is a member of the genus Blastobotrys, Blastobotrys illinoisensis. Strain E4 differed from its closest known species, B. mokoenaii and B. malaysiensis, by harboring 3-5 and 12-14 nucleotide substitutions in the D1/D2 and ITS regions, respectively. Phylogenetic analysis based on concatenated sequences of the D1/D2 region of the LSU rRNA gene and the ITS region also indicated that strain E4 belongs to the Blastobotrys clade and is distinct from other related species in the clade. The previously unreported isolate could be distinguished from closely related species by its inability to ferment carbon sources. To our knowledge, this is the first report on the isolation of Blastobotrys species from the gut of earthworms in Korea. The strain used was E4 (=KCTC 27831=JCM 33428).

• 한국균학회지
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• 제46권3호
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• pp.307-314
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• 2018

본 연구는 알코올 발효능이 우수한 야생 효모를 막걸리 발효에 응용할 목적으로 충남 예산군 예당저수지 야생화에서 분리한 비병원성 야생 효모들 중 에탄올 생산 우수 효모로 선발한 Aureobasidium pullulans P-1의 균학적 특성과 막걸리 발효 조건을 조사하였다. A. pullulans P-1는 출아에 의해 영양증식을 하였고 자낭포자를 생성하는 유포자 효모로서 내당성과 에탄올 내성이 강한 호염성 야생 효모이었다. A. pullulans P-1의 yeast extract-peptone-dextrose 배양액을 주모로 증자미와 입국과 물이 혼합된 술밑에 5% 첨가한 후 $25^{\circ}C$에서 1~10일간 발효시키면서 발효 중의 이화학적 성질의 변화를 조사한 결과, 에탄올 함량은 $25^{\circ}C$로 10일간 발효시켰을 때 가장 많은 8.45%를 생성하였고 관능 특성이 우수하였으며 항고혈압 활성 안지오텐신 전환효소 저해활성이 71.1%로 높았다.

• 한국균학회지
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• 제48권3호
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• pp.229-235
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• 2020

곤충 장으로부터 분리되는 야생 효모들의 종 분포특성을 알아보고자 충북대학교 주변 토양에 서서식하는 반날개과 곤충장 5점의 시료들로부터 16균주의 야생 효모들을 분리, 동정하였다. 야생 효모 16균주는Aureobasidium 속 3균주, Cystofilobasidium 속 4균주, Mrakia 속 1균주, Naganishia 속 3균주, Saitozyma 속 2균주, Sampaiozyma 속 2균주와 Scheffersomyces 속 1균주를 포함한다. 이들 중 Cystofilobasidium capitatum YP53, C. capitatum YP71, C. macerans YS620, C. macerans YS622, Mrakia aquatica YP158 및 Scheffersomyces stipitis YI56균주들을 국내 미기록 효모들로 최종 선별하였다. 선별한 국내 미기록 효모들의 균학적 특성과 탄소원의 자화성 등을 조사하였다. 이들은 모두 타원형의 세포 형태를 가지고 있으며, glycerol, L-arabinose, xylitol, inositol을 탄소원으로 이용할 수없었다.

• Applied Biological Chemistry
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• 제43권3호
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• pp.202-206
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• 2000

까나리 액젓 부산물의 자원화를 위한 연구의 일환으로 까나리 액젓부산물을 건조, 분쇄하여 미생물 배지로의 활용 가능성을 조사하였다. 조사 균주로는 Escherichia coli$(Gram^-)$, Bacillus subtilis$(Gram^+)$ 발광미생물인 Photobacterium phosphoreum을 이용하였으며, 기준 LB 배지와 비교 분석하였다. 일반적으로 까나리 액젓부산물 배지는 E. coli나 B. subtilis와 같은 미생물에 필요한 일부 성분이 LB 배지에 비해 부족함을 보였다. 탄소원은 까나리 부산물 자체에 충분한 것으로 나타났으며, growth factor yeast extract 0.5%를 까나리 액젓부산물배지에 첨가하거나, 단백질원인 0.5% peptone과 0.3%의 yeast extract 혼합물을 보강한 까나리 액젓 부산물배지에서는 LB 배지와 같은 세포증식을 보였으며 각 까나리 액젓부산물배지의 제조단가는 LB 배지 조성단가의 46%, 19% 정도로 매우 저렴하였다. 또한 P. phosphoreum은 까나리 부산물 배지에 염과 glycerol을 첨가한 결과 생체발광을 보였다. 따라서 폐기 처분되고 있는 까나리 액젓부산물을 미생물배지로의 자원화와 환경오염문제를 해결할 수 있는 가능성을 제시하였다.