• Journal of Microbiology and Biotechnology
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• 제19권6호
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• pp.547-555
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• 2009

Nanoscopic changes in the cell surface morphology of the yeasts Saccharomyces cerevisiae (strain NCYC 1681) and Schizosaccharomyces pombe (strain DVPB 1354), due to their exposure to varying concentrations of hydrogen peroxide (oxidative stress), were investigated using an atomic force microscope (AFM). Increasing hydrogen peroxide concentration led to a decrease in cell viabilities and mean cell volumes, and an increase in the surface roughness of the yeasts. In addition, AFM studies revealed that oxidative stress caused cell compression in both S. cerevisiae and Schiz. pombe cells and an increase in the number of aged yeasts. These results confirmed the importance and usefulness of AFM in investigating the morphology of stressed microbial cells at the nanoscale. The results also provided novel information on the relative oxidative stress tolerance of S. cerevisiae and Schizo pombe.

• 한국식품영양과학회지
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• 제27권2호
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• pp.232-238
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• 1998

To developed natural food preservatives, ethanol and water extracts were prepared from the defatted camellia(Camellia japonica L.) seeds. Antimicrobial activities were examined against 14 microorganisms which were food borne pathogens and/or food poisoning microorganisms and food-related bacteria and yeasts. Ethanol extract showed antimicrobial activities against several microorganisms tested, but not on lactic acid bactria. Especially, minimum inhibitory concentrations(MIC) for yeasts were as low as 1mg/ml. Water extract exhibited antimicrobial activities for the yeasts tested, but almost bacteria were not observed. The ethanol extract was fractionated in the order of hexane, chloroform, ethylaetate and butanol fractions to test antimicrobial activity. The strongest activity for the tested yeasts were found in the butanol fractions, but bacteria were chloroform fraction. Hansenula anomala treated with ethanol were observed by scanning electron micrograph, and the results exhibited morphological changes, including the irregularly contracted cell surface and expanded ellipsoidal shape.

• 한국균학회지
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• 제46권4호
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• pp.447-457
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• 2018

In this paper, the screening of potent acetylcholinesterase (AChE) inhibitor - producing yeasts from wild yeasts and the condition for the production of anti-dementia AChE inhibitors are described. Among one hundred and seven non-pathogenic wild yeast strains from the waters and soils of three main rivers in Daejeon metropolitan city and midstream of Yeongsangang river in Sangju, sporogenous Saccharomyces cerevisiae WJSL0113 and asporogenous Wickerhamomyces anomalus JSF0128 were selected as useful strains for the production of potent AChE inhibitors. The AChE inhibitors of S. cerevisiae WJSL0113 and W. anomalus JSF0128 had a maximum yield when they were incubated in yeast extract-peptone-dextrose media (pH 6.0 in S. cerevisiae WJSL0113 and pH 5.0 in W. anomalus JSF0128) for 18 hr at $30^{\circ}C$, respectively.

• 유기물자원화
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• 제4권1호
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• pp.1-11
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• 1996

음식물 쓰레기의 고온 퇴비화 과정에서 종균 첨가가 미생물의 변화에 미치는 영향을 조사하였다. 실험실용 소형 퇴비화 장치에 선발한 고온성 세균, 효모 및 고온성 세균, 효모 복합종균을 첨가하여 $50^{\circ}C$에서 분해시키면서 고온성 세균과 효모의 생육 및 pH의 변화를 측정한 결과, 모든 실험구에서 효모가 우선적으로 생육하였으며 고온성 세균은 그보다 1일 또는 2일 후에 생육하였다. 종균으로 고온성 세균만 사용한 경우는 효과가 거의 없었으나 고온성 세균과 효모의 복합 종균을 첨가한 경우에는 고온성 세균의 생육이 현저히 촉진되었다. 특히 효모 종균을 단독으로 첨가한 경우에도 고온성 세균의 수가 반응 시작부터 급속히 증가하였다. 이러한 결과는 음식물 쓰레기의 분해시 고온성 세균의 증식에는 효모의 역할이 필수적인 것으로 나타났으며 그 이유는 효모가 세균의 생육을 저해하는 유기산을 제거하기 때문으로 밝혀졌다.

• 미생물학회지
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• 제11권4호
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• pp.157-166
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• 1973

Fermented feed using rice, barley, wheat, and defatted rice brans as the raw materials were prepared by 3 species of wild yeasts which were selected among 35 strains of yeasts isolated, and their analytical values were examined. The results were as follows : 1. The three yeasts were identified as H.amomala var. anomala (No.225), Candida utilis (No.400), and Irpex-cellulase(consors) (no.403-A). 2. The optimum pH, and sugar concentration of these yeasts in liquid culture were pH 5.0 and Bllg. 10.deg. each. The optimum temperature was 30.deg.C for No.225 and No.403-A, 25.deg.C for No.400. The No.225 and No.403-A grow at higher temperature than 37.deg.C and 40.deg.C each. 3. The No.225 yeast had a large vegetative cell and strong sugar fermentability. The No.225 and 403-A could assimilate cellobiose, xylose, $KNO_2$ and $KNO_3$. These properties were fit for bran fermentation. 4. The No.403-A microorganism was a yeast-like microbe and showed cellulase activity which might help the propagation of other yeasts on the brans. 5. The analytical data of fermented feed indicated the following order of usable value ; rice-wheat-barley bran 4:4:2, rice-wheat bran 5:5, rice-barley bran 5:5, rice-defatted rice bran 5:5. 6. the fermented feed were prepared by mixing brans, 0.3% ammonium sulfate and 5%(w/w) inoculum of yeast suspension in 4% glucose solution. Water content 70-80%, fermentation temperature 25-30.deg.C, and fermentation time 2-3 days were given. 7. The rice-wheat bran 5:5 and rice-barley bran 5:5 fermented feed showed 11, 17-11.45% protein increase, and the rice-barley-wheat bran 4:4:2 and rice-defatted bran 5:5 showed 3.75-6.03% protein increase. 8. The fermented feed prepared in this experiment by the author might work as a nutritive feed using microbial cell body, enzymes produced by microbes and other microbial cell constituents.

• 한국균학회지
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• 제44권2호
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• pp.108-112
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• 2016

우리나라 토양 중의 효모 종 다양성 조사의 일환으로 서울특별시 H동 허브공원 일대 토양 29점을 2015년 5월에 수집하여 9종 15균주의 야생효모들을 polymerase chain reaction 을 이용한 internal transcribed spacer 부위와 26S rDNA의 D1/D2 부위의 염기서열 상동성 비교법을 이용하여 분리, 동정하였다. 이들 가운데 Cryptococcus laurentii 2균주를 포함하는 Cryptococcus속 균이 8균주로 가장 많이 분리되었고 Saccharomyces cerevisiae도 2균주 분리되었다. 이들 가운데 아직까지 우리나라 미생물 관련 학술지에 보고되지 않은 Candida boleticola SU14-2와 Candida novakii SU6-2, Cryptococcus podzolicus SU18-2 등의 미기록 효모들을 선별한 후 이들의 미생물학적 특성을 조사한 결과 Candida novakii SU6-2는 자낭포자와 의균사를 형성하였고 Candida boleticola SU14-2는 5% NaCl을 함유한 YPD 배지에서 생육하는 호염성 효모이었다.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.767-774
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• 2010

In this study, the problems of high caloric content, increased maturation time, and off-flavors in commercial beer manufacture arising from residual sugar, diacetyl, and acetaldehyde levels were addressed. A recombinant industrial brewing yeast strain (TQ1) was generated from T1 [Lipomyces starkeyi dextranase gene (LSD1) introduced, ${\alpha}$-acetohydroxyacid synthase gene (ILV2) disrupted] by introducing Saccharomyces cerevisiae glucoamylase (SGA1) and a strong promoter (PGK1), while disrupting the gene coding alcohol dehydrogenase (ADH2). The highest glucoamylase activity for TQ1 was 93.26 U/ml compared with host strain T1 (12.36 U/ml) and wild-type industrial yeast strain YSF5 (10.39 U/ml), respectively. European Brewery Convention (EBC) tube fermentation tests comparing the fermentation broths of TQ1 with T1 and YSF5 showed that the real extracts were reduced by 15.79% and 22.47%; the main residual maltotriose concentrations were reduced by 13.75% and 18.82%; the caloric contents were reduced by 27.18 and 35.39 calories per 12 oz. Owing to the disruption of the ADH2 gene in TQ1, the off-flavor acetaldehyde concentrations in the fermentation broth were 9.43% and 13.28%, respectively, lower than that of T1 and YSF5. No heterologous DNA sequences or drug resistance genes were introduced into TQ1. Hence, the gene manipulations in this work properly solved the addressed problems in commercial beer manufacture.

• 동아시아식생활학회지
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• 제11권5호
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• pp.393-399
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• 2001

본 연구는 김치를 제조한 후 2$0^{\circ}C$에서 발효, 숙성시키면서 발효기간별로 효모를 순수 분리하여 동정하였으며, 동정된 10종의 균주에 대해서 4종의 소금과 3가지 소금 농도(0, 3.0 및 5.0%)에서 효모의 생육도를 조사하였다. 동정된 균주는 Saccharomyces cerevisia, Sporobolomyces albo-rubescens, Issatchenkia orientalis Cryptococcus luteolous, Ustilago maydis, Candida humilis, Pichia onychis, Cadida nitratophila, and Pichia jadinii. 이었으며, 김치 숙성 10일 이후에는 산막효모로 알려진 Pichia, Candida 등이 주를 이루었다. 소금 농도에 따른 효모의 생육도에서는 염농도가 증가할수록 생육이 저하되었으나, 발효 초기에 분리된 Issatchenkia orientals는 내염성 효모로 5% 염농도에서도 생육이 크게 저해되지 않았다. 효모 균종에서는 Cryptococcus sp. 와 Candida sp.가 소금 농도의 증가에 따라 생육이 크게 저해되었다. 4종류의 소금 모두 발효 초기에 분리된 균주의 경우 유도기가 짧았고, 균의 증식이 빠르게 진행된 반면, 김치 숙성 10일 이후에 분리된 균주는 염농도가 증가되면서 유도기가 연장되었으며, 또한 소금 종류 중 죽염이 효모의 생육을 가장 크게 저해하였고, 그 다음으로 재제염이었다.

• 한국식품조리과학회지
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• 제31권1호
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• pp.1-8
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• 2015

Organic acids are known as natural sanitizers. We examined the sanitizing effects of five organic acids (acetic acid, propionic acid, citric acid, malic acid, and lactic acid) and their persistence on three pectinolytic yeast strains isolated from decayed citrus, and the persistence of their sanitizing effects was determined during storage at $4^{\circ}C$ and $16^{\circ}C$. The 7~8 log CFU/mL of the mixed three yeast mixture was exposed to various concentrations of each organic acid for 1 min. The yeast mixtures decreased under detection limit(1 log CFU/mL) in 1% of acetic acid, followed by in 3% of propionic acid with the reduction of 5 log CFU/mL. The citric acid, malic acid, and lactic acid decreased the number of yeasts under detection limit at 7.5%. When treated with deionized water and 1~5% of organic acids were treated on the surfaces of citrus contaminated by yeasts, total numbers of the yeasts decreased under detection limit(3 log CFU) at 5% of acetic acid and 4 log CFU/piece at 5% propionic acid compared with deionized water. When treated with acetic acid and propionic acid on the stem ends of the contaminated citrus, total numbers of the yeasts significantly decreased 0.5 log CFU/piece at 3% of both organic acids. During storage at $4^{\circ}C$ and $16^{\circ}C$ for 20 days, total number of yeasts significantly decreased at 2% acetic acid compared with deionized water. This study suggested that organic acids could be used to sanitize microbial contaminants from citrus for storage and transportation.

• 한국균학회지
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• 제44권4호
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• pp.350-354
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• 2016

우리나라 주요 강 담수와 주변 토양 중의 야생효모 분포특성을 조사하고자 먼저 낙동강과 영산강 일부지역의 담수와 주변 토양 25점을 수집하여 15균주 9종의 야생효모들을 PCR을 이용한 ITS 부위와 26S rDNA의 D1/D2 부위의 염기서열 상동성 비교법을 이용하여 동정하였다. 이들 가운데 Aureobasidium pullulans와 Cryptococcus besiolae가 각각 3균주로 가장 많이 분리되었고, Lachancea thermotolerans와 Wickerhamomyces anomalus도 각각 2주씩 분리되었다. 특히 Candida ghanaensis와 Meira geulakonigii는 국내 처음 보고되는 미기록 균주들로서 포자를 형성하였고, YPD 배지와 potatoes dextrose 배지 등에서 잘 생육하는 특성을 갖고 있었다. 또한 두 미기록 효모들은 5% NaCl을 함유한 YPD 배지에서 생육하는 내염성 효모들이었다.