• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.443-449
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• 1988

Three yeast strains isolated from various sources were tested in its morphological, physiological, and biochemical characteristics. The results were compared with those of 35 standard yeast strains in order to study important taxonomical characteristics for yeast identification and to find out the problem of computer identifying system. Although few characteristics did not coincide with literature data, three unidentified strains were temporarily identified as Saccharomyces exiguus, Candida edax, and Candida membranaefactence. The use of computer identifying system must be accomponied with conventional identification method because of the restriction of data sources for computer system.

• The Korean Journal of Mycology
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• v.45 no.1
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• pp.23-30
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• 2017

Twenty-two yeast strains of 15 species were isolated from the leaves of 20 trees on Oknyeobong Peak, and 24 yeast strains of 12 species were isolated from the leaves of 20 trees on Yeonjasan Mountain in Daejeon city, Korea. Cryptococcus bestiolae (5 strains) and Aureobasidium pullulans (8 strains) were the predominant isolates from Oknyeobong Peak and Yeonjasan Mountain, respectively. Of a total of 46 yeast strains, Cryptococcus kuetzingii JSL508, Cryptococcus vishniacii JSL509, and Dioszegia takashimae JSL510 from Okyeobong Peak, and Plowrightia periclymeni JSL514, Erythrobasidium hasegawanium JSL0193, and Rhodotorula nothofagi JSL0196 from Yeonjasan Mountain were determined to be yeast strains that were yet unrecorded in Korea. Morphological and cultural characteristics of these unrecorded yeasts were investigated. Erythrobasidium hasegawanium JSL0193 and Rhodotorula nothofagi JSL0196 did not form ascospores and pseudomycelia. All the strains, except Dioszegia takashimae JSL510, were halotolerant or halophilic, and Cryptococcus kuetzingii JSL508 and Dioszegia takashimae JSL510 were thermophilic, growing at $37^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.25 no.5
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• pp.435-441
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• 1997

Forty seven strains of yeast were isolated from traditional Meju and were identified as Saccharomyces spp. (7 strains), Zygosaccharomyces spp. (7 strains), Kluyveromyces spp. and Hansenula spp. (each 5 strains), Rhodotorular spp. (8 strains), Candida spp. (12 strains), Pichia spp. and Debaryomyces spp. from results of their microbiological characteristics. The optimal medium for growth of all the yeasts was YM media and the optimal initial pH of the medium was 6.0. The optimum temperature for growth was 30$circ$ and among them, Sacch. exiguus OE-5, Sacch. cerevisiae OE-16, Sacch. kluyveri C-1 strains were thermotolerant yeasts which could grow at 40$circ$C.

• Journal of Life Science
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• v.6 no.2
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• pp.135-141
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• 1996

Possible yeast strains that could be used as feed for aquaculture were studied. It was shown that the maximum specific growth rate and the biomass yield of Kluyveromyces fragilis yeast and Candida utilis yeast under optimum pH and temperature were much higher than those of Saccharomyces cervisiae yeast which had been as established yeast diet for rotifer culture. Hence, this work was focussed on the growth characteristics of the two yeasts through flask dultures for mass production. With 5% inoculum dosage, the best values of $\mu$$_{max}$ and OD$_{max}$ were obtained with on 2.5% fructose medium and 2% YE medium for K. fragilis and C. utilis, respectively, where the values of $\mu$$_{max}$ and OD$_{max}$ were found to be 0.73 hr$^{-1}$ and 3.00 for K. fragilis and 0.59 hr$^{-1}$ and 2.80 for C. utilis. It was also found that the lag phase of the growth incresed with increasing initial zinc and NaCl concentrations and decreased with increasing inoculum dosage. Both yeasts could survive relatively well at 3.5% NaCl concentration, and only C. utilis yeast could utilize zinc.

• Journal of Microbiology and Biotechnology
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• v.17 no.2
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• pp.297-304
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• 2007

The effect of yeast propagated at different aeration conditions on yeast physiology, fermentation ability, and beer quality was investigated using three strains of Saccharomyces cerevisiae. It was shown that yeast cells grown under continuous aeration conditions during propagation were almost two times higher as compared with discontinuous aeration conditions. The maximum of cell growth of all samples reached between 36 hand 48 h. The concentration of trehalose was increased under continuous aerated yeasts, whereas glycogen was decreased. It was also observed that the concentration of glycogen and trehalose in yeast cells had no direct effect on subsequent fermentation ability. The effect of yeast propagated under different aeration conditions on subsequent fermentation ability was different from yeast strains, in which the influence will be most pronounced at the first fermentation. Later, the yeasts might regain its original characteristics in the following fermentations. Generally, continuously propagated yeast had a positive effect on beer quality in subsequent fermentation. Hence, the concentration of aroma compounds obtained with yeast propagated under 6 1/h for 48 h aeration was lower than those grown under other aeration conditions in the bottom yeasts; in particular, the amounts of phenylethyl alcohol, ester, and fatty acids were decreased.

• Food Science and Preservation
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• v.24 no.7
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• pp.1043-1051
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• 2017

Wild yeasts were isolated from domestic non-sterilized Makgeolli and their fermentation characteristics were analyzed to select the best fermentation seed culture. A total of 65 yeast strains isolated yeasts from non-sterilized Makgeolli and Nuruk. In order to select fermentable strains, hydrogen sulfide, $CO_2$ production ability, alcohol tolerance and aroma component production ability were analyzed. To screen the aromatic strains of isolates, media containing cerulenin, 5,5,5-trifluor-DL-leucine (TFL) and API ZYM kit were used. There were 36 strains resistance to cerulenin and all strains produced esterase and demonstrated tolerance against TFL. Hydrogen sulfide, which could degrade the quality of the fermented beverage, was not produced in 34 yeast. The correlation between alcohol tolerance of yeast and carbon dioxide production was analyzed by principal component analysis. YM22, YM31, YM32 and YM37 produced a total of 0.14-0.18 g/72 h of $CO_2$ indicating high fermentability. Alcohol tolerance was measured by alcohol concentration. YM32, YM37 yeast had 20% alcohol tolerance. As a result, alcohol and flavor characteristics of wild yeast isolated from non-sterilized Makgeolli were analyzed and it was confirmed that yeast was suitable for the production of alcohol.

• The Korean Journal of Mycology
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• v.20 no.3
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• pp.269-272
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• 1992

208 yeast strains were isolated from air at El-Minia city, Egypt. Using 22 morphologi cal and physiological merkmals, these strains were identified and assignned to eight species belonging to seven genera. Rhodotorula mucilaginosa and Cryptococcus albidus were the most dominant species followed by Debaryomyces hansenii. These yeast species occurred regularly, whereas other species appeared sporadically. Rh. rubra, Saccharomyces kluyveri and Rh. aurantiaca were also isolated from the sampled air. The results of this study showed that time, hight and area of air sampling affect composition and total counts of yeast microflora in the air.

• Microbiology and Biotechnology Letters
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• v.16 no.4
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• pp.265-269
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• 1988

For the purpose of developing new thermotolerant yeast strains for ethanol fermentation, yeasts were isolated from molasses and screened for their fermentation ability at elevated temperatures. Three candidate strains were screened. These strains preferred pH 5.0 and 34$^{\circ}C$ for their ethanol production. Under such conditions the three strains showed average ethanol productivity of 75g ethanol per liter of fermentation broth in n synthetic medium containing glucose as substrate. These strains were identified as Saccharomyces cerevisiae and Kluveromyces marxianus.

• Microbiology and Biotechnology Letters
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• v.28 no.6
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• pp.309-315
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• 2000

To isolate yeast strains producing high concentration of ethanol, 125 strains were subjected to screening. Initially 14 strains able to grow in a medium containing 15%(v/v) ethanol, 7 strains capable of growing in a medium containing 50%(v/v) glucose, 23 strains having relatively fast fermentation rates, 13 strains able to grow at $42^{\circ}C$ were selected. After secondary screening, 11 strains having relatively high ini-tial fermentation rate and producing high concentration of ethanol were selected. After tertiary screening 5 strains producing high concentration of ethanol were selected. These 5 strains were again for their ethanol produc-tion, residual sugar, and viability using fermentation medium containing 25% glucose. The strain producing the highest concentration of ethanol was 20-1 strain which produced 10.56%(v/v) ethanol in 4 days, and the highest viable strain was 11-1 which produced 10.35%(v/v) ethanol(13.1%. v/v) with the viability of 30.44% after 5 days of fermentation. Both of the 20-1 and 11-1 strains were identified as Saccharomyces cerevisiae.

• The Korean Journal of Mycology
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• v.45 no.1
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• pp.31-42
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• 2017

Several yeast strains were isolated from leaves collected from Mt. Daedun and Mt. Chilgap in Korea. A total of 79 strains of 32 species were isolated from 44 leaves obtained from Mt. Daedun. Cryptococcus spp., including Cryptococcus magnus, were found to be dominant, while 16 strains of Aureobasidium pullulans were isolated. Among the strains isolated from Mt. Daedun, Asterotremella humicola JSL502, Barnettozyma californica JSL503, Bullera unica JSL501, Bulleromyces albus JSL505, and Candida vaccinii JSL507 are considered rare yeast species in Korea. All of these rare strains, except for Bulleromyces albus JSL505, formed ascospores. Bullera unica JSL501 was able to grow in yeast extract-peptone-dextrose (YPD) medium containing 10% NaCl. Twenty-five yeast strains of 18 species were isolated from 43 leaves obtained from Mt. Chilgap. Six strains of Pseudozyma spp., including three strains of Pseudozyma aphidis, were isolated in the dormant state. Of these strains, the occurrence of Rhodotorula phylloplana JSL515, Rhodotorula pinicola JSL516, Schwanniomyces vanrijiae JSL517, and Sporisorium loudetiae JSL518 is rare in Korea. Only Sporisorium loudetiae JSL518 formed ascospores, while Rhodotorula pinicola JSL516 and Sporisorium loudetiae JSL518 formed pseudomycelia. The halophilic yeast Schwanniomyces vanrijiae JSL517 was isolated and observed to grow in YPD medium containing 5% NaCl.