• Title, Summary, Keyword: Fermenting strains

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Screening and Characterization of Thermotolerant Alcohol-producing Yeast

  • Sohn, Ho-Yong
    • Journal of Microbiology and Biotechnology
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    • v.4 no.3
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    • pp.215-221
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    • 1994
  • Two strains of yeast (RA-74-2 and RA-912) showing superior fermenting ability at a high temperature were isolated from soils and wastewaters by an enrichment culture method. Based on the morphological and physiological charateristics, the two strains were identified as Saccharomyces cerevisiae and Kluyveromyces marxianus, respectively. RA-74-2 was able to grow upto $43^{\circ}C$ and sustain similar fermenting ability in the temperatures range from 30 to $40^{\circ}C$. In addition, the sugar- and ethanol-tolerance of RA-74-2 were 30% (w/v) glucose and 10% (v/v) ethanol, which appeared to be higher than those of nine other industrial yeast strains currently being used in the alcohol factories. The thermotolerant ethanol fermenting yeast RA-912 showed identical growth in the temperatures range from 35 to $45^{\circ}C$ and was resistant to various heavy metals. The quality and quantity of byproducts of the isolated yeast strains in fermentation broth after fermentation at $40^{\circ}C$ and $45^{\circ}C$ were similiar with those obtained at $30^{\circ}C$. These results show that RA-74-2 can be adopted for the ethanol fermentation process where the expenses for cooling system is significant, and suggest that RA-912 may be applied in either SSF(simultaneous saccharification and fermentation) or Flash-fermentation process and RA-912 may be used as a gene donor for the development of thermotolerant ethanol-fermenting yeasts.

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Screening and Characterization of Potential Bacillus Starter Cultures for Fermenting Low-Salt Soybean Paste (Doenjang)

  • Jeon, Hye Hee;Jung, Ji Young;Chun, Byung-Hee;Kim, Myoung-Dong;Baek, Seong Yeol;Moon, Ji Young;Yeo, Soo-Hwan;Jeon, Che Ok
    • Journal of Microbiology and Biotechnology
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    • v.26 no.4
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    • pp.666-674
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    • 2016
  • The bacterial strains were screened as potential starters for fermenting low-salt doenjang (a Korean traditional fermented soybean paste) using Korean doenjang based on proteolytic and antipathogenic activities under 6.5-7.5% NaCl conditions. Phylogenetic analysis based on 16S rRNA gene sequences showed that they all belonged to the genus Bacillus. Proteolytic and antipathogenic activities against Escherichia coli, Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, and Aspergillus flavus, as well as fibrinolytic, amylase, and cellulase activities of the 10 strains were quantitatively evaluated. Of these, strains D2-2, JJ-D34, and D12-5 were selected, based on their activities. The functional, phenotypic, and safety-related characteristics of these three strains were additionally investigated and strains D2-2 and D12-5, which lacked antibiotic resistance, were finally selected. Strains D2-2 and D12-5 produced poly-γ-glutamic acid and showed various enzyme activities, including α-glucosidase and β-glucosidase. Growth properties of strains D2-2 and D12-5 included wide temperature and pH ranges, growth in up to 16% NaCl, and weak anaerobic growth, suggesting that they facilitate low-salt doenjang fermentation. Strains D2-2 and D12-5 were not hemolytic, carried no toxin genes, and did not produce biogenic amines. These results suggest that strains D2-2 and D12-5 can serve as appropriate starter cultures for fermenting low-salt doenjang with high quality and safety.

Studies on the Selection of Microorganism for Food Wastes and Optimization of Fermentation Process (음식물찌꺼기 소멸효율 재고를 위한 발효균 및 발효 공정 최적화 연구)

  • Kim, Young-Kwon;Hong, Myung-Pyo;Kim, Myung-Jin;Hong, Suk-Il;Park, Myung-Suk;Kim, Jong-Suk;Chang, Ho-Geun
    • Journal of the Korea Organic Resources Recycling Association
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    • v.6 no.2
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    • pp.95-112
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    • 1998
  • For the effective disposal of organic food wastes, we seleted 4 strains of microorganism from 186 microbial candidate via enzyme activity test, salt tolerance, food decomposition rate, stability and safety of strains. The identity of these 4 strains are as follows : Fungi is Rhizopus sp., yeasts are Galactomyces sp., Pichia sp. and Hyphopichia sp., In the 50L fermenter scale, we tested various fermenting factor for the optimization of conditions of food waste decomposition using 4 selected strains. The optimum fomenting conditions were as follows : BIO-CHIP Volume 25-30 L, BIO CHIP size 2.0-6.0mm, air flow 200-280L/min, mixing intensity 2-4rpm, temperature $30-45^{\circ}C$. In these fermenting conditions, the efficiency of decomposition(rate of weight loss of food wastes) were 93%. Also the quality of fermenting output were assayed at the basis of fertilizer, and the results were as good as general compost.

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Evaluation of Ethanol Production Activity by Engineered Saccharomyces cerevisiae Fermenting Cellobiose through the Phosphorolytic Pathway in Simultaneous Saccharification and Fermentation of Cellulose

  • Lee, Won-Heong;Jin, Yong-Su
    • Journal of Microbiology and Biotechnology
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    • v.27 no.9
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    • pp.1649-1656
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    • 2017
  • In simultaneous saccharification and fermentation (SSF) for production of cellulosic biofuels, engineered Saccharomyces cerevisiae capable of fermenting cellobiose has provided several benefits, such as lower enzyme costs and faster fermentation rate compared with wild-type S. cerevisiae fermenting glucose. In this study, the effects of an alternative intracellular cellobiose utilization pathway-a phosphorolytic pathway based on a mutant cellodextrin transporter (CDT-1 (F213L)) and cellobiose phosphorylase (SdCBP)-was investigated by comparing with a hydrolytic pathway based on the same transporter and an intracellular ${\beta}$-glucosidase (GH1-1) for their SSF performances under various conditions. Whereas the phosphorolytic and hydrolytic cellobiose-fermenting S. cerevisiae strains performed similarly under the anoxic SSF conditions, the hydrolytic S. cerevisiae performed slightly better than the phosphorolytic S. cerevisiae under the microaerobic SSF conditions. Nonetheless, the phosphorolytic S. cerevisiae expressing the mutant CDT-1 showed better ethanol production than the glucose-fermenting S. cerevisiae with an extracellular ${\beta}$-glucosidase, regardless of SSF conditions. These results clearly prove that introduction of the intracellular cellobiose metabolic pathway into yeast can be effective on cellulosic ethanol production in SSF. They also demonstrate that enhancement of cellobiose transport activity in engineered yeast is the most important factor affecting the efficiency of SSF of cellulose.

Optimum Alcohol Fermenting Conditions for Kiwi (Actinidia chinensis) Wine

  • Jang, Se-Young;Woo, Seung-Mi;Kim, Ok-Mi;Choi, In-Wook;Jeong, Yong-Jin
    • Food Science and Biotechnology
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    • v.16 no.4
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    • pp.526-530
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    • 2007
  • The objective of this study was to establish the optimum alcohol fermenting conditions for the processing of kiwi wine and vinegar products. Six yeast strains were examined for their alcohol production from kiwi at $30^{\circ}C$ for 72 hr with continuous shaking at 100 rpm. Under these conditions, Saccharomyces kluyveri DJ97 produced the highest alcohol content of 10.2%. As the fermentation time extended to 96 hr, the alcohol content reached a maximum of 12.75%. The optimum alcohol fermenting conditions for kiwi fruit were accomplished when kiwi was added to an equal amount of water, inoculated with S. kluyveri DJ97 and fermented at $30^{\circ}C$ for 96 hr with continuous shaking. The content of soluble solids decreased as the alcohol concentration increased, whereas little change was observed in the pH and titratable acidity during the low temperature aging process. Other alcoholic compounds, such as methanol, isopropanol, n-propanol, isobutanol, and isoamylalcohol, tended to increase as fermentation progressed.

Isolation, Identification, and Characterization of Bacillus spp. from the Traditionally fermented Cheonggukjangs in the Gyeonggi and the Gangwon Provinces (경기.강원 지역의 전통발효 청국장으로부터 Bacillus균주의 분리 동정 및 특성 분석)

  • Lee, Nam-Keun;Jeon, Eun-Hee;Lee, Hyo-Jin;Cho, Il-Jae;Hahm, Young-Tae
    • Applied Biological Chemistry
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    • v.49 no.4
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    • pp.276-280
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    • 2006
  • Traditionally fermented Cheonggukjangs were collected from Gyeonggi and Gangwon provinces and 22 strains were isolated and identified by using 165 rDNA sequences. Most of the identified strains were Bacillus subtilis and B. licheniformis, B. subtilis and B. licheniformis are dominant in the Gyeonggi area and B. licheniformis in the Gangwon area. In the growth pattern of the isolated strains, the duration of lag phase was generally 5 to 7 hours and stationary phase was reached after 23 to 40 hours of incubation. Total cell populations at the stationary phase were between $1{\times}10^6\;CFU/ml$ and $5{\times}10^7\;CFU/ml$. The fermenting ability of carbohydrates of isolates showed some differences among the regions. The isolated strains from Yong-In, Gyeonggi showed higher fermenting abilities with D-xylose, xylitol, D-tagatose and Methyl-$\alpha$-D-mannopyranoside. D-lactose, D-tagatose, D-xylose, Methyl-$\alpha$-D-mannopyranoside, amygdalin, arbutin, esculin and 2-keto-gluconate were well fermented with the An-Seong's strains; L-rhamnose, inositol, D-mannitol, D-sorbitol, celibiose and gluconate with the Kawang-Ju's stains; and D-lactose with the Odaesan's strains.

Isolation and Identification of Korean type Streptococcus mutans (한국형 Streptococcus mutans의 분리 및 동정)

  • 현성희;장성렬;최영길
    • Korean Journal of Microbiology
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    • v.27 no.3
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    • pp.250-258
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    • 1989
  • S. mutans known as a causative causative agent of dental caries was isolated from a carious lesion of Korean in the present study. The physiological, biochemical characteristics and polysaccharide pattern of these isolates were compated with those of four laboratory strains ; AHT(a), FA-1F(b), LM7(e), and OMZ65(g). One hundred strains of oral streptococci were isolated from dental caries sites of Korean (one male and one female). Among these, 3 strains were identified as S. mutans. These strains were able to grow on selective media MS, MST, MSP, MSP1, MSB, MSBT and were stained dark pink when sprayed with solutions of mannitol and TTC. So, these strains were called strain 108, 110, and 120, respectively. Strain 108, 110, and 120 were bacitracin resistnt. As these strains contained particularly hippurate hydrolysis enzyme, they were distinguished from laboratory strains. Apart from laboratory strains, the strain 108 was not capable of fermenting lactose, the strain 110 was not able to ferment sorbitol, inulin, melibiose, raffinose and the strain120 was incapable of fermenting inulin, raffinose. All fractions of extracellular and ecll bound polysaccharide of the strain108, 110, and 120 were consisted of more glucan than fructan. Aside from laboratory strains, the isolated strains were composed of more water-insoluble glucans related adherence on solid surface than water-soluble. According to these results, the strain108, 110, and 120 had native characteristecs of S. mutans, but they were different from laboratory strains in some characteristics. Therefore, each of them was given a name to S. mutans KHC108, KHC110, and KHC120, respcetively.

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Yeast Cloning Vectors and their Application to the Development of Starch-fermenting Yeast (효모 Cloning Vector와 전분발효 효모의 개발)

  • Kim, Keun
    • Applied Biological Chemistry
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    • v.31 no.3
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    • pp.267-273
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    • 1988
  • Transformed, hybrid strains of the yeast Saccharomyces capable of simultaneous secretion of both glucoamylase and ${\alpha}-amylase$ have been produced. These strains can carry out direct, one-step assimilation of starch with conversion efficiency greater than 93% during a 5 day growth period. One of the transformants converts 92.8% of available starch into reducing sugars in only 2 days. Glucoamylase secretion by these strains results from expression of one or more chromosomal STA genes derived from Saccharomyces diastaticus. The strains were transformed by a plasmid(pMS12) containing mouse salivary ${\alpha}-amylase$ cDNA in an expression vector containing yeast alcohol dehydrogenase promoter and a segment of yeast $2{\mu}$ plasmid. The major starch hydrolysis product produced by crude amylases found in culture broths is glucose, indicating that ${\alpha}-amylase$ and glucoamylase act cooperatively.

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Studies on the wild yeasts in Korea (II) (한국산 야생효모에 관한 연구 2)

  • 박명삼;라철호
    • Korean Journal of Microbiology
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    • v.8 no.3
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    • pp.95-102
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    • 1970
  • From the crops Drosophila collected in Mt. Sokni and Mt.Kyeryong, 7 strains were isolated and then 6 species of wild yeast were identified. 1) Of these six species of wild yeasts two were to be of genus Saccharomyces(Ascosporgenous), two Torulopsis and two Trichosporon (both genuses of Asporogenous). 2) It was found that the fermentation of the wild yeasts isolated from Drosophila was much better than that of any others ; in particular, S. florentinus and S. cerevisiae were good in fermenting maltose. 3) After being cultivated in malt extract agar medium at $25^{\circ}C$ for 3 days, the vegetative cells were found to be big but Torulopsis cells small. 4) It was also observed that the species of yeasts used fro food by Drosophila largely depends on genus and species of Drophila. 5) Of the yeasts isolated from the Drosophila, Trichosporon capitatum and Torulopsis dattila, which has not previously been recorded, were identified. 6) It is believed, therfore, that S.florentinus, powerful in fermenting maltose, will be extremely useful in terms of industrial application.

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Isolation of a Fermenting Microorganism Involved in Formation of ortho-Dihydroxyisoflavones in Doenjang (Korean Fermented Soybean Paste)

  • Seo, Hyo-Seel;Lee, Jae-Hwan;Kwon, Dae-Yong;Park, Jin-Byung
    • Food Science and Biotechnology
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    • v.18 no.4
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    • pp.1030-1034
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    • 2009
  • A fermenting microorganism involved in formation of ortho-dihydroxyisoflavones (ODIs) during aging of doenjang (Korean fermented soybean paste) has been investigated. Microorganisms in ODI-containing doenjang were isolated by cultivating on yeast mold (YM) agar medium containing 0-7% NaCl. ODI formation of the isolated strains was examined by gas chromatography/mass spectrometry (GC/MS) analysis after cultivation in modified YM broth or soybean extract medium. An ODI-producing microbe was identified as Bacillus subtilis HS-1 based on 16S rRNA gene sequence analysis. The strain has produced 8-hydroxydaidzein as a major product during growth in the modified YM broth or soybean extract medium. Therefore, it was concluded that one of the microorganisms involved in the formation of ODIs in doenjang was B. subtilis HS-1.