• Journal of Microbiology and Biotechnology
• /
• 제20권4호
• /
• pp.767-774
• /
• 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
• /
• 제26권6호
• /
• pp.543-549
• /
• 2016

The objective of this study was to investigate quality properties of 'Cheonghyang' wine using different commercial yeast strains. Soluble solid content, pH level and total acidity of 'Cheonghyang' grape were $20^{\circ}Bx$, pH 3.5 and 0.66%, respectively. Total acidity ranged from 0.91~1.06% in the middle stage of fermentation and decreased to 0.77~0.82% when alcoholic fermentation finished. Alcohol content in wines ranged from 12.5% to 12.9% showing no significant difference in yeast strains. Wine fermented with Red Fruit had high volatile acid content (189.0 mg/L) whereas wine fermented with Fermivin indicated low volatile acid content (77.7 mg/L). Wines made with Montrachet, Fermivin and Aroma White had low brightness (L-value) compared to others. Results from sensory evaluation demonstrated that commercial wine yeasts, Montrachet and Fermivin, can be applied to improve sensory properties of 'Cheonghyang' wine such as aroma, acidity and transperency. On the other hand, preferences of wine fermented with EC-1118 strain containing lots of tannins and total polyphenols were significantly reduced.

• 한국식품조리과학회지
• /
• 제20권5호
• /
• pp.529-536
• /
• 2004

이에 본 연구에서는 시판 국내외산 효모 11종을 구입하여 발효특성 및 제빵성을 비교하여 효모 생산사업의 향상을 위한 기초자료를 제시하고자 하였다. 효모의 $CO_2$ 생성량, 반죽 팽창력, maltose 발효력 등을 측정하였고, 무당ㆍ저당ㆍ고당 반죽에 적용시켜 발효력 측정 및 실제 빵을 제조하여 관능평가를 실시하였다. 또한 배양한 효모의 maltase activity와 freeze tolerance rate를 측정하여 균주 특성을 비교하였다. 이 균주들은 동정하여 다음과 같은 결과를 얻었다. Meissle 발효관을 이용하여 시판 빵효모가 저당반죽에서 3시간 동안 $CO_2$를 생성한 양을 측정한 결과 Y7이 가장 높은 값을 나타냈고, Y5와 Y4가 그 뒤를 이었다. M-Cylinder를 이용하여 측정한 11종의 효모의 반죽 팽창력은 Y7, Y4,. Y5 등의 순으로 $CO_2$ 생성량을 측정한 결과와 일치하여 우수 균주로 Y7을 선별하여 이하의 실험에 이용하였다. ASF 합성배지에서의 maltose 발효 능력은 Y5, Y7, Y4 등의 순으로 나타나 $CO_2$ 생성량, 반죽 팽창력과는 약간의 차이가 있었다. 이때 선별된 Y7에 대해 비교 균주로 국내산 효모 K의 반죽종류에 따른 발효력을 비교한 결과 Y7이 K보다 무당, 저당 반죽에서 더욱 우수한 것으로 나타났다. Y7과 K를 이용하여 바게트(무당빵), 식빵(저당빵), 모닝롤(고당빵)을 제조한 후 빵의 품질을 측정한 결과 바게트에서는 K의 용적이 Y7보다 많이 부풀었으며, 비용적도 조금 더 높았다. 그러나, 식빵에서는 Y7의 용적이 K에 비해 더 많이 부풀었으며, 비용적도 더 높아서 Y7이 식빵 제조에 더 적합한 것으로 보였다. 모닝롤에서는 K와 Y7의 용적, 비용적이 매우 유사하여 두 균주가 모두 모닝롤 제조에 적합한 것으로 생각되었다. 또한 이 빵들을 이용하여 관능평가한 결과 바게트의 전반적인 기호도는 K와 Y7이 동점으로 유의적인 차이를 보이지 않았다. 식빵은 외상의 모든 항목과 색에서 K가 높은 점수를 얻었다. 모닝롤은 외상의 껍질 색, 질, 두 항목에서 K가 더 높은 점수를 얻으며 유의적인 차이를 보였고, 전반적인 기호도에서는 또한 유의적인 차이를 보이지 않았다.

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

• Journal of Microbiology and Biotechnology
• /
• 제24권4호
• /
• pp.497-506
• /
• 2014

In this study, crude glycerol was used as a carbon source in the cultivation of wild yeasts, aiming at the production of microbial lipids and citric acid. Forty yeasts of different sources were tested concerning their growth in crude and commercial glycerol. Four yeasts (Lindnera saturnus UFLA CES-Y677, Yarrowia lipolytica UFLA CM-Y9.4, Rhodotorula glutinis NCYC 2439, and Cryptococcus curvatus NCYC 476) were then selected owing to their ability to grow in pure ($OD_{600}$ 2.133, 1.633, 2.055, and 2.049, respectively) and crude ($OD_{600}$ 2.354, 1.753, 2.316, and 2.281, respectively) glycerol (10%, 20%, and 30%). Y. lipolytica UFLA CM-Y9.4 was selected for its ability to maintain cell viability in concentrations of 30% of crude glycerol, and high glycerol intake (18.907 g/l). This yeast was submitted to lipid production in 30 g/l of crude glycerol, and therefore obtained 63.4% of microbial lipids. In the fatty acid profile, there was a predominance of stearic (C18:0) and palmitic (C16:0) acids in the concentrations of 87.64% and 74.67%, respectively. We also performed optimization of the parameters for the production of citric acid, which yielded a production of 0.19 g/l of citric acid in optimum conditions (38.4 g/l of crude glycerol, agitation of 184 rpm, and temperature of $30^{\circ}C$). Yarrowia lipolytica UFLA CM-Y9.4 presented good lipid production when in the concentration of 30 g/l of glycerol. These data may be used for production in large quantities for the application of industrial biodiesel.

• 한국식품영양학회지
• /
• 제10권1호
• /
• pp.97-101
• /
• 1997

시판 간장이 유통되는 동안에 가스가 형성되어 품질을 저하시키는 문제가 발생되고 있어서 가스가 형성된 시판간장에서 효모를 분리하여 동정하였다. 가스가 발생된 시판간장에서 6개의 효모(SS-1, SS-2, SS-3, SS-4, SP-1, SP-2)를 분리하였는데, 그 중 3가지(SS-1, SS-2, SP-1) 효모는 막을 형성하였고, 나머지(SS-3, SS-4, SP-2) 효모는 막을 형성하지 않았다. 분리된 효모 중 SS-3을 제외하고는 간장에서 가스를 형성하였다. SS-3균주는 발효력이 약한 효모인 것 같다. SS-1, SS-2, SP-1는 Zygosaccharomyces rouxii var. halomembranis(산막효모)로 ss-4, sp-2는 Zygosaccharomyces rouxii(비산막 효모)로 동정되었고, SS-3는 Candida globosa(비산막 효모)로 동정되었다.

• Mycobiology
• /
• 제40권2호
• /
• pp.138-141
• /
• 2012

We measured physiological functionalities, including antihypertensive angiotensin I-converting enzyme inhibitory activity and immun-stimulating ${\beta}$-glucan content for sixty kinds of Makgeolli that is commercially available from the market. As a result, we selected R-12 commercial raw Makgeolli, with a high content of immuno-stimulating ${\beta}$-glucan, and R-14 commercial raw Makgeolli, exhibiting high antihypertensive activity. Due to the similarities in their overall physicochemical properties and raw materials used for fermentation, we compared the microbial flora in order to investigate the reason for the differences in their functionalities. Nested PCR and denaturing gradient gel electrophoresis for yeasts and bacteria were performed for analysis of microbial diversity of two different kinds of Makgeolli (i.e., R-12, R-14), which showed immuno-stimulating ${\beta}$-glucan content and exhibited a very high level of antihypertensive activity, respectively. Analysis of the 18S rDNA amplicon revealed a major presence of the yeast strain Pichia burtonii in every Makgeolli sample. Analysis of the 16S rDNA amplicon revealed a predominance of lactic acid bacteria, and the most frequent lactic acid bacteria were Lactobacillus ingluviei, L. fermentum, and L. harbinensis, and Lactobacillus sp. Among these, L. harbinensis was detected only in R-12 and L. ingluviei was found only in R-14. Different functionalities from the individual commercially available Makgeolli may be attributed to actions of different microbial flora during fermentation.

• Mycobiology
• /
• 제39권1호
• /
• pp.33-39
• /
• 2011

Wild yeasts on the surface of various fruits including grapes were surveyed to obtain yeast strains suitable for fermenting a novel wine with higher alcohol content and supplemented with rice starch. We considered selected characteristics, such as tolerance to alcohol and osmotic pressure, capability of utilizing maltose, and starch hydrolysis. Among 637 putative yeast isolates, 115 strains exhibiting better growth in yeast-peptone-dextrose broth containing 30% dextrose, 7% alcohol, or 2% maltose were selected, as well as five ${\alpha}$-amylase producers. Nucleotide sequence analysis of the 26S rDNA gene classified the strains into 13 species belonging to five genera; Pichia anomala was the most prevalent (41.7%), followed by Wickerhamomyces anomalus (19.2%), P. guilliermondii (15%), Candida spp. (5.8%), Kodamaea ohmeri (2.5%), and Metschnikowia spp. (2.5%). All of the ${\alpha}$-amylase producers were Aureobasidium pullulans. Only one isolate (NK28) was identified as Saccharomyces cerevisiae. NK28 had all of the desired properties for the purpose of this study, except ${\alpha}$-amylase production, and fermented alcohol better than commercial wine yeasts.

• 미생물학회지
• /
• 제12권1호
• /
• pp.31-36
• /
• 1974

Four strains of yeasts were chosen from those isolated previously, and a strain from 160 isolates collected in this year were examined for the treatment of pulp waste liquor. Experiments about optimum nutrient condition, composition of cells, and reduction of B.O.D. on the "S" pulp industry waste liquor were performed with 5 strains. 1. The isolates(strain 112) was identified as Candida utilis. 2. The optium concentration of 4 components of nutrients were ($NH_4$)$SO_2$lg/l, yeast extract 70mg/l, $KH_2PO_4$ 300mg/l, and $MgSO_4{\ddot}7H_2O$ 500mg/l. 3. Specific growth ratio of Candida utilis KYRI 112 was 0.48/hr at optimum nutrient media and the yield was 0.45%(V/V). 4. Endomycopsis capsularis KYRI 613 contained more crude protein than the most of commercial yeasts. 5. The B.O.D. of waste liquor was reduced ro 20% of its value by the culture.e culture.

• Journal of Microbiology and Biotechnology
• /
• 제32권3호
• /
• pp.307-316
• /
• 2022

Yeasts play an important role in spontaneous fermentation of traditional alcoholic beverages. Our previous study revealed that a mixed-consortia of both Saccharomyces and non-Saccharomyces yeasts were responsible for fermentation of khadi, a popular, non-standardized traditional beverage with an immense potential for commercialization in Botswana. Functional characterization of isolated fermenting yeasts from mixed consortia is an indispensable step towards the selection of potential starter cultures for commercialization of khadi. In this study, we report the characterization of 13 khadi isolates for the presence of brewing-relevant phenotypes such as their fermentative capacity, ability to utilize a range of carbon sources and their ability to withstand brewing-associated stresses, as a principal step towards selection of starter cultures. Khadi isolates such as Saccharomyces cerevisiae, Saccharomycodes ludwigii and Candida ethanolica showed good brewing credentials but Lachancea fermentati emerged as the isolate with the best brewing attributes with a potential as a starter culture. However, we were then prompted to investigate the potential of L. fermentati to influence the fruity aromatic flavor, characteristic of khadi. The aroma components of 18 khadi samples were extracted using headspace solid phase micro-extraction (HS-SPME) and identified using a GC-MS. We detected esters as the majority of volatile compounds in khadi, typical of the aromatic signature of both khadi and L. fermentati associated fermentations. This work shows that L. fermentati has potential for commercial production of khadi.