• Title/Summary/Keyword: Xylose Fermentation

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Studies on the Ethanol Production by Clostridium thermosaccharolyticum (Clostridium thermosaccharolyticum에 의한 에탄올생산에 관한 연구)

  • 조은경;이윤광;변유량;유주현
    • Microbiology and Biotechnology Letters
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    • v.13 no.4
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    • pp.397-402
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    • 1985
  • The fermentation of various sugars by C. thermosaccharolyticum was examined under pH controlled, anaerobic condition. The kinetic model for Product formation at various sugars was the combination of growth and non-growth associated mode. In the utilization of a single sugar, glucose was the best carbon source for growth. The specific growth rate of glucose, xylose and cellobiose were 0.363 h$^{-1}$, 0.242 h$^{-1}$ and 0.144 h$^{-1}$ respectively. The production of ethanol from glucose showed a negatively growth associated mode, so the higher growth rate decreased the productivity of ethanol. The maximum concentrations of the produced ethanol were 2.42 g/l, 3.76 g/l, and 3.4 g/l on glucose, xylose, and cellobiose. No glucose was detected during cellobiose fermentation. Sequential utilization of sugars was observed in the mixtures of glucose, xylose and cellobiose. It preferred glucose, followed by xylose and then cellobiose. The presence of other sugars had little or no effect on the rate of another sugar utilization. Cell lysis at the end of fermentation occured more slowly in the mixtures of sugars than a single sugar.

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Lactic Acid Production from Xylose by Extractive Fermentation using ion-Exchange Resin (이온고환 수지를 이용한 Xylose로부터 젖산의 추출발효)

  • 김기복;신광순;권윤중
    • KSBB Journal
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    • v.17 no.6
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    • pp.566-570
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    • 2002
  • In lactic acid fermentation, the end product inhibition by lactic acid causes several problems. The most important of which are low lactate formation rate and its recovery from fermentation broth. To overcome these problems, extractive lactic acid fermentation was carried out in a bioreactor, which was connected to a column packed with anion exchange resin (Amberlite IRA-400, 250 g). The system was started as a batch process, and then the separation process was started when the lactic acid concentration reached 10 g/L, 20 g/L or 30 g/L. In each case, total lactic acid concentration was reached to 48.6, 53.6, 52.6 g/L with its productivity of 1.2 g/L $.$ h, 1.6 g/L $.$ h, and 1.3 g/L $.$ h, respectively Especially, in the case of the 20 g/L recycling-initiation process, extractive fermentation reduced tie fermentation time (17 hrs) by 34% in comparison with the conventional batch process. The direct consequence of this time reduction was shown by a 1.8 fold increase in overall lactic acid productivity.

The Changes of Hardness and Microstructure of Dongchimi according to Different Kinds of Sugar (당의 종류를 달리한 동치미의 경도 변화 및 세포벽 관찰)

  • Ahn, Gee-Jung
    • Culinary science and hospitality research
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    • v.12 no.4 s.31
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    • pp.299-319
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    • 2006
  • The purpose of this study was to investigate the changes of hardness and microstructure of Dongchimi cooked with various sources of sugar(xylitol, xylose, sugar, pear juice). It was fermented at $10^{\circ}C$ for 60 days. The changes of pH in Dongchimi used different kinds of sugar decreased in all samples during the fermentation period, and then showed a slow decrease after 12 days of fermentation. The total acidity of Dongchimi using xylitol arrived slowly at the best tasting condition($0.3\sim0.4$ point) compared with other conditions. The changes of salt content were showed high as compared with other test conditions in 0 day, the day of fermentation. At the early stage of fermentation, the changes of turbidity of Dongchimi using sugar, pear juice were showed high as compared with those of Dongchimi using xylitol, xylose for $5\sim15$ days of fermentation. The maximum cutting force of Chinese radish Dongchimi showed the highest value among al at the 25 th day of ripening and then decreased gradually. The maximum cutting force of Dongchimi using sugar showed the lowest. The calcium and magnesium contents of Dongchimi juice and Chinese radish Dongchimi juice using xylitol were observed high at the early stage of fermentation and showed the highest value during the fermentation period. The microstructure showed disintegration appearance of middle lamella and cell wall during the fermentation period.

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Cell Fusion Between Xylose Fermenting Yeast and Xylanase Secreting Yeast (Xylanase 분비효모와 Xylose 발효효모의 Protoplast Fusion)

  • 김남순;배명애;서정훈
    • Microbiology and Biotechnology Letters
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    • v.17 no.2
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    • pp.88-93
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    • 1989
  • To improve a new yeast strain capable of converting xylan to ethanol directly, we tried protoplast fusion between xylose fermenting yeast (Candida sp. X-6-41) and xylan assimilating yeast (Crypto-coccus sp. XB-33), finally selected the most promising two fusants (XFU-1 and XFU-2). As the optimum conditions for protoplast formation, the yeast cells were cultured to exponential phase in YPD and YPX containing 0.6M KCI, respectively, and then treated with zymolyase (0.25mg/$m\ell$), cellulase(4mg/$m\ell$) and 100mM 2-mercaptoethanol at pH 8 and 3$0^{\circ}C$. The protoplasts of parental auxotrophs were fused in the presence of 20mM CaCl$_2$and 40% polyethylene glycol(M.W.4000). The physiological and morphological characteristics of the fusants, such as assimilation of carbon sources, cell size, growth rate, xylanase activity and xylan fermentation ability were investigated. Xylanase activity of fusants that cultured in chemically minimal medium was higher than that of fusants that cultured in completed medium, because xylanase producing activity of xylose fermenting yeast(X-6-41) was inhibited by isoleucine.

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Production of Xylitol by Catabolite Derepressed Mutant of Candida sp. (Candida sp.의 Catabolite Derepressed Mutant에 의한 Xylitol 생산)

  • 한완옥;서진호;유연우
    • KSBB Journal
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    • v.13 no.1
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    • pp.6-12
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    • 1998
  • In order to produce xylitol from hemicellulose hydrolysate which is widely used as a substrate, the development of strain such as catabolite derepressed mutant is required. After treatment of Candida sp. with EMS, GM-17 and PM-34 as catabolite derepressed mutant were isolated from Candida guilliermondii and Candida parapsilosis, respectively. Mutant GM-17 and PM-34 simultaneously assimilated xylose and glucose during the fermentation. The specific xylose reductase and xylitol dehydrogenase activities of mutant strains were also higher than those of wild strains in glucose medium and mixed medium of glucose and xylose. The xylitol productivity and yield of mutant GM-17 and PM-34 were improved as compared to the wild types in the mixed medium. The xylitol productivity and yield of mutant GM-17 were 0.09 g/L·hr and 0.56 g-xylitol/g-xylose, and those of mutant PM-34 were 0.21 g/L·hr and 0.52 g-xylitol/g-xylose in the mixed medium, respectively.

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Effect of Different Pretreatment Methods on the Bioconversion of Rice Bran into Ethanol

  • Eyini, M.;Rajapandy, V.;Parani, K.;Lee, Min-Woong
    • Mycobiology
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    • v.32 no.4
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    • pp.170-172
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    • 2004
  • The efficiency of acid, enzyme and microbial pretreatment of rice bran was compared based on the content of cellulose, hemicellulose, reducing sugars and xylose in the substrate. An isolate of Aspergillus niger or a strain of Trichoderma viride(MTCC 800) was employed for microbial pretreatment of rice bran in solid state. Acid pretreatment resulted in the highest amount of reducing sugars followed by enzyme and microbial pretreatment. A. niger showed a higher rate of hydrolysis than T. viride. The rice bran hydrolysate obtained from the different methods was subsequently fermented to ethanol either by Zymomonas mobilis(NCIM 806) or by Pichia stipitis(NCIM 3497). P. stipitis fermentation resulted in higher ethanol(37% higher) and biomass production($76{\sim}83%$ higher) than those of Z. mobilis. Maximum ethanol production resulted at 12h in Zymomonas fermentation, while in Pichia fermentation, it was observed at 60h. Microbial pretreatment of rice bran by A. niger followed by fermentation employing P. stipitis was more efficient but slower than the other microbial pretreatment and fermentation.

Metabolic Engineering of Saccharomyces cerevisiae for Redox Balance of Xylose Fermentation

  • Kim, Soo Rin;Jin, Yong-Su
    • Current Research on Agriculture and Life Sciences
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    • v.32 no.4
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    • pp.199-202
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    • 2014
  • The bioconversion of cellulosic biomass hydrolyzates consisting mainly of glucose and xylose requires the use of engineered Saccharomyces cerevisiae expressing a heterologous xylose pathway. However, there is concern that a fungal xylose pathway consisting of NADPH-specific xylose reductase (XR) and $NAD^+$-specific xylitol dehydrogenase (XDH) may result in a cellular redox imbalance. However, the glycerol biosynthesis and glycerol degradation pathways of S. cerevisiae, termed here as the glycerol cycle, has the potential to balance the cofactor requirements for xylose metabolism, as it produces NADPH by consuming NADH at the expense of one mole of ATP. Therefore, this study tested if the glycerol cycle could improve the xylose metabolism of engineered S. cerevisiae by cofactor balancing, as predicted by an in-silico analysis using elementary flux mode (EFM). When the GPD1 gene, the first step of the glycerol cycle, was overexpressed in the XR/XDH-expressing S. cerevisiae, the glycerol production significantly increased, while the xylitol and ethanol yields became negligible. The reduced xylitol yield suggests that enough $NAD^+$ was supplied for XDH by the glycerol cycle. However, the GPD1 overexpression completely shifted the carbon flux from ethanol to glycerol. Thus, moderate expression of GPD1 may be necessary to achieve improved ethanol production through the cofactor balancing.

Effects of Xylose and Xylitol on the Organic Acid Fermentation of Kimchi (자일로스와 자일리톨 첨가가 김치의 유기산 발효에 미치는 영향)

  • Kim, Dong-Kyung;Kim, Sang-Yong;Lee, Jung-Kul;Noh, Bong-Soo
    • Korean Journal of Food Science and Technology
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    • v.32 no.4
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    • pp.889-895
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    • 2000
  • This study was conducted to investigate the utilization of xylose and xylitol on Lactobacillus species isolated from Kimchi and their effect on the pH, titratable acidity, microorganism and formation of organic acids in Kimchi during fermentation at $10^{\circ}C$. Five species among six Lactobacillus species isolated from Kimchi could not utilize medium with xylose. All the Lactobacillus species isolated from Kimchi could not utilize medium with xylitol. The pH of Kimchi samples were similar to that of control Kimchi. The titratable acidity of Kimchi with xylose or xylitol was lower than that of control. This agreed to the degree of formation of lactic acid during fermentation of Kimchi. Formation of lactic acid for Kimchi with xylitol was lower than those of others. Therefore, shelf-life of Kimchi with xylitol could be extended.

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Ethanol Fermentation of Hemicellulose Hydrolyzate Using High-Level Inocula of a Pachysolen tannophilus NRRL Y-2460 (Pachysolen tannophilus의 고동도 Inocula를 이용한 Hemicelluose hydrolyzate의 알코올 발효)

  • Chung, In-Sik;Hahn, Tae-Ryong
    • Applied Biological Chemistry
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    • v.30 no.4
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    • pp.311-314
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    • 1987
  • High-level yeast inocula was investigated as a means of overcoming the inhibition problem in ethanol fermentation of hemicellulose hydrolyzate. When the inoculum exceeded 25g dry cells/liter, the fermentation proceeded completely to the end within 24 hours. Furfural was taken up by Pachysolen tannophilus and catabolized to furfuryl alcohol. Thus inhibitory effect of furfural component was less adverse toward ethanol production than that of non-furfural components in hemicellulose hydrolyzate. The specific ethanol productivity in the fermentation of hemicellulose hydrolyzate was 14% of that of simulated media containing 41.8g xylose and 2.3g furfural per liter.

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Ethanol Fermentation of the Enzymatic Hydrolysates from the Products Pretreated using [EMIM]Ac and Its Co-Solvents with DMF

  • Han, Song-Yi;Park, Chan-Woo;Park, Jae-Bum;Ha, Suk-Jin;Kim, Nam-Hun;Lee, Seung-Hwan
    • Journal of Forest and Environmental Science
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    • v.36 no.1
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    • pp.62-66
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    • 2020
  • Ethanol fermentation of the enzymatic hydrolysates from the products pretreated using 1-ethyl-3-methyl-imidazolium acetate ([EMIM]Ac) and its co-solvents with dimethylformamide (DMF) was conducted using Saccharomyces cerevisiae (D452-2). The optical density change due to the yeast cell growth, the consumption amount of monosugars (glucose, xylose), the concentration of acetate, and ethanol production yield were investigated. The co-solvent system lowered inhibition of the growth of the cells. The highest concentration of glucose (7.8 g/L) and xylose (3.6 g/L) was obtained from the enzymatic hydrolysates of the pretreated product by pure [EMIM]Ac. The initial concentration of both monosugars in the enzymatic hydrolysates was decreased with increasing fermentation time. Ethanol of Approximately 3 g/L was produced from the enzymatic hydrolysates by pure [EMIM]Ac and co-solvent with less than 50% DMF.