Ethanol Production Using Concentrated Oak Wood Hydrolysates and Methods to Detoxify
Biomass Research Team, Korea Institute of Energy Research, P.O. Box 5, Taedok Science Town, Taejon 305-343, Korea. Applied Biochemistry and Biotechnology
(Impact Factor: 1.74).
02/1999; 77-79(1-3):547-59. DOI: 10.1385/ABAB:78:1-3:547
Ethanol production from concentrated oak wood hydrolysate was carried out to obtain a high ethanol concentration and a high ethanol yield. The effect of added inhibitory compounds, which are typically produced in the pretreatment step of steam-explosion on ethanol fermentation, was also examined. p-Hydroxybenzoic aldehyde, a lignin-degradation product, was the most inhibitory compound tested in this study. Compounds with additional methyl groups had reduced toxicity and the aromatic acids were less toxic than the corresponding aldehydes. The lignin-degradation products were more inhibitory than the sugar-derived products, such as furfural and 5-hydroxymethylfurfural (HMF). Adaptation of yeast cells to the wood hydrolysate and detoxification methods, such as using charcoal and overlime, had some beneficial effects on ethanol production using the concentrated wood hydrolysate. After treatment with charcoal and low-temperature sterilization, the yeast cells could utilize the concentrated wood hydrolysate with 170 as well as 140 g/L glucose, and produce 69.9 and 74.2 g/L ethanol, respectively, with a yield of 0.46-0.48 g ethanol/g glucose. In contrast, the cells could not completely utilize untreated wood hydrolysate with 100 g/L glucose. Low-temperature sterilization, with or without charcoal treatment, was very effective for ethanol production when highly concentrated wood hydrolysates were used. Low-temperature sterilization has advantages over traditional detoxification methods, such as using overlime, ion exchange, and charcoal, because of the reduction in the total cost of ethanol production.
Available from: Asmita Prabhune
- "furfural, acetic acid and lignin derivatives (Carvalho et al. 2004a; Silva et al. 2005). These inhibitory compounds affect the ability of yeast to ferment sugars in hydrolysates, and thus to improve microbial production of ethanol from lignocellulosic hydrolysates, different detoxification methods like pH adjustment (Eken-Saraçoglu and Arslan 2000; Martinez et al. 2001), activated charcoal adsorption (Lee et al. 1999; Mussatto and Roberto 2001), and ion exchange resin adsorption (Carvalho et al. 2004b; Villarreal et al. 2006) have been proposed. "
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ABSTRACT: A new xylose fermenting yeast was isolated from over-ripe banana by enrichment in xylose-containing medium. The phylogenetic analysis of ITS1-5.8S-ITS2 region sequences of ribosomal RNA of isolate BY2 revealed that it shows affiliation to genus Pichia and clades with Pichia caribbica. In batch fermentation, Pichia strain BY2 fermented xylose, producing 15 g l−1 ethanol from 30 g l−1 xylose under shaking conditions at 28°C, with ethanol yield of 0.5 g g−1 and volumetric productivity of 0.31 g l−1 h−1. The optimum pH range for ethanol production from xylose by Pichia strain BY2 was 5–7. Pichia strain BY2 also produced 6.08 g l−1 ethanol from 30 g l−1 arabinose. Pichia strain BY2 can utilize sugarcane bagasse hemicellulose acid hydrolysate for alcohol production, efficiency of fermentation was improved by neutralization, and sequential use of activated charcoal adsorption method. Percent total sugar utilized and ethanol yield for the untreated hydrolysate was 17.14% w/v and 0.33 g g−1, respectively, compared with 66.79% w/v and 0.45 g g−1, respectively, for treated hemicellulose acid hydrolysate. This new yeast isolate showed ethanol yield of 0.45 g g−1 and volumetric productivity of 0.33 g l−1 h−1 from sugarcane bagasse hemicellulose hydrolysate detoxified by neutralization and activated charcoal treatment, and has potential application in practical process of ethanol production from lignocellulosic hydrolysate.
Annals of Microbiology 03/2012; 63(1). DOI:10.1007/s13213-012-0445-4 · 0.99 Impact Factor
Available from: Jian Xu
- "d Assuming 7% (w/v) ethanol produced from fermentation in a CBP system (Lynd et al., 2008). e Lee et al. (1999). f Larsson et al. (2000). "
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ABSTRACT: The cellulosome, a multi-subunit protein complex catalyzing cellulose degradation in cellulolytic Clostridium thermocellum, plays a crucial role in Consolidated Bioprocessing (CBP) of lignocellulose into ethanol. Here, activity of cellulosome was tested under varying concentrations of chemical compounds derived from lignocellulose pretreatment and fermentation. We found that, firstly, the cellulolytic activity of cellulosome was actually promoted by formate, acetate and lactate; secondly, cellulosome was tolerant up to 5mM furfural, 50mM p-hydroxybenzoic acid and 1mM catechol. Furthermore, the cellulosome exhibited higher ethanol tolerance and thermostability than commercialized fungal (Trichoderma reesei) cellulase. To probe the implication of these unique enzyme-features, C. thermocellum JYT01 was cultured under conditions optimal for cellulosome activity. This CBP system yielded 491 mM ethanol, the highest level reported thus far for C. thermocellum monocultures. These findings demonstrate the potential advantages of bacterial cellulosome, and provide a novel strategy for design, selection and optimization of the cellulosome-ethanologen partnership.
Bioresource Technology 12/2010; 101(24):9560-9. DOI:10.1016/j.biortech.2010.07.065 · 4.49 Impact Factor
Available from: Solange I Mussatto
- "Very often hydrolysates containing toxic substances have to be purified before they can be used as fermentation media . To overcome the inhibitory effect of the toxic compounds during fermentation by yeasts, several types of treatment have been employed, including microorganism adaptation  , evaporation  , overtitration and overliming  , and adsorption on ion-exchange resins  , or on activated charcoal  . Combinations of these treatments are also reported in the literature    "
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ABSTRACT: Rice straw hemicellulosic hydrolysate containing a high xylose concentration was used as fermentation medium to evaluate the kinetic behavior of Candida guilliermondii yeast (FTI 20037) during the bioconversion of xylose into xylitol. Assays were conducted first with detoxified and non-detoxified (raw) hydrolysates and semi-synthetic medium in agitated flasks, and second with detoxified hydrolysate in a stirred-tank bioreactor at a given oxygen transfer rate. The results for the agitated flasks showed that in detoxified hydrolysate the xylose-to-xylitol bioconversion by the yeast was as effective as in synthetic medium and 47% higher than in raw hydrolysate. In the stirred-tank bioreactor, the kinetic behavior of the yeast in detoxified hydrolysate was slower, resulting in smaller values of fermentative parameters, probably due to unsuitability of the oxygen transfer rate employed (KLa=22 h−1).
PROCESS BIOCHEMISTRY 07/2004; 39(11-39):1433-1439. DOI:10.1016/S0032-9592(03)00261-9 · 2.52 Impact Factor
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