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Mohammad J. Taherzadeh - One of the best experts on this subject based on the ideXlab platform.
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bioethanol production from sweet sorghum bagasse by mucor hiemalis
Industrial Crops and Products, 2011Co-Authors: Amir Goshadrou, Keikhosro Karimi, Mohammad J. TaherzadehAbstract:The present work deals with production of ethanol from sweet sorghum bagasse by a zygomycetes fungus Mucor hiemalis. The bagasse was treated with phosphoric acid and sodium hydroxide, with or without ultrasonication, prior to enzymatic hydrolysis by commercial cellulase and β-glucosidase enzymes. The phosphoric acid pretreatment was performed at 50 °C for 30 min, while the alkali treatment performed with 12% NaOH at 0 °C for 3 h. The pretreatments resulted in improving the subsequent enzymatic hydrolysis to 79–92% of the theoretical yield. The best hydrolysis performance was obtained after pretreatment by NaOH assisted with ultrasonication. The fungus showed promising results in fermentation of the Hydrolyzates. In the best case, the Hydrolyzate of NaOH-ultrasound pretreated bagasse followed by 24 h fermentation resulted in about 81% of the corresponding theoretical ethanol yield. Furthermore, the highest volumetric ethanol productivity was observed in the Hydrolyzates of NaOH pretreated bagasse, especially after ultrasonication in pretreatment stage.
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ethanol from oil palm empty fruit bunch via dilute acid hydrolysis and fermentation by mucor indicus and saccharomyces cerevisiae
Agricultural Journal, 2011Co-Authors: Ria Millati, Mohammad J. Taherzadeh, Rachma Wikandari, Elisabeth Titik Trihandayani, Muhammad Nur Cahyanto, Claes NiklassonAbstract:Oil Palm Empty Fruit Bunch (OPEFB) was hydrolyzed in a one-stage hydrolysis using dilute-sulfuric acid (0.2, 0.8%) at 170-230°C with a holding time of 5 and 15 min. The maximum yield of xylose was 135.94 g kg-1 OPEFB, obtained at 0.8% acid, 190°C and 5 min. The maximum yield of glucose was 62.70 g kg-1 OPEFB, obtained at 0.8% acid, 210°C and 5 min. Based on these results, two-stage hydrolysis was performed to produce Hydrolyzates for the fermentation process. Hydrolyzate from the first stage was fermented by Mucor indicus while the Hydrolyzate from the second stage was fermented by Saccharomyces cerevisiae. The corresponding ethanol yields were 0.45 and 0.46 g ethanol g-1 sugar consumed.
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a possible industrial solution to ferment lignocellulosic Hydrolyzate to ethanol continuous cultivation with flocculating yeast
International Journal of Molecular Sciences, 2007Co-Authors: Ronny Purwadi, Tomas Brandberg, Mohammad J. TaherzadehAbstract:The cultivation of toxic lignocellulosic hydrolyzat es has become a challenging research topic in recent decades. Although several cultivation methods have been proposed, numerous questions have arisen regarding their indu strial applications. The current work deals with a solution to this problem which has a g ood potential application on an industrial scale. A toxic dilute-acid Hydrolyzate w as continuously cultivated using a high- cell-density flocculating yeast in a single and ser ial bioreactor which was equipped with a settler to recycle the cells back to the bioreactor s. No prior detoxification was necessary to cultivate the Hydrolyzates, as the flocks were able to detoxify it in situ . The experiments were successfully carried out at dilution rates up to 0.52 h -1 . The cell concentration inside the bioreactors was between 23 and 35 g-DW/L, while the concentration in the effluent of the settlers was 0.32 ± 0.05 g-DW/L. An ethanol yield of 0.42-0.46 g/g-consumed sugar was achieved, and the residual sugar concentration was less than 6% of the initial fermentable sugar (glucose, galactose and mannose) of 35.2 g/L.
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Fed-batch cultivation of Mucor indicus in dilute-acid lignocellulosic Hydrolyzate for ethanol production.
Biotechnology letters, 2005Co-Authors: Keikhosro Karimi, Tomas Brandberg, Lars Edebo, Mohammad J. TaherzadehAbstract:Mucor indicus fermented dilute-acid lignocellulosic Hydrolyzates to ethanol in fed-batch cultivation with complete hexose utilization and partial uptake of xylose. The fungus was tolerant to the inhibitors present in the Hydrolyzates. It grew in media containing furfural (1 g/l), hydroxymethylfurfural (1 g/l), vanillin (1 g/l), or acetic acid (7 g/l), but did not germinate directly in the Hydrolyzate. However, with fed-batch methodology, after initial growth of M. indicus in 500 ml enzymatic wheat Hydrolyzate, lignocellulosic Hydrolyzate was fermented with feeding rates 55 and 100 ml/h. The fungus consumed more than 46% of the initial xylose, while less than half of this xylose was excreted in the form of xylitol. The ethanol yield was 0.43 g/g total consumed sugar, and reached the maximum concentration of 19.6 g ethanol/l at the end of feeding phase. Filamentous growth, which is regarded as the main obstacle to large-scale cultivation of M. indicus, was avoided in the fed-batch experiments.
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On-line estimation of sugar concentration for control of fed-batch fermentation of lignocellulosic Hydrolyzates by Saccharomyces cerevisiae.
Bioprocess and biosystems engineering, 2002Co-Authors: Anneli Nilsson, Mohammad J. Taherzadeh, Gunnar LidénAbstract:A feed control strategy, based on estimated sugar concentrations, was developed with the purpose of avoiding severe inhibition of the yeast Saccharomyces cerevisiae during fermentation of spruce Hydrolyzate. The sum of the fermentable hexose sugars, glucose and mannose, was estimated from on-line measurements of carbon dioxide evolution rate and biomass concentration by use of a simple stoichiometric model. The feed rate of the Hydrolyzate was controlled to maintain constant sugar concentration during fed-batch fermentation, and the effect of different set-point concentrations was investigated using both untreated and detoxified Hydrolyzates. The fed-batch cultivations were evaluated with respect to cellular physiology in terms of the specific ethanol productivities, ethanol yields, and viability of the yeast. The simple stoichiometric model used resulted in a good agreement between estimated sugar concentrations and off-line determinations of sugar concentrations. Furthermore, the control strategy used made it possible to maintain a constant sugar concentration without major oscillations in the feed rate or the sugar concentration. For untreated Hydrolyzates the average ethanol productivity could be increased by more than 130% compared to batch fermentation. The average ethanol productivity was increased from 0.12 to 0.28 g/g h. The productivity also increased for detoxified Hydrolyzates, where an increase of 16% was found (from 0.50 to 0.58 g/g h).
Gunnar Lidén - One of the best experts on this subject based on the ideXlab platform.
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On-line estimation of sugar concentration for control of fed-batch fermentation of lignocellulosic Hydrolyzates by Saccharomyces cerevisiae.
Bioprocess and biosystems engineering, 2002Co-Authors: Anneli Nilsson, Mohammad J. Taherzadeh, Gunnar LidénAbstract:A feed control strategy, based on estimated sugar concentrations, was developed with the purpose of avoiding severe inhibition of the yeast Saccharomyces cerevisiae during fermentation of spruce Hydrolyzate. The sum of the fermentable hexose sugars, glucose and mannose, was estimated from on-line measurements of carbon dioxide evolution rate and biomass concentration by use of a simple stoichiometric model. The feed rate of the Hydrolyzate was controlled to maintain constant sugar concentration during fed-batch fermentation, and the effect of different set-point concentrations was investigated using both untreated and detoxified Hydrolyzates. The fed-batch cultivations were evaluated with respect to cellular physiology in terms of the specific ethanol productivities, ethanol yields, and viability of the yeast. The simple stoichiometric model used resulted in a good agreement between estimated sugar concentrations and off-line determinations of sugar concentrations. Furthermore, the control strategy used made it possible to maintain a constant sugar concentration without major oscillations in the feed rate or the sugar concentration. For untreated Hydrolyzates the average ethanol productivity could be increased by more than 130% compared to batch fermentation. The average ethanol productivity was increased from 0.12 to 0.28 g/g h. The productivity also increased for detoxified Hydrolyzates, where an increase of 16% was found (from 0.50 to 0.58 g/g h).
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Use of dynamic step response for control of fed-batch conversion of lignocellulosic Hydrolyzates to ethanol.
Journal of biotechnology, 2001Co-Authors: Anneli Nilsson, Mohammad J. Taherzadeh, Gunnar LidénAbstract:Optimization of fed-batch conversion of lignocellulosic Hydrolyzates by the yeast Saccharomyces cerevisiae was studied. The feed rate was controlled using a step response strategy, in which the carbon dioxide evolution rate was used as input variable. The performance of the control strategy was examined using both an untreated and a detoxified dilute acid Hydrolyzate, and the performance was compared to that obtained with a synthetic medium. In batch cultivation of the untreated Hydrolyzate, only 23% of the hexose sugars were assimilated. However, by using the feed-back controlled fed-batch technique, it was possible to obtain complete conversion of the hexose sugars. Furthermore, the maximal specific ethanol productivity (q(t.max)) increased more than 10-fold, from 0.06 to 0.70 g g(-1) h(-1). In addition, the viability of the yeast cells decreased by more than 99% in batch cultivation, whereas a viability of more than 40% could be maintained during fed-batch cultivation. In contrast to untreated Hydrolyzate, it was possible to convert the sugars in the detoxified Hydrolyzate also in batch cultivation. However, a 50% higher specific ethanol productivity was obtained using fed-batch cultivation. During batch cultivation of both untreated and detoxified Hydrolyzate a gradual decrease in specific ethanol productivity was observed. This decrease could largely be avoided in fed-batch cultivations. (C) 2001 Elsevier Science B.V. All rights reserved. (Less)
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Characterization and fermentation of dilute-acid Hydrolyzates from wood
Industrial & Engineering Chemistry Research, 1997Co-Authors: Mohammad J. Taherzadeh, Robert Eklund, Lena Gustafsson, Claes Niklasson, Gunnar LidénAbstract:Dilute-acid Hydrolyzates from alder, aspen, birch, willow, pine, and spruce were fermented without prior detoxification. The Hydrolyzates were prepared by a one-stage hydrolysis process using sulfuric acid (5 g/L) at temperatures between 188 and 234 C and with a holding time of 7 min. The fermentations were carried out anaerobically by Saccharomyces cerevisiae (10 g of d.w./L) at a temperature of 30 C and an initial pH of 5.5. The fermentabilities were quite different for the different wood species, and only Hydrolyzates of spruce produced at 188 and 198 C, Hydrolyzates of pine produced at 188 C, and Hydrolyzates of willow produced at 198 C could be completely fermented within 24 h. From the sum of the concentrations of the known inhibitors furfural and 5-(hydroxymethyl)furfural (HMF), a good prediction of the maximum ethanol production rate could be obtained, regardless of the origin of the Hydrolyzate. Furthermore, in Hydrolyzates that fermented well, furfural and HMF were found to be taken up and converted by the yeast, concomitant with the uptake of glucose.
Arland T. Hotchkiss - One of the best experts on this subject based on the ideXlab platform.
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molecular and functional properties of a xylanase hydrolysate of corn bran arabinoxylan
Carbohydrate Polymers, 2018Co-Authors: Madhuvanti S Kale, Hoa K Chau, Madhav P. Yadav, Arland T. HotchkissAbstract:Abstract Enzymatic hydrolysis of arabinoxylans to prepare arabinoxylo-oligosaccharides has been of high interest from the commercial point of view. However, some arabinoxylans, such as those extracted from corn bran, tend to be difficult to hydrolyze into oligosaccharides due to their highly branched structure which limits the action of xylanases. This research presents a new arabinoxylo-oligosaccharide preparation by enzymatic treatment of corn bran with an endoxylanase enzyme. The native arabinoxylan had a molecular weight of 253 kDa and the hydrolysate polymers ranged from 51.6 to 132 kDa. The Hydrolyzates showed improved solubility in contrast to the original sample. The molecular properties of the Hydrolyzates were related to the enzyme concentration used in the hydrolysis process, with increasing enzyme concentration leading to decreasing molecular weight and size. Solution viscosity of the samples also decreased with increasing enzyme concentration. All of the Hydrolyzates showed emulsifying ability that was comparable to the original arabinoxylan.
Zbigniew Adamski - One of the best experts on this subject based on the ideXlab platform.
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recovery of chromium iii from wastes of uncolored chromium leathers part ii solvent extraction of chromium iii from alkaline protein Hydrolyzate
Separation and Purification Technology, 2011Co-Authors: Barbara Wionczyk, Wieslaw Apostoluk, Witold A Charewicz, Zbigniew AdamskiAbstract:Abstract Experimental studies were made on the solvent extraction of chromium(III) with Aliquat 336 from the protein Hydrolyzate obtained by the alkaline hydrolysis of wastes of uncolored chromium-tanned leathers. The effects of NaOH concentration in the protein Hydrolyzate, contact time of the organic and aqueous phases, the aqueous/organic phase volume ratio, and temperature on the extraction of chromium(III) and collagen proteins/peptides were examined. Stripping of chromium(III) from the loaded organic phase is also presented. Chromium(III) can be efficiently removed (99%) from the alkaline Hydrolyzate by the solvent extraction with Aliquat 336 after 60–90 min at temperature 50 °C and at the aqueous/organic phase volume ratio equal to 5/1. Moreover, it was found that during one cycle of the alkaline hydrolysis followed by the extraction and stripping operations, chromium(III) can be separated from the source leather wastes with the total yield over 90%. The final products are: the protein Hydrolyzates contaminated with traces of Cr(III) (less than 5 ppm) and the solutions of chromium(III) sulfate containing small quantities of protein substances.
Michael A Cotta - One of the best experts on this subject based on the ideXlab platform.
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comparative lipid production by oleaginous yeasts in Hydrolyzates of lignocellulosic biomass and process strategy for high titers
Biotechnology and Bioengineering, 2016Co-Authors: Patricia J Slininger, Stephanie R Thompson, Bruce S Dien, Cletus P Kurtzman, Venkatesh Balan, Michael A Cotta, Bryan R Moser, Erica L Bakota, Patricia J Obryan, Mingjie JinAbstract:Oleaginous yeasts can convert sugars to lipids with fatty acid profiles similar to those of vegetable oils, making them attractive for production of biodiesel. Lignocellulosic biomass is an attractive source of sugars for yeast lipid production because it is abundant, potentially low cost, and renewable. However, lignocellulosic Hydrolyzates are laden with byproducts which inhibit microbial growth and metabolism. With the goal of identifying oleaginous yeast strains able to convert plant biomass to lipids, we screened 32 strains from the ARS Culture Collection, Peoria, IL to identify four robust strains able to produce high lipid concentrations from both acid and base-pretreated biomass. The screening was arranged in two tiers using undetoxified enzyme Hydrolyzates of ammonia fiber expansion (AFEX)-pretreated cornstover as the primary screening medium and acid-pretreated switch grass as the secondary screening medium applied to strains passing the primary screen. Hydrolyzates were prepared at ∼18–20% solids loading to provide ∼110 g/L sugars at ∼56:39:5 mass ratio glucose:xylose:arabinose. A two stage process boosting the molar C:N ratio from 60 to well above 400 in undetoxified switchgrass Hydrolyzate was optimized with respect to nitrogen source, C:N, and carbon loading. Using this process three strains were able to consume acetic acid and nearly all available sugars to accumulate 50–65% of cell biomass as lipid (w/w), to produce 25–30 g/L lipid at 0.12–0.22 g/L/h and 0.13–0.15 g/g or 39–45% of the theoretical yield at pH 6 and 7, a performance unprecedented in lignocellulosic Hydrolyzates. Three of the top strains have not previously been reported for the bioconversion of lignocellulose to lipids. The successful identification and development of top-performing lipid-producing yeast in lignocellulose Hydrolyzates is expected to advance the economic feasibility of high quality biodiesel and jet fuels from renewable biomass, expanding the market potential for lignocellulose-derived fuels beyond ethanol for automobiles to the entire U.S. transportation market. Biotechnol. Bioeng. 2016;113: 1676–1690. © 2016 Wiley Periodicals, Inc.
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evolved strains of scheffersomyces stipitis achieving high ethanol productivity on acid and base pretreated biomass Hydrolyzate at high solids loading
Biotechnology for Biofuels, 2015Co-Authors: Patricia J Slininger, Maureen A Sheaandersh, Stephanie R Thompson, Bruce S Dien, Cletus P Kurtzman, Venkatesh Balan, Leonardo Da Costa Sousa, Nirmal Uppugundla, Bruce E Dale, Michael A CottaAbstract:Lignocellulosic biomass is an abundant, renewable feedstock useful for the production of fuel-grade ethanol via the processing steps of pretreatment, enzyme hydrolysis, and microbial fermentation. Traditional industrial yeasts do not ferment xylose and are not able to grow, survive, or ferment in concentrated Hydrolyzates that contain enough sugar to support economical ethanol recovery since they are laden with toxic byproducts generated during pretreatment. Repetitive culturing in two types of concentrated Hydrolyzates was applied along with ethanol-challenged xylose-fed continuous culture to force targeted evolution of the native pentose fermenting yeast Scheffersomyces (Pichia) stipitis strain NRRL Y-7124 maintained in the ARS Culture Collection, Peoria, IL. Isolates collected from various enriched populations were screened and ranked based on relative xylose uptake rate and ethanol yield. Ranking on Hydrolyzates with and without nutritional supplementation was used to identify those isolates with best performance across diverse conditions. Robust S. stipitis strains adapted to perform very well in enzyme Hydrolyzates of high solids loading ammonia fiber expansion-pretreated corn stover (18% weight per volume solids) and dilute sulfuric acid-pretreated switchgrass (20% w/v solids) were obtained. Improved features include reduced initial lag phase preceding growth, significantly enhanced fermentation rates, improved ethanol tolerance and yield, reduced diauxic lag during glucose-xylose transition, and ability to accumulate >40 g/L ethanol in <167 h when fermenting Hydrolyzate at low initial cell density of 0.5 absorbance units and pH 5 to 6.
