The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Akiyoshi Sakoda - One of the best experts on this subject based on the ideXlab platform.
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Structural changes of lignoCelluloses by a nonionic surfactant, Tween 20, and their effects on cellulase adsorption and saccharification.
Bioresource Technology, 2011Co-Authors: Hirotaka Fujita, Akiyoshi SakodaAbstract:Abstract In this work, we found that Tween 20 treatment (0–8 mM) contributed to the cell wall collapse of most samples except for those with high lignin contents and high crystallinity. Cell wall collapse contributed to the formation of 10- to 50-nm pores and not only increased the monolayer saturation amount of adsorbed cellulase about 3–3.6 times but also increased the cellulase adsorption rate (De/r2) about 160–880 times. Moreover, Cellulose Conversion at 72 h was also increased 8.7–21.5% by Tween 20 treatment. On the other hand, the adsorption of Tween 20 on Avicel (microcrystalline Cellulose) hindered the cellulase reaction (adsorption and saccharification). The effect of Tween 20 treatment on the crystalline part was insignificant for both lignoCelluloses and Avicel. It was found that some degree of pretreatment (e.g. lignin removal) that enhances Tween 20 diffusion into samples is necessary to obtain the structural effects of Tween 20.
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effects of a non ionic surfactant tween 20 on adsorption desorption of saccharification enzymes onto from lignoCelluloses and saccharification rate
Adsorption-journal of The International Adsorption Society, 2011Co-Authors: Dongjune Seo, Hirotaka Fujita, Akiyoshi SakodaAbstract:In this work, we examined the role of a non-ionic surfactant, Tween 20, on enzymatic hydrolysis of lignoCelluloses. Delignified lignoCelluloses (pine wood chip) were used as model substrates. Effects of Tween 20 on adsorption/desorption onto/from lignoCelluloses with and without hydrolysis were evaluated respectively. Tween 20 lowered the non-biospecific adsorption of β-glucosidase and enhanced the bio-specific adsorption of cellulase. Tween 20 did not affect the liquid phase reaction (cellobiose hydrolysis). However, for the solid surface reaction (Cellulose hydrolysis), Cellulose Conversion for 72 hrs was increased 9–21% and 1–8.5% for samples with high lignin contents (PI) and low lignin contents (PIII) by injection of Tween 20 (0.024–0.24 mM), respectively. Moreover, Tween 20 increased the Cellulose Conversion rate substantially. It is suggested that the increase of cellulase amount adsorbed due to the increase of effective Cellulose surface by Tween 20 contribute to the enhancement of Cellulose Conversion.
Charles E. Wyman - One of the best experts on this subject based on the ideXlab platform.
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Deactivation of Cellulase at the Air-Liquid Interface Is the Main Cause of Incomplete Cellulose Conversion at Low Enzyme Loadings
Scientific Reports, 2018Co-Authors: Samarthya Bhagia, Rachna Dhir, Rajeev Kumar, Charles E. WymanAbstract:Amphiphilic additives such as bovine serum albumin (BSA) and Tween have been used to improve Cellulose hydrolysis by cellulases. However, there has been a lack of clarity to explain their mechanism of action in enzymatic hydrolysis of pure or low-lignin cellulosic substrates. In this work, a commercial Trichoderma reesei enzyme preparation and the amphiphilic additives BSA and Tween 20 were applied for hydrolysis of pure Avicel Cellulose. The results showed that these additives only had large effects on Cellulose Conversion at low enzyme to substrate ratios when the reaction flasks were shaken. Furthermore, changes in the air-liquid interfacial area profoundly affected Cellulose Conversion, but surfactants reduced or prevented cellulase deactivation at the air-liquid interface. Not shaking the flasks or adding low amounts of surfactant resulted in near theoretical Cellulose Conversion at low enzyme loadings given enough reaction time. At low enzyme loadings, hydrolysis of Cellulose in lignocellulosic biomass with low lignin content suffered from enhanced enzyme deactivation at the air-liquid interface.
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Strong cellulase inhibition by Mannan polysaccharides in Cellulose Conversion to sugars.
Biotechnology and Bioengineering, 2014Co-Authors: Rajeev Kumar, Charles E. WymanAbstract:Cellulase enzymes contribute a major fraction of the total cost for biological Conversion of lignocellulosic biomass to fuels and chemicals. Although a several fold reduction in cellulase production costs and enhancement of cellulase activity and stability have been reported in recent years, sugar yields are still lower at low enzyme doses than desired commercially. We recently reported that hemicellu- lose xylan and its oligomers strongly inhibit cellulase and that supplementation of cellulase with xylanase and b-xylosidase would significantly reduce such inhibition. In this study, mannan polysaccharides and their enzymatically prepared hydrolyzates were discovered to be strongly inhibitory to fungal cellulase in Cellulose Conversion (>50% drop in % relative Conversion), even at a small concentration of 0.1g/L, and inhibition was much greater than experienced by other known inhibitors such as cellobiose, xylooligomers, and furfural. Furthermore, cellulase inhibition dramatically increased with heteromannan loading and mannan substitu- tion with galactose side units. In general, enzymatically prepared hydrolyzates were less inhibitory than their respective mannan polysaccharides except highly substituted ones. Supplementation of cellulase with commercial acces- sory enzymes such as xylanase, pectinase, and b-glucosidase was effective in greatly relieving inhibition but only for less substituted heteromannans. However, cellulase supplemen- tation with purified heteromannan specific enzymes relieved inhibition by these more substituted heteromannans as well, suggesting that commercial preparations need to have higher amounts of such activities to realize high sugar yields at the low enzyme protein loadings needed for low cost fuels production. Biotechnol. Bioeng. 2014;111: 1341-1353.
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carbohydrate derived pseudo lignin can retard Cellulose biological Conversion
Biotechnology and Bioengineering, 2013Co-Authors: Rajeev Kumar, Charles E. Wyman, Poulomi Sannigrahi, Seokwon Jung, Arthur J RagauskasAbstract:Dilute acid as well as water only (hydrothermal) pretreatments often lead to a significant hemiCellulose loss to soluble furans and insoluble degradation products, collectively termed as chars and/or pseudo-lignin. In order to understand the factors contributing to reducing sugar yields from pretreated biomass and the possible influence of hemiCellulose derived pseudo-lignin on Cellulose Conversion at the moderate to low enzyme loadings necessary for favorable economics, dilute acid pretreatment of Avicel Cellulose alone and mixed with beechwood xylan or xylose was performed at various severities. Following pretreatment, the solids were enzymatically hydrolyzed and characterized for chemical composition and physical properties by NMR, FT-IR, and SEM imaging. It was found that hemiCelluloses (xylan) derived-pseudo-lignin was formed at even moderate severities and that these insoluble degradation products can significantly retard Cellulose hydrolysis. Furthermore, although low severity (CSF ~ 1.94) dilute acid pretreatment of a xylan-Avicel mixture hydrolyzed most of the xylan (98%) and produced negligible amounts of pseudo-lignin, enzymatic Conversion of Cellulose dropped significantly (>25%) compared to Cellulose pretreated alone at the same conditions. The drop in Cellulose Conversion was higher than realized for cellulase inhibition by xylooligomers reported previously. Plausible mechanisms are discussed to explain the observed reductions in Cellulose Conversions.
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Carbohydrate derived-pseudo-lignin can retard Cellulose biological Conversion.
Biotechnology and Bioengineering, 2012Co-Authors: Rajeev Kumar, Poulomi Sannigrahi, Seokwon Jung, Arthur J Ragauskas, Charles E. WymanAbstract:Dilute acid as well as water only (hydrothermal) pretreatments often lead to a significant hemiCellulose loss to soluble furans and insoluble degradation products, collectively termed as chars and/or pseudo-lignin. In order to understand the factors contributing to reducing sugar yields from pretreated biomass and the possible influence of hemiCellulose derived pseudo-lignin on Cellulose Conversion at the moderate to low enzyme loadings necessary for favorable economics, dilute acid pretreatment of Avicel Cellulose alone and mixed with beechwood xylan or xylose was performed at various severities. Following pretreatment, the solids were enzymatically hydrolyzed and characterized for chemical composition and physical properties by NMR, FT-IR, and SEM imaging. It was found that hemiCelluloses (xylan) derived-pseudo-lignin was formed at even moderate severities and that these insoluble degradation products can significantly retard Cellulose hydrolysis. Furthermore, although low severity (CSF ∼ 1.94) dilute acid pretreatment of a xylan–Avicel mixture hydrolyzed most of the xylan (98%) and produced negligible amounts of pseudo-lignin, enzymatic Conversion of Cellulose dropped significantly (>25%) compared to Cellulose pretreated alone at the same conditions. The drop in Cellulose Conversion was higher than realized for cellulase inhibition by xylooligomers reported previously. Plausible mechanisms are discussed to explain the observed reductions in Cellulose Conversions. Biotechnol. Bioeng. 2013; 110: 737–753. © 2012 Wiley Periodicals, Inc.
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supplementation with xylanase and β xylosidase to reduce xylo oligomer and xylan inhibition of enzymatic hydrolysis of Cellulose and pretreated corn stover
Biotechnology for Biofuels, 2011Co-Authors: Qing Qing, Charles E. WymanAbstract:Background HemiCellulose is often credited with being one of the important physical barriers to enzymatic hydrolysis of Cellulose, and acts by blocking enzyme access to the Cellulose surface. In addition, our recent research has suggested that hemiCelluloses, particularly in the form of xylan and its oligomers, can more strongly inhibit cellulase activity than do glucose and cellobiose. Removal of hemiCelluloses or elimination of their negative effects can therefore become especially pivotal to achieving higher Cellulose Conversion with lower enzyme doses.
Hirotaka Fujita - One of the best experts on this subject based on the ideXlab platform.
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Structural changes of lignoCelluloses by a nonionic surfactant, Tween 20, and their effects on cellulase adsorption and saccharification.
Bioresource Technology, 2011Co-Authors: Hirotaka Fujita, Akiyoshi SakodaAbstract:Abstract In this work, we found that Tween 20 treatment (0–8 mM) contributed to the cell wall collapse of most samples except for those with high lignin contents and high crystallinity. Cell wall collapse contributed to the formation of 10- to 50-nm pores and not only increased the monolayer saturation amount of adsorbed cellulase about 3–3.6 times but also increased the cellulase adsorption rate (De/r2) about 160–880 times. Moreover, Cellulose Conversion at 72 h was also increased 8.7–21.5% by Tween 20 treatment. On the other hand, the adsorption of Tween 20 on Avicel (microcrystalline Cellulose) hindered the cellulase reaction (adsorption and saccharification). The effect of Tween 20 treatment on the crystalline part was insignificant for both lignoCelluloses and Avicel. It was found that some degree of pretreatment (e.g. lignin removal) that enhances Tween 20 diffusion into samples is necessary to obtain the structural effects of Tween 20.
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effects of a non ionic surfactant tween 20 on adsorption desorption of saccharification enzymes onto from lignoCelluloses and saccharification rate
Adsorption-journal of The International Adsorption Society, 2011Co-Authors: Dongjune Seo, Hirotaka Fujita, Akiyoshi SakodaAbstract:In this work, we examined the role of a non-ionic surfactant, Tween 20, on enzymatic hydrolysis of lignoCelluloses. Delignified lignoCelluloses (pine wood chip) were used as model substrates. Effects of Tween 20 on adsorption/desorption onto/from lignoCelluloses with and without hydrolysis were evaluated respectively. Tween 20 lowered the non-biospecific adsorption of β-glucosidase and enhanced the bio-specific adsorption of cellulase. Tween 20 did not affect the liquid phase reaction (cellobiose hydrolysis). However, for the solid surface reaction (Cellulose hydrolysis), Cellulose Conversion for 72 hrs was increased 9–21% and 1–8.5% for samples with high lignin contents (PI) and low lignin contents (PIII) by injection of Tween 20 (0.024–0.24 mM), respectively. Moreover, Tween 20 increased the Cellulose Conversion rate substantially. It is suggested that the increase of cellulase amount adsorbed due to the increase of effective Cellulose surface by Tween 20 contribute to the enhancement of Cellulose Conversion.
Atsushi Fukuoka - One of the best experts on this subject based on the ideXlab platform.
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Cellulose depolymerization over heterogeneous catalysts
Accounts of Chemical Research, 2018Co-Authors: Abhijit Shrotri, Hirokazu Kobayashi, Atsushi FukuokaAbstract:Cellulosic biomass is the largest source of renewable organic carbon on our planet. Cellulose accounts for 40–50 wt % of this lignoCellulose, and it is a feedstock for industrially important chemicals and fuels. The first step in Cellulose Conversion involves its depolymerization to glucose or to its hydrogenated product sorbitol. The hydrolysis of Cellulose to glucose by homogeneous mineral acids was the subject of research for almost a century. However, homogeneous acids have significant drawbacks and are neither economical nor environmentally friendly. In 2006, our group reported for the first time the ability of heterogeneous catalysts to depolymerize Cellulose through hydrolytic hydrogenation to produce sorbitol. Later, we reported the hydrolysis of Cellulose to glucose using carbon catalyst containing weakly acidic functional groups. Understanding the reaction between Cellulose and heterogeneous catalyst is a challenge as the reaction occurs between a solid substrate and a solid catalyst.In this Acc...
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transfer hydrogenation of Cellulose to sugar alcohols over supported ruthenium catalysts
Chemical Communications, 2011Co-Authors: Hirokazu Kobayashi, Hisateru Matsuhashi, Tasuku Komanoya, Kenji Hara, Atsushi FukuokaAbstract:Ru/C catalysts are active for the Conversion of Cellulose using 2-propanol or H2 of 0.8 MPa as sources of hydrogen, whereas the Ru/Al2O3 catalyst is inactive in both reactions, indicating that the Ru/C catalysts are remarkably effective for the Cellulose Conversion.
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Cellulose Conversion under heterogeneous catalysis.
ChemSusChem, 2008Co-Authors: Paresh L. Dhepe, Atsushi FukuokaAbstract:In view of current problems such as global warming, high oil prices, food crisis, stricter environmental laws, and other geopolitical scenarios surrounding the use of fossil feedstocks and edible resources, the efficient Conversion of Cellulose, a non-food biomass, into energy, fuels, and chemicals has received much attention. The application of heterogeneous catalysis could allow researchers to develop environmentally benign processes that lead to selective formation of value-added products from Cellulose under relatively mild conditions. This Minireview gives insight into the importance of biomass utilization, the current status of Cellulose Conversion, and further transformation of the primary products obtained.
Lee R Lynd - One of the best experts on this subject based on the ideXlab platform.
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Conversion for avicel and afex pretreated corn stover by clostridium thermocellum and simultaneous saccharification and fermentation insights into microbial Conversion of pretreated cellulosic biomass
Bioresource Technology, 2011Co-Authors: Xiongjun Shao, Anna Guseva, Venkatesh Balan, David A. Hogsett, Bruce E Dale, Lee R LyndAbstract:In this study, efforts were taken to compare solubilization of Avicel and AFEX pretreated corn stover (AFEX CS) by SSF and Clostridium thermocellum fermentation, with an aim to gain insights into microbial Conversion of pretreated cellulosic biomass. Solubilization rates for AFEX CS are comparable for the two systems while solubilization of Avicel is much faster by C. thermocellum. Initial catalyst loading impacts final Cellulose Conversion for SSF but not for C. thermocellum. Hydrolysis of the two substrates using cellfree C. thermocellum fermentation broth revealed much smaller difference in Cellulose Conversion than the difference observed for growing cultures. Tests on hemiCellulose removal and particle size reduction for AFEX CS indicated that substrate accessibility is very important for enhanced solubilization by C. thermocellum.
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quantification of cell and cellulase mass concentrations during anaerobic Cellulose fermentation development of an enzyme linked immunosorbent assay based method with application to clostridium thermocellum batch cultures
Analytical Chemistry, 2003Co-Authors: Yiheng Zhang, Lee R LyndAbstract:A methodology was developed to determine the mass concentrations of cellulase and cells applicable to studies of microbial Cellulose utilization in systems for which a substantial fraction of cellulase is cell-associated. Antibodies raised against a 14-amino acid synthetic peptide with sequence taken from the cohesin domain of the scaffoldin protein of Clostridium thermocellum ATCC 27405 were used to develop an indirect ELISA protocol. Six cellulase calibration standards were prepared using affinity digestion (Morag, E.; Bayer, E. A.; Lamed, R. Enzyme Microb. Technol. 1992, 14, 289−292.). These included supernatant and pellet samples from an Avicel-grown culture with fractional Cellulose Conversion (χ) = 0.98, as well as supernatant, pellet, cell-associated, and Cellulose-associated samples from an Avicel-grown culture with χ = 0.8. All six standards displayed a very similar absorbance versus concentration relationship when subjected to ELISA, essentially identical SDS−PAGE banding patterns, and similar c...