The Experts below are selected from a list of 10062 Experts worldwide ranked by ideXlab platform
Charles E. Wyman - One of the best experts on this subject based on the ideXlab platform.
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review continuous hydrolysis and fermentation for Cellulosic ethanol production
Bioresource Technology, 2010Co-Authors: Simone Brethauer, Charles E. WymanAbstract:Ethanol made biologically from a variety of Cellulosic Biomass sources such as agricultural and forestry residues, grasses, and fast growing wood is widely recognized as a unique sustainable liquid transportation fuel with powerful economic, environmental, and strategic attributes, but production costs must be competitive for these benefits to be realized. Continuous hydrolysis and fermentation processes offer important potential advantages in reducing costs, but little has been done on continuous processing of Cellulosic Biomass to ethanol. As shown in this review, some continuous fermentations are now employed for commercial ethanol production from cane sugar and corn to take advantage of higher volumetric productivity, reduced labor costs, and reduced vessel down time for cleaning and filling. On the other hand, these systems are more susceptible to microbial contamination and require more sophisticated operations. Despite the latter challenges, continuous processes could be even more important to reducing the costs of overcoming the recalcitrance of Cellulosic Biomass, the primary obstacle to low cost fuels, through improving the effectiveness of utilizing expensive enzymes. In addition, continuous processing could be very beneficial in adapting fermentative organisms to the wide range of inhibitors generated during Biomass pretreatment or its acid catalyzed hydrolysis. If sugar generation rates can be increased, the high cell densities in a continuous system could enable higher productivities and yields than in batch fermentations.
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engineering of a high throughput screening system to identify Cellulosic Biomass pretreatments and enzyme formulations that enhance sugar release
Biotechnology and Bioengineering, 2010Co-Authors: Michael H Studer, Simone Brethauer, Jaclyn D Demartini, Heather L Mckenzie, Charles E. WymanAbstract:The recalcitrance of Cellulosic Biomass, theonly abundant, sustainable feedstock for making liquid fuels, is a primary obstacle to low cost biological processing, and development of more easily converted plants and more effective enzymes would be of great benefit. Because no single parameter describes recalcitrance, superior variants canonlybeidentifiedbymeasuring sugarreleasefrom plants subjected to pretreatment and enzymatic hydrolysis. How- ever, genetic modifications of plants coupled with molecular engineering of deconstruction proteins and definition of pretreatment conditions create a very large sample set, and previous methods for Biomass pretreatment at elevated temperatures and pressures prevented use of a fully inte- grated high-throughput (HTP) screening pipeline. Herein, we report on the engineering of a novel HTP pretreatment system employing a 96 well-plate format that withstands extreme pretreatment conditions for rapid screening of Biomass-enzyme-pretreatment combinations. This includes the development of new approaches to steam heating and water quenching the system that result in much faster heat up and cool down than previously possible and show consistent temperature histories across the multiwell plate. Coupled pretreatment and enzymatic hydrolysis perfor- mance of the well plate pretreatment system is shown to be consistent among the many wells in the device and also with performance of conventional tubular reactors. Biotechnol. Bioeng. 2010;105: 231-238. 2009 Wiley Periodicals, Inc.
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engineering of a high throughput screening system to identify Cellulosic Biomass pretreatments and enzyme formulations that enhance sugar release
Biotechnology and Bioengineering, 2010Co-Authors: Michael H Studer, Simone Brethauer, Jaclyn D Demartini, Heather L Mckenzie, Charles E. WymanAbstract:The recalcitrance of Cellulosic Biomass, the only abundant, sustainable feedstock for making liquid fuels, is a primary obstacle to low cost biological processing, and development of more easily converted plants and more effective enzymes would be of great benefit. Because no single parameter describes recalcitrance, superior variants can only be identified by measuring sugar release from plants subjected to pretreatment and enzymatic hydrolysis. However, genetic modifications of plants coupled with molecular engineering of deconstruction proteins and definition of pretreatment conditions create a very large sample set, and previous methods for Biomass pretreatment at elevated temperatures and pressures prevented use of a fully integrated high-throughput (HTP) screening pipeline. Herein, we report on the engineering of a novel HTP pretreatment system employing a 96 well-plate format that withstands extreme pretreatment conditions for rapid screening of Biomass-enzyme-pretreatment combinations. This includes the development of new approaches to steam heating and water quenching the system that result in much faster heat up and cool down than previously possible and show consistent temperature histories across the multiwell plate. Coupled pretreatment and enzymatic hydrolysis performance of the well plate pretreatment system is shown to be consistent among the many wells in the device and also with performance of conventional tubular reactors.
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Cellulosic ethanol a unique sustainable liquid transportation fuel
Mrs Bulletin, 2008Co-Authors: Charles E. WymanAbstract:Although ethanol is now made from the sugars in the starch fraction of corn and other crops and from the sugar in sugarcane, a much greater impact for ethanol in terms of fuel use could be realized if the sugars from more recalcitrant Cellulosic Biomass could be converted to ethanol. Cellulosic Biomass is the structural portion of plants and includes agricultural (e.g., corn stover, which is all of the above-ground portion of the corn plant, excluding the grain) and forestry (e.g., sawdust) residues, major fractions of municipal solid waste (e.g., waste paper and yard waste), and herbaceous (e.g., switchgrass) and woody (e.g., poplar) crops grown as energy resources. Although distinctive in outward appearance, these materials all comprise about 40–50% cellulose and 20–30% hemicellulose, with lesser amounts of lignin and other compounds such as sugars, oils, and minerals. Cellulose is a polymer of glucose sugar molecules that are physically linked together in a crystalline structure to provide structural support for plants. Hemicellulose is also made up of sugars covalently joined together in long chains, but it generally includes fve different sugars: arabinose, galactose, glucose, mannose, and xylose. In addition, hemicellulose is an amorphous, branched material. Lignin is a phenylpropene compound that can be viewed as a low-sulfur, immature coal.
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the effect of flow rate of very dilute sulfuric acid on xylan lignin and total mass removal from corn stover
Industrial & Engineering Chemistry Research, 2004Co-Authors: Chaogang Liu, Charles E. WymanAbstract:Flowing compressed hot water through Cellulosic Biomass enhances removal of total mass, xylan, and lignin and increases cellulose digestibility compared to batch operations at otherwise identical c...
Z J Pei - One of the best experts on this subject based on the ideXlab platform.
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AN EXPERIMENTAL STUDY ON TEMPERATURE IN ULTRASONIC VIBRATION-ASSISTED PELLETING OF Cellulosic Biomass
2020Co-Authors: Q Feng, Z J Pei, W L Cong, M Zhang, C Z RenAbstract:ABSTRACT As one of the near-to-mid-term alternatives to fossil fuels, Cellulosic biofuels can cut greenhouse gas emissions while continuing to meet liquid transportation fuel needs. By processing Cellulosic Biomass into pellets, density and handling efficiency of Cellulosic feedstocks will be improved, resulting in a reduction in transportation and handling costs in biofuel manufacturing. Temperature of Biomass during the pelleting process can affect the quality of the pellet. But effects of pelleting variables on Biomass temperature during ultrasonic vibration-assisted (UV-A) pelleting are still unknown. This paper reports an experimental investigation on temperature of Biomass in UV-A pelleting. It studies the effects of moisture content of the Biomass and pelleting variables (ultrasonic power, tool travel distance, and feedrate). The results will be helpful in understanding the effects of ultrasonic vibration on Biomass temperature, compaction mechanism, and biofuel conversion
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ultrasonic vibration assisted pelleting of Cellulosic Biomass for biofuel production
2015Co-Authors: Meng Zhang, Xiaoxu Song, Z J Pei, Donghai WangAbstract:Cellulosic biofuels have the potential to partially replace petroleum-based liquid transportation fuels. Several technical barriers hinder large-scale and cost-effective production of Cellulosic biofuels, such as the low density of Cellulosic Biomass feedstocks (causing high transportation and storage cost), and the lack of efficient pretreatment technologies for Cellulosic Biomass. Ultrasonic vibration-assisted (UV-A) pelleting is a novel Biomass feedstock preprocessing technology. UV-A pelleting is characterized by a combination of pelletizing and ultrasonic treatment into one process. This chapter reports experimental and theoretical investigations on UV-A pelleting of Cellulosic Biomass for biofuel production. It covers studies on pellet quality, pellet sugar yield, pelleting energy consumption, and pelleting temperature.
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ultrasonic vibration assisted pelleting of wheat straw a predictive model for energy consumption using response surface methodology
Ultrasonics, 2014Co-Authors: Xiaoxu Song, Meng Zhang, Z J PeiAbstract:Cellulosic Biomass can be used as a feedstock for biofuel manufacturing. Pelleting of Cellulosic Biomass can increase its bulk density and thus improve its storability and reduce the feedstock transportation costs. Ultrasonic vibration-assisted (UV-A) pelleting can produce Biomass pellets whose density is comparable to that processed by traditional pelleting methods (e.g. extruding, briquetting, and rolling). This study applied response surface methodology to the development of a predictive model for the energy consumption in UV-A pelleting of wheat straw. Effects of pelleting pressure, ultrasonic power, sieve size, and pellet weight were investigated. This study also optimized the process parameters to minimize the energy consumption in UV-A pelleting using response surface methodology. Optimal conditions to minimize the energy consumption were the following: ultrasonic power at 20%, sieve size at 4 mm, and pellet weight at 1g, and the minimum energy consumption was 2.54 Wh.
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Effects of ultrasonic vibration-assisted pelleting of Cellulosic Biomass on sugar yield for biofuel manufacturing
Biomass Conversion and Biorefinery, 2013Co-Authors: Xiaoxu Song, Meng Zhang, Z J PeiAbstract:Ultrasonic vibration-assisted (UV-A) pelleting can increase the bulk density of Cellulosic Biomass, thus reduce the feedstock transportation cost in Cellulosic biofuel manufacturing. UV-A pelleting can also increase the Biomass sugar yield in enzymatic hydrolysis. There are two major processes in the sugar conversion of Cellulosic Biomass: pretreatment and enzymatic hydrolysis. Sugar yield definition used in reported UV-A pelleting studies is enzymatic hydrolysis sugar yield. This definition is based on enzymatic hydrolysis this single process without considering the pretreatment process. In fact, converting Cellulosic Biomass into fermentable sugar (glucose) is the combined effort of pretreatment and enzymatic hydrolysis. There are no papers in the literature investigating whether UV-A pelleting could increase the total sugar yield when both pretreatment and enzymatic hydrolysis are considered. This paper reports the first study using total sugar yield to investigate the effects UV-A pelleting on Biomass sugar yield. Experimental results show that, for all the four types of Cellulosic Biomass (wheat straw, corn stover, switchgrass, and sorghum stalk) used in this study, total sugar yield of Biomass processed with UV-A pelleting was 30 to 43 % higher than that of Biomass not processed with UV-A pelleting.
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ultrasonic vibration assisted pelleting for Cellulosic biofuel manufacturing investigation on power consumption
Renewable Energy, 2013Co-Authors: Qi Zhang, Pengfei Zhang, Z J Pei, Donghai WangAbstract:Abstract Cellulosic ethanol produced from Cellulosic Biomass is an alternative to petroleum-based transportation fuels. Raw Cellulosic Biomass has low density, causing high costs in their storage, transportation, and handling. Ultrasonic vibration-assisted (UV-A) pelleting can increase the density of Cellulosic Biomass. Effects of UV-A pelleting variables on pellet quality (density, durability, stability, and strength) and sugar yield have been reported. However, power consumption in UV-A pelleting has not been fully investigated. This paper presents an experimental investigation on power consumption in UV-A pelleting of wheat straw. Effects of input variables (Biomass moisture content, Biomass particle size, pelleting pressure, and ultrasonic power) on power consumption are investigated. Results show that power consumption in UV-A pelleting increases as moisture content and particle size decrease, and as pelleting pressure and ultrasonic power increase.
Yasushi Morikawa - One of the best experts on this subject based on the ideXlab platform.
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construction of a recombinant trichoderma reesei strain expressing aspergillus aculeatus β glucosidase 1 for efficient Biomass conversion
Biotechnology and Bioengineering, 2012Co-Authors: Hikaru Nakazawa, Junichi Sumitani, Shuji Tani, Takashi Kawaguchi, Tetsushi Kawai, Noriko Ida, Yosuke Shida, Yoshinori Kobayashi, Hirofumi Okada, Yasushi MorikawaAbstract:To develop a Trichoderma reesei strain appropriate for the saccharification of pretreated Cellulosic Biomass, a recombinant T. reesei strain, X3AB1, was constructed that expressed an Aspergillus aculeatus β-glucosidase 1 with high specific activity under the control of the xyn3 promoter. The culture supernatant from T. reesei X3AB1 grown on 1% Avicel as a carbon source had 63- and 25-fold higher β-glucosidase activity against cellobiose compared to that of the parent strain PC-3-7 and that of the T. reesei recombinant strain expressing an endogenous β-glucosidase I, respectively. Further, the xylanase activity was 30% lower than that of PC-3-7 due to the absence of xyn3. X3AB1 grown on 1% Avicel-0.5% xylan medium produced 2.3- and 3.3-fold more xylanase and β-xylosidase, respectively, than X3AB1 grown on 1% Avicel. The supernatant from X3AB1 grown on Avicel and xylan saccharified NaOH-pretreated rice straw efficiently at a low enzyme dose, indicating that the strain has good potential for use in Cellulosic Biomass conversion processes. Biotechnol. Bioeng. 2012;109: 92–99. © 2011 Wiley Periodicals, Inc.
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construction of a recombinant trichoderma reesei strain expressing aspergillus aculeatus β glucosidase 1 for efficient Biomass conversion
Biotechnology and Bioengineering, 2012Co-Authors: Hikaru Nakazawa, Junichi Sumitani, Shuji Tani, Takashi Kawaguchi, Tetsushi Kawai, Noriko Ida, Yosuke Shida, Yoshinori Kobayashi, Hirofumi Okada, Yasushi MorikawaAbstract:To develop a Trichoderma reesei strain appropriate for the saccharification of pretreated Cellulosic Biomass, a recombinant T. reesei strain, X3AB1, was constructed that expressed an Aspergillus aculeatus β-glucosidase 1 with high specific activity under the control of the xyn3 promoter. The culture supernatant from T. reesei X3AB1 grown on 1% Avicel as a carbon source had 63- and 25-fold higher β-glucosidase activity against cellobiose compared to that of the parent strain PC-3-7 and that of the T. reesei recombinant strain expressing an endogenous β-glucosidase I, respectively. Further, the xylanase activity was 30% lower than that of PC-3-7 due to the absence of xyn3. X3AB1 grown on 1% Avicel-0.5% xylan medium produced 2.3- and 3.3-fold more xylanase and β-xylosidase, respectively, than X3AB1 grown on 1% Avicel. The supernatant from X3AB1 grown on Avicel and xylan saccharified NaOH-pretreated rice straw efficiently at a low enzyme dose, indicating that the strain has good potential for use in Cellulosic Biomass conversion processes.
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, David A. Hogsett, Lee R Lynd, Venkatesh BalanAbstract: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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consolidated bioprocessing of Cellulosic Biomass to ethanol using thermophilic bacteria
Bioenergy, 2008Co-Authors: Lee R Lynd, Nicky Ciazza, Chris Herring, Devin Currie, Nick OremAbstract:This chapter considers use of thermophilic bacteria to produce ethanol in a consolidated bioprocessing (CBP) configuration. It mainly focuses on cellulose conversion, as it represents the largest technical challenge for development of CBP-enabling microorganisms, with an emphasis on recent developments pertaining to processing of cellulose by cellulolytic microorganisms. Thermophilic bacteria was first considered for CBP with respect to diversity and ecology, utilization of nonglucose sugars, and ethanol tolerance. Since some pretreatment processes solubilize essentially all of the hemicellulose, it may or may not be necessary that insoluble hemicellulose be enzymatically hydrolyzed in the context of industrial processing of Cellulosic Biomass. The major component of angiosperm hemicellulose is xylan that can be esterified or acylated by phenolic residues such as ferulic acid and p-coumaric acid. Therefore, it is not surprising that hemicellulolytic bacteria must express a large set of cooperating enzymes in order to efficiently and completely hydrolyze hemicellulose and assimilate products of this hydrolysis. The authors concluded that a system similar to catabolite repression may be responsible for the apparent inhibition of cellulase synthesis and proposed that over time as cellobiose was metabolized, its concentration would drop below the point necessary to inhibit cellulase transcription. This work contradicted earlier studies which had concluded that the endoglucanase activity in C. thermocellum was constitutive.
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Consolidated bioprocessing of Cellulosic Biomass: an update
Current Opinion in Biotechnology, 2005Co-Authors: Lee R Lynd, John Mcbride, Mark LaserAbstract:Biologically mediated processes seem promising for energy conversion, in particular for the conversion of lignoCellulosic Biomass into fuels. Although processes featuring a step dedicated to the production of cellulase enzymes have been the focus of most research efforts to date, consolidated bioprocessing (CBP) – featuring cellulase production, cellulose hydrolysis and fermentation in one step – is an alternative approach with outstanding potential. Progress in developing CBP-enabling microorganisms is being made through two strategies: engineering naturally occurring cellulolytic microorganisms to improve product-related properties, such as yield and titer, and engineering non-cellulolytic organisms that exhibit high product yields and titers to express a heterologous cellulase system enabling cellulose utilization. Recent studies of the fundamental principles of microbial cellulose utilization support the feasibility of CBP.
Shuji Tani - One of the best experts on this subject based on the ideXlab platform.
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effects of clbr overexpression on enzyme production in aspergillus aculeatus vary depending on the Cellulosic Biomass degrading enzyme species
Bioscience Biotechnology and Biochemistry, 2015Co-Authors: Emi Kunitake, Junichi Sumitani, Shuji Tani, Ayano Kawamura, Shigeo Takenaka, Wataru Ogasawara, Takashi KawaguchiAbstract:ClbR is a Zn(II)2Cys6 transcriptional activator that controls the expression of cellulase-related genes in response to Avicel and cellobiose in Aspergillus aculeatus. A clbR-overexpressing strain (clbR-OE) that expresses the clbR gene at levels sevenfold higher than the control strain sustainably produced xylanolytic and cellulolytic activities during 10-day cultivation of A. aculeatus, enabling synchronization of xylanolytic and cellulolytic activities at a maximum level. However, clbR overexpression did not simultaneously increase levels of all xylanolytic and cellulolytic enzymes. Peptide mass fingerprint analysis revealed markedly increased production of FIa-xylanase in clbR-OE, whereas expression of FIII-avicelase and FII-carboxymethyl cellulase was unaffected and expression of hydrocellulase was lower in clbR-OE than in the control. Northern blot analysis confirmed that these effects of clbR overexpression on enzyme production were mediated at the transcriptional level. These data suggest that ClbR participates in diverse signaling pathways to control the expression of Cellulosic Biomass-degrading enzymes in A. aculeatus.
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Complex regulation of hydrolytic enzyme genes for Cellulosic Biomass degradation in filamentous fungi
Applied Microbiology and Biotechnology, 2014Co-Authors: Shuji Tani, Takashi Kawaguchi, Tetsuo KobayashiAbstract:Filamentous fungi produce cellulolytic and hemicellulolytic enzymes in response to small inducer molecules liberated from Cellulosic Biomass. Enzyme production is mainly regulated at the level of transcription. The first transcription factor identified as being involved in Cellulosic Biomass degradation was XlnR, which mediates d -xylose-triggered induction of xylanolytic and cellulolytic genes in Aspergillus . XlnR has played the leading role for over a decade in studies aimed at clarification of gene regulation related to Cellulosic Biomass degradation. Very recently, several new transcription factors were identified, namely Clr-1/2 in Neurospora ; ManR, McmA, and ClbR in Aspergillus ; and BglR in Trichoderma , all of which participate in the regulation of cellulolytic and/or hemicellulolytic enzyme production. Furthermore, as well as the carbon sources available, other factors such as light signaling and anti-sense RNA accumulation have been shown to contribute to this regulation. Here, we review the recent advancements demonstrating that multiple factors coordinately regulate the expression of Cellulosic Biomass degrading enzyme genes.
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construction of a recombinant trichoderma reesei strain expressing aspergillus aculeatus β glucosidase 1 for efficient Biomass conversion
Biotechnology and Bioengineering, 2012Co-Authors: Hikaru Nakazawa, Junichi Sumitani, Shuji Tani, Takashi Kawaguchi, Tetsushi Kawai, Noriko Ida, Yosuke Shida, Yoshinori Kobayashi, Hirofumi Okada, Yasushi MorikawaAbstract:To develop a Trichoderma reesei strain appropriate for the saccharification of pretreated Cellulosic Biomass, a recombinant T. reesei strain, X3AB1, was constructed that expressed an Aspergillus aculeatus β-glucosidase 1 with high specific activity under the control of the xyn3 promoter. The culture supernatant from T. reesei X3AB1 grown on 1% Avicel as a carbon source had 63- and 25-fold higher β-glucosidase activity against cellobiose compared to that of the parent strain PC-3-7 and that of the T. reesei recombinant strain expressing an endogenous β-glucosidase I, respectively. Further, the xylanase activity was 30% lower than that of PC-3-7 due to the absence of xyn3. X3AB1 grown on 1% Avicel-0.5% xylan medium produced 2.3- and 3.3-fold more xylanase and β-xylosidase, respectively, than X3AB1 grown on 1% Avicel. The supernatant from X3AB1 grown on Avicel and xylan saccharified NaOH-pretreated rice straw efficiently at a low enzyme dose, indicating that the strain has good potential for use in Cellulosic Biomass conversion processes. Biotechnol. Bioeng. 2012;109: 92–99. © 2011 Wiley Periodicals, Inc.
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construction of a recombinant trichoderma reesei strain expressing aspergillus aculeatus β glucosidase 1 for efficient Biomass conversion
Biotechnology and Bioengineering, 2012Co-Authors: Hikaru Nakazawa, Junichi Sumitani, Shuji Tani, Takashi Kawaguchi, Tetsushi Kawai, Noriko Ida, Yosuke Shida, Yoshinori Kobayashi, Hirofumi Okada, Yasushi MorikawaAbstract:To develop a Trichoderma reesei strain appropriate for the saccharification of pretreated Cellulosic Biomass, a recombinant T. reesei strain, X3AB1, was constructed that expressed an Aspergillus aculeatus β-glucosidase 1 with high specific activity under the control of the xyn3 promoter. The culture supernatant from T. reesei X3AB1 grown on 1% Avicel as a carbon source had 63- and 25-fold higher β-glucosidase activity against cellobiose compared to that of the parent strain PC-3-7 and that of the T. reesei recombinant strain expressing an endogenous β-glucosidase I, respectively. Further, the xylanase activity was 30% lower than that of PC-3-7 due to the absence of xyn3. X3AB1 grown on 1% Avicel-0.5% xylan medium produced 2.3- and 3.3-fold more xylanase and β-xylosidase, respectively, than X3AB1 grown on 1% Avicel. The supernatant from X3AB1 grown on Avicel and xylan saccharified NaOH-pretreated rice straw efficiently at a low enzyme dose, indicating that the strain has good potential for use in Cellulosic Biomass conversion processes.