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Title: Characterization of Rice Straw Prehydrolyzates and Their Effect on the Hydrolysis of Model Substrates Using a Commercial endo -Cellulase, β-Glucosidase and Cellulase Cocktail

 [1];  [2]
  1. Department of Food Science, University of Arkansas, 2650 N. Young Ave, Fayetteville, Arkansas 72704, United States
  2. Department of Biological and Agricultural Engineering, University of Arkansas, 203 Engineering Hall, Fayetteville, Arkansas 72701, United States
Publication Date:
Sponsoring Org.:
OSTI Identifier:
Grant/Contract Number:
Resource Type:
Journal Article: Published Article
Journal Name:
ACS Sustainable Chemistry & Engineering
Additional Journal Information:
Journal Volume: 2; Journal Issue: 9; Related Information: CHORUS Timestamp: 2017-12-01 13:15:43; Journal ID: ISSN 2168-0485
American Chemical Society
Country of Publication:
United States

Citation Formats

Rajan, Kalavathy, and Carrier, Danielle Julie. Characterization of Rice Straw Prehydrolyzates and Their Effect on the Hydrolysis of Model Substrates Using a Commercial endo -Cellulase, β-Glucosidase and Cellulase Cocktail. United States: N. p., 2014. Web. doi:10.1021/sc5002947.
Rajan, Kalavathy, & Carrier, Danielle Julie. Characterization of Rice Straw Prehydrolyzates and Their Effect on the Hydrolysis of Model Substrates Using a Commercial endo -Cellulase, β-Glucosidase and Cellulase Cocktail. United States. doi:10.1021/sc5002947.
Rajan, Kalavathy, and Carrier, Danielle Julie. Thu . "Characterization of Rice Straw Prehydrolyzates and Their Effect on the Hydrolysis of Model Substrates Using a Commercial endo -Cellulase, β-Glucosidase and Cellulase Cocktail". United States. doi:10.1021/sc5002947.
title = {Characterization of Rice Straw Prehydrolyzates and Their Effect on the Hydrolysis of Model Substrates Using a Commercial endo -Cellulase, β-Glucosidase and Cellulase Cocktail},
author = {Rajan, Kalavathy and Carrier, Danielle Julie},
abstractNote = {},
doi = {10.1021/sc5002947},
journal = {ACS Sustainable Chemistry & Engineering},
number = 9,
volume = 2,
place = {United States},
year = {Thu Jul 24 00:00:00 EDT 2014},
month = {Thu Jul 24 00:00:00 EDT 2014}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1021/sc5002947

Citation Metrics:
Cited by: 7works
Citation information provided by
Web of Science

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  • Large-scale production of effective cellulose hydrolytic enzymes is the key to the bioconversion of agricultural residues to ethanol. The goal of this study was to develop a rice plant as a bioreactor for the large-scale production of cellulose hydrolytic enzymes via genetic transformation, and to simultaneously improve rice straw as an efficient biomass feedstock for conversion of cellulose to glucose. In this study, the cellulose hydrolytic enzyme {beta}-1, 4-endoglucanase (E1) from the thermophilic bacterium Acidothermus cellulolyticus was overexpressed in rice through Agrobacterium-mediated transformation. The expression of the bacterial gene in rice was driven by the constitutive Mac promoter, a hybridmore » promoter of Ti plasmid mannopine synthetase promoter and cauliflower mosaic virus 35S promoter enhancer with the signal peptide of tobacco pathogenesis-related protein for targeting the protein to the apoplastic compartment for storage. A total of 52 transgenic rice plants from six independent lines expressing the bacterial enzyme were obtained, which expressed the gene at high levels with a normal phenotype. The specific activities of E1 in the leaves of the highest expressing transgenic rice lines were about 20 fold higher than those of various transgenic plants obtained in previous studies and the protein amounts accounted for up to 6.1% of the total leaf soluble protein. Zymogram and temperature-dependent activity analyses demonstrated the thermostability of the enzyme and its substrate specificity against cellulose, and a simple heat treatment can be used to purify the protein. In addition, hydrolysis of transgenic rice straw with cultured cow gastric fluid yielded almost twice more reducing sugars than wild type straw. Taken together, these data suggest that transgenic rice can effectively serve as a bioreactor for large-scale production of active, thermostable cellulose hydrolytic enzymes. As a feedstock, direct expression of large amount of cellulases in transgenic rice may also facilitate saccharification of cellulose in rice straw and significantly reduce the costs for hydrolytic enzymes.« less
  • Assessment was made to evaluate the effect of hydrogen peroxide pretreatment on the change of the structural features and the enzymatic hydrolysis of rice straw. Changes in the lignin content, weight loss, accessibility for Cadoxen, water holding capacity, and crystallinity of straw were measured during pretreatment to express the modification of the lignocellulosic structure of straw. The rates and the extents of enzymatic hydrolysis, cellulase adsorption, and cellobiose accumulation in the initial stage of hydrolysis were determined to study the pretreatment effect on hydrolysis. Pretreatment at 60 degrees C for 5 hours in a solution with 1% (w/w) H/sub 2/O/submore » 2/ and NaOH resulted in 60% delignification, 40% weight loss, a fivefold increase in the accessibility for Cadoxen, an one times increase in the water-holding capacity, and only a slight decrease in crystallinity as compared with that of the untreated straw. Improvement on the pretreatment effect could be made by increasing the initial alkalinity and the pretreatment temperature of hydrogen peroxide solution. A saturated improvement on the structural features was found when the weight ratio of hydrogen peroxide to straw was above 0.25 g H/sub 2/O/sub 2//g straw in an alkaline H/sub 2/O/sub 2/ solution with 1% (w/w) NaOH at 32 degrees C. The initial rates and extents of hydrolysis, cellulase adsorption, and cellobiose accumulation in hydrolysis were enhanced in acordance with the improved structural features of straw pretreated. A four times increase in the extent of the enzymatic hydrolysis of straw for 24 hours was attributed to the alkaline hydrogen peroxide pretreatment. 29 references.« less
  • Rice BGlu1 β-glucosidase was purified from recombinant E. coli and crystallized with and without the inhibitor 2-deoxy-2-fluoro-β-d-glucose. The crystals diffracted to 2.15 and 2.75 Å, respectively. Rice (Oryza sativa) BGlu1 β-glucosidase was expressed in Escherichia coli with N-terminal thioredoxin and hexahistidine tags and purified by immobilized metal-affinity chromatography (IMAC). After removal of the N-terminal tags, cation-exchange and S-200 gel-filtration chromatography yielded a 50 kDa BGlu1 with >95% purity. The free enzyme and a complex with 2,4-dinitrophenyl-2-deoxy-2-fluoro-β-d-glucopyranoside inhibitor were crystallized by microbatch and hanging-drop vapour diffusion. Small tetragonal crystals of BGlu1 with and without inhibitor grew in 18%(w/v) PEG 8000 withmore » 0.1 M sodium cacodylate pH 6.5 and 0.2 M zinc acetate. Crystals of BGlu1 with inhibitor were streak-seeded into 23%(w/v) PEG MME 5000, 0.2 M ammonium sulfate, 0.1 M MES pH 6.7 to yield larger crystals. Crystals with and without inhibitor diffracted to 2.15 and 2.75 Å resolution, respectively, and had isomorphous orthorhombic unit cells belonging to space group P2{sub 1}2{sub 1}2{sub 1}.« less
  • In this paper, the Production of cellulases and Hemicellulases was studied with Trichoderma reesei Rut C-30, This organism produced, together with high cellulase activities, considerable amounts of xylanases and β-glucosidase. Three cellulose concentration (1, 2.5, and 5.0%) were examined to determined the maximum levels of cellulase activity obtainable in submerged culture. Temperature and pH profiling was used to increase cell mass to maximum levels within two days and thereby enhancing fermentor productivity at higher substrate levels. Finally, the effect of temperature, pH, Tween-80 concentration, carbon sources, and substrate concentration on the ration of mycelial growth and extracellulose enzyme production aremore » described.« less
  • Three commercial cellulase preparations, Novozymes Cellic® Ctec2, Dupont Accellerase® 1500, and DSM Cytolase CL, were evaluated for their hydrolytic activity using a set of reference biomass substrates with controlled substrate characteristics. It was found that lignin remains a significant recalcitrance factor to all the preparations, although different enzyme preparations respond to the inhibitory effect of lignin differently. Also, different types of biomass lignin can inhibit cellulose enzymes in different manners. Enhancing enzyme activity toward biomass fiber swelling is an area significantly contributing to potential improvement in cellulose performance. While the degree of polymerization of cellulose in the reference substrates didmore » not present a major recalcitrance factor to Novozymes Cellic® Ctec2, cellulose crystallite has been shown to have a significant lower reactivity toward all enzyme mixtures. The presence of polysaccharide monooxygenases (PMOs) in Novozymes Ctec2 appears to enhance enzyme activity toward decrystallization of cellulose. This study demonstrated that reference substrates with controlled chemical and physical characteristics of structural features can be applied as an effective and practical strategy to identify cellulosic enzyme activities toward specific biomass recalcitrance factor(s) and provide specific targets for enzyme improvement.« less