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Zhang H, Fan Z, Li J, Han L. A comparative study on enzyme adsorption and hydrolytic performance of different scale corn stover by two-step kinetics. BIORESOURCE TECHNOLOGY 2019; 282:384-389. [PMID: 30884458 DOI: 10.1016/j.biortech.2019.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 06/09/2023]
Abstract
To investigate the effect of two-step kinetics on enzyme adsorption and hydrolytic properties of different structural substrates at low enzyme doses. The two-step kinetic experiments of ultrafine grinding (UGCS) and sieve-based grinding corn stover (SGCS) were performed respectively with enzyme loading of 2.5 + 2.5 FPU/g and 5 + 5 FPU/g. The different performance of these two samples were illustrated by characterizing the particle size distribution, SEM and XPS. The results showed that ultrafine grinding can promote the structural properties which is beneficial to adsorption and hydrolysis. The main factors influencing adsorption kinetics are enzyme concentration and the surface cellulose amount. Pre-adsorbed enzyme has no effects on the subsequent enzyme adsorption quantity but produces some small competitive and impeditive effects. The hydrolysis kinetics mainly depend on the structure of the substrate and its complexity of hydrolysis. The two-step hydrolysis didn't promote the total sugar yield under the same enzyme concentration, but the first step contributed more to the total sugar yield.
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Affiliation(s)
- Haiyan Zhang
- College of Engineering, China Agricultural University (East Campus), 17 Qing-Hua-Dong-Lu, Hai-Dian District, Beijing 100083, PR China
| | - Zhiliang Fan
- Department of Biological and Agricultural Engineering, University of California, Davis, CA 95616, United States
| | - Junbao Li
- College of Engineering, China Agricultural University (East Campus), 17 Qing-Hua-Dong-Lu, Hai-Dian District, Beijing 100083, PR China
| | - Lujia Han
- College of Engineering, China Agricultural University (East Campus), 17 Qing-Hua-Dong-Lu, Hai-Dian District, Beijing 100083, PR China.
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2
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Enhancement and modeling of enzymatic hydrolysis on cellulose from agave bagasse hydrothermally pretreated in a horizontal bioreactor. Carbohydr Polym 2019; 211:349-359. [DOI: 10.1016/j.carbpol.2019.01.111] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/29/2019] [Accepted: 01/31/2019] [Indexed: 11/21/2022]
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3
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Ibrahim E, Jones KD, Taylor KE, Hosseney EN, Mills PL, Escudero JM. Molecular and biochemical characterization of recombinant cel12B, cel8C, and peh28 overexpressed in Escherichia coli and their potential in biofuel production. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:52. [PMID: 28413443 PMCID: PMC5327597 DOI: 10.1186/s13068-017-0732-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 02/11/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND The high crystallinity of cellulosic biomass myofibrils as well as the complexity of their intermolecular structure is a significant impediment for biofuel production. Cloning of celB-, celC-encoded cellulases (cel12B and cel8C) and peh-encoded polygalacturonase (peh28) from Pectobacterium carotovorum subsp. carotovorum (Pcc) was carried out in our previous study using Escherichia coli as a host vector. The current study partially characterizes the enzymes' molecular structures as well as their catalytic performance on different substrates which can be used to improve their potential for lignocellulosic biomass conversion. RESULTS β-Jelly roll topology, (α/α)6 antiparallel helices and right-handed β-helices were the folds identified for cel12B, cel8C, and peh28, respectively, in their corresponding protein model structures. Purifications of 17.4-, 6.2-, and 6.0-fold, compared to crude extract, were achieved for cel12B and cel8C, and peh28, respectively, using specific membrane ultrafiltrations and size-exclusion chromatography. Avicel and carboxymethyl cellulose (CMC) were substrates for cel12B, whereas for cel8C catalytic activity was only shown on CMC. The enzymes displayed significant synergy on CMC but not on Avicel when tested for 3 h at 45 °C. No observed β-glucosidase activities were identified for cel8C and cel12B when tested on p-nitrophenyl-β-d-glucopyranoside. Activity stimulation of 130% was observed when a recombinant β-glucosidase from Pcc was added to cel8C and cel12B as tested for 3 h at 45 °C. Optimum temperature and pH of 45 °C and 5.4, respectively, were identified for all three enzymes using various substrates. Catalytic efficiencies (kcat/Km) were calculated for cel12B and cel8C on CMC as 0.141 and 2.45 ml/mg/s respectively, at 45 °C and pH 5.0 and for peh28 on polygalacturonic acid as 4.87 ml/mg/s, at 40 °C and pH 5.0. Glucose and cellobiose were the end-products identified for cel8C, cel12B, and β-glucosidase acting together on Avicel or CMC, while galacturonic acid and other minor co-products were identified for peh28 action on pectin. CONCLUSIONS This study provides some insight into which parameters should be optimized when application of cel8C, cel12B, and peh28 to biomass conversion is the goal.
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Affiliation(s)
- Eman Ibrahim
- Department of Environmental Engineering, Texas A&M University-Kingsville, Kingsville, TX 78363 USA
- Department of Botany and Microbiology, Al-Azhar University, Nasr City, Cairo, 11884 Egypt
| | - Kim D. Jones
- Department of Environmental Engineering, Texas A&M University-Kingsville, Kingsville, TX 78363 USA
| | - Keith E. Taylor
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4 Canada
| | - Ebtesam N. Hosseney
- Department of Botany and Microbiology, Al-Azhar University, Nasr City, Cairo, 11884 Egypt
| | - Patrick L. Mills
- Department of Chemical Engineering, Texas A&M University-Kingsville, Kingsville, TX 78363 USA
| | - Jean M. Escudero
- Department of Basic Science, St. Louis College of Pharmacy, St. Louis, MO 63110-1088 USA
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Leskinen T, Salas C, Kelley SS, Argyropoulos DS. Wood Extractives Promote Cellulase Activity on Cellulosic Substrates. Biomacromolecules 2015; 16:3226-34. [DOI: 10.1021/acs.biomac.5b00889] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Timo Leskinen
- Departments of Chemistry & Forest Biomaterials, North Carolina State University, Raleigh, North Carolina 27695-8005, United States
| | - Carlos Salas
- Departments of Chemistry & Forest Biomaterials, North Carolina State University, Raleigh, North Carolina 27695-8005, United States
| | - Stephen S. Kelley
- Departments of Chemistry & Forest Biomaterials, North Carolina State University, Raleigh, North Carolina 27695-8005, United States
| | - Dimitris S. Argyropoulos
- Departments of Chemistry & Forest Biomaterials, North Carolina State University, Raleigh, North Carolina 27695-8005, United States
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Pellegrini VOA, Lei N, Kyasaram M, Olsen JP, Badino SF, Windahl MS, Colussi F, Cruys-Bagger N, Borch K, Westh P. Reversibility of substrate adsorption for the cellulases Cel7A, Cel6A, and Cel7B from Hypocrea jecorina. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:12602-12609. [PMID: 25322452 DOI: 10.1021/la5024423] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Adsorption of cellulases on the cellulose surface is an integral part of the catalytic mechanism, and a detailed description of the adsorption process is therefore required for a fundamental understanding of this industrially important class of enzymes. However, the mode of adsorption has proven intricate, and several key questions remain open. Perhaps most notably it is not clear whether the adsorbed enzyme is in dynamic equilibrium with the free population or irreversibly associated with no or slow dissociation. To address this, we have systematically investigated adsorption reversibility for two cellobiohydrolases (Cel7A and Cel6A) and one endoglucanase (Cel7B) on four types of pure cellulose substrates. Specifically, we monitored dilution-induced release of adsorbed enzyme in samples that had previously been brought to a steady state (constant concentration of free enzyme). In simple dilution experiments (without centrifugation), the results consistently showed full reversibility. In contrast to this, resuspension of enzyme-substrate pellets separated by centrifugation showed extensive irreversibility. We conclude that these enzymes are in a dynamic equilibrium between free and adsorbed states but suggest that changes in the physical properties of cellulose caused by compaction of the pellet hampers subsequent release of adsorbed enzyme. This latter effect may be pertinent to both previous controversies in the literature on adsorption reversibility and the development of enzyme recycling protocols in the biomass industry.
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Affiliation(s)
- Vanessa O A Pellegrini
- Research Unit for Functional Biomaterials, NSM, Roskilde University , 1 Universitetsvej, Build. 18.1, DK-4000 Roskilde, Denmark
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Carbohydrate-binding modules of fungal cellulases: occurrence in nature, function, and relevance in industrial biomass conversion. ADVANCES IN APPLIED MICROBIOLOGY 2014; 88:103-65. [PMID: 24767427 DOI: 10.1016/b978-0-12-800260-5.00004-8] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this review, the present knowledge on the occurrence of cellulases, with a special emphasis on the presence of carbohydrate-binding modules (CBMs) in various fungal strains, has been summarized. The importance of efficient fungal cellulases is growing due to their potential uses in biorefinery processes where lignocellulosic biomasses are converted to platform sugars and further to biofuels and chemicals. Most secreted cellulases studied in detail have a bimodular structure containing an active core domain attached to a CBM. CBMs are traditionally been considered as essential parts in cellulases, especially in cellobiohydrolases. However, presently available genome data indicate that many cellulases lack the binding domains in cellulose-degrading organisms. Recent data also demonstrate that CBMs are not necessary for the action of cellulases and they solely increase the concentration of enzymes on the substrate surfaces. On the other hand, in practical industrial processes where high substrate concentrations with low amounts of water are employed, the enzymes have been shown to act equally efficiently with and without CBM. Furthermore, available kinetic data show that enzymes without CBMs can desorb more readily from the often lignaceous substrates, that is, they are not stuck on the substrates and are thus available for new actions. In this review, the available data on the natural habitats of different wood-degrading organisms (with emphasis on the amount of water present during wood degradation) and occurrence of cellulose-binding domains in their genome have been assessed in order to identify evolutionary advantages for the development of CBM-less cellulases in nature.
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Alasepp K, Borch K, Cruys-Bagger N, Badino S, Jensen K, Sørensen TH, Windahl MS, Westh P. In situ stability of substrate-associated cellulases studied by DSC. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7134-7142. [PMID: 24856176 DOI: 10.1021/la500161e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This work shows that differential scanning calorimetry (DSC) can be used to monitor the stability of substrate-adsorbed cellulases during long-term hydrolysis of insoluble cellulose. Thermal transitions of adsorbed enzyme were measured regularly in subsets of a progressing hydrolysis, and the size of the transition peak was used as a gauge of the population of native enzyme. Analogous measurements were made for enzymes in pure buffer. Investigations of two cellobiohydrolases, Cel6A and Cel7A, from Trichoderma reesei, which is an anamorph of the fungus Hypocrea jerorina, showed that these enzymes were essentially stable at 25 °C. Thus, over a 53 h experiment, Cel6A lost less than 15% of the native population and Cel7A showed no detectable loss for either the free or substrate-adsorbed state. At higher temperatures we found significant losses in the native populations, and at the highest tested temperature (49 °C) about 80% Cel6A and 35% of Cel7A was lost after 53 h of hydrolysis. The data consistently showed that Cel7A was more long-term stable than Cel6A and that substrate-associated enzyme was less long-term stable than enzyme in pure buffer stored under otherwise equal conditions. There was no correlation between the intrinsic stability, specified by the transition temperature in the DSC, and the long-term stability derived from the peak area. The results are discussed with respect to the role of enzyme denaturation for the ubiquitous slowdown observed in the enzymatic hydrolysis of cellulose.
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Affiliation(s)
- Kadri Alasepp
- Research Unit for Functional Biomaterials, NSM, Roskilde University. 1 Universitetsvej , Build. 18.1, DK-4000 Roskilde Denmark
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Ciolacu D, Chiriac AI, Pastor FIJ, Kokol V. The influence of supramolecular structure of cellulose allomorphs on the interactions with cellulose-binding domain, CBD3b from Paenibacillus barcinonensis. BIORESOURCE TECHNOLOGY 2014; 157:14-21. [PMID: 24525243 DOI: 10.1016/j.biortech.2014.01.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 01/06/2014] [Accepted: 01/08/2014] [Indexed: 06/03/2023]
Abstract
The interaction of recombinant cellulose-binding domains (CBDs) of endoglucanase Cel9B from Paenibacillus barcinonensis with different cotton cellulose allomorphs (I, II and III) has been investigated, in order to bring new insights regarding the CBD adsorption and desorption processes. The highest CBD adsorption capacity was recorded for cellulose I, confirming the affinity of proteins to the most crystalline substrate. The weakening and splitting of the hydrogen bonds within cellulose structure after CBD adsorption, as well as a decrease of the crystallinity degree were identified by ATR-FTIR spectroscopy and XRD. The CBD's adsorption kinetic was shown to be rendered by properties as, specific surface area and porosity, being confirmed by dynamic vapor sorption measurements. An important influence of temperature (25, 37 and 50°C) and/or pH medium (4, 5.5, 7 and 10) on the CBD desorption capacity was confirmed, being related to the hydrophobic interactions formed between the CBD and the cellulose allomorphs.
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Affiliation(s)
- Diana Ciolacu
- "Petru Poni" Institute of Macromolecular Chemistry, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania
| | - Alina Iulia Chiriac
- Department of Microbiology, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
| | - F I Javier Pastor
- Department of Microbiology, Faculty of Biology, University of Barcelona, Av. Diagonal 643, 08028 Barcelona, Spain
| | - Vanja Kokol
- University of Maribor, Institute of Engineering Materials and Design, Smetanova ulica 17, 2000 Maribor, Slovenia.
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10
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Lin L, Yan R, Jiang W, Shen F, Zhang X, Zhang Y, Deng S, Li Z. Enhanced enzymatic hydrolysis of palm pressed fiber based on the three main components: cellulose, hemicellulose, and lignin. Appl Biochem Biotechnol 2014; 173:409-20. [PMID: 24652599 DOI: 10.1007/s12010-014-0848-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 03/03/2014] [Indexed: 11/26/2022]
Abstract
The enzymatic hydrolysis of the native and the pretreated palm pressed fiber (PPF) was deeply investigated by using the enzyme cocktail ACCELLERASE 1500. Together with the spent PPF from the first hydrolysis and the further doubly-treated PPF, the proportions of three main components were determined and analyzed based on a triangle figure. The proportion (cellulose/hemicelluloses/lignin) in the spent PPF was equal to 44:23:33 and the surface morphology of the spent PPF looks very similar to the native PPF surface showing poor hydrolysis efficiency. After further double treatment, the proportion was changed evidently from the original 44:23:33 to 54:21:25 and the surface structure was significantly disrupted showing a potential to be hydrolyzed completely. Additionally, all samples were characterized by Fourier transform infrared spectroscopy and X-ray diffractogram through considerations of alkaline solution treatment, so as to understand better the nature of biomass hydrolysis, from the aspect of three biomass components.
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Affiliation(s)
- Lili Lin
- Department of Environmental Science and Engineering, College of Resource and Environment, Sichuan Agricultural University, Chengdu, 610065, People's Republic of China,
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11
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Reyes-Ortiz V, Heins RA, Cheng G, Kim EY, Vernon BC, Elandt RB, Adams PD, Sale KL, Hadi MZ, Simmons BA, Kent MS, Tullman-Ercek D. Addition of a carbohydrate-binding module enhances cellulase penetration into cellulose substrates. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:93. [PMID: 23819686 PMCID: PMC3716932 DOI: 10.1186/1754-6834-6-93] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 06/18/2013] [Indexed: 05/03/2023]
Abstract
INTRODUCTION Cellulases are of great interest for application in biomass degradation, yet the molecular details of the mode of action of glycoside hydrolases during degradation of insoluble cellulose remain elusive. To further improve these enzymes for application at industrial conditions, it is critical to gain a better understanding of not only the details of the degradation process, but also the function of accessory modules. METHOD We fused a carbohydrate-binding module (CBM) from family 2a to two thermophilic endoglucanases. We then applied neutron reflectometry to determine the mechanism of the resulting enhancements. RESULTS Catalytic activity of the chimeric enzymes was enhanced up to three fold on insoluble cellulose substrates as compared to wild type. Importantly, we demonstrate that the wild type enzymes affect primarily the surface properties of an amorphous cellulose film, while the chimeras containing a CBM alter the bulk properties of the amorphous film. CONCLUSION Our findings suggest that the CBM improves the efficiency of these cellulases by enabling digestion within the bulk of the film.
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Affiliation(s)
- Vimalier Reyes-Ortiz
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Department of Bioengineering, University of California, Berkeley, CA 94720, US
| | - Richard A Heins
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Sandia National Laboratories, Livermore, CA 94550, US
| | - Gang Cheng
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Sandia National Laboratories, Livermore, CA 94550, US
| | - Edward Y Kim
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, US
| | - Briana C Vernon
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Sandia National Laboratories, Albuquerque, NM 87185, US
| | - Ryan B Elandt
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
| | - Paul D Adams
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Department of Bioengineering, University of California, Berkeley, CA 94720, US
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, US
| | - Kenneth L Sale
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Sandia National Laboratories, Livermore, CA 94550, US
| | - Masood Z Hadi
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Sandia National Laboratories, Livermore, CA 94550, US
| | - Blake A Simmons
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Sandia National Laboratories, Livermore, CA 94550, US
| | - Michael S Kent
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Sandia National Laboratories, Albuquerque, NM 87185, US
| | - Danielle Tullman-Ercek
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, CA 94608, US
- Department of Bioengineering, University of California, Berkeley, CA 94720, US
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720, US
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, US
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12
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A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion. APPLIED SCIENCES-BASEL 2013. [DOI: 10.3390/app3020396] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Elliston A, Collins SR, Wilson DR, Roberts IN, Waldron KW. High concentrations of cellulosic ethanol achieved by fed batch semi simultaneous saccharification and fermentation of waste-paper. BIORESOURCE TECHNOLOGY 2013; 134:117-26. [PMID: 23500568 PMCID: PMC3629557 DOI: 10.1016/j.biortech.2013.01.084] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 01/14/2013] [Accepted: 01/16/2013] [Indexed: 05/24/2023]
Abstract
A fundamental goal of second generation ethanol production is to increase the ethanol concentration to 10% (v/v) or more to optimise distillation costs. Semi simultaneous saccharification and fermentations (SSSF) were conducted at small pilot scale (5L) utilising fed-batch additions of solid shredded copier paper substrate. Early addition of Accellerase® 1500 at 16 FPU/g substrate and 30 U/g β-glucosidase followed by substrate only batch addition allowed low final equivalent enzyme concentrations to be achieved (3.7 FPU/g substrate) whilst maintaining digestion. Batch addition resulted in a cumulative substrate concentration equivalent to 65% (w/v). This in turn resulted in the production of high concentrations of ethanol (11.6% v/v). The success of this strategy relied on the capacity of the bioreactor to perform high shear mixing as required. Further research into the timing and number of substrate additions could lead to further improvement in overall yields from the 65.5% attained.
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Affiliation(s)
| | | | | | | | - Keith W. Waldron
- Corresponding author. Tel.: +44 (0)1603 255385; fax: +44 (0)1603 507723.
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Martín-Sampedro R, Rahikainen JL, Johansson LS, Marjamaa K, Laine J, Kruus K, Rojas OJ. Preferential Adsorption and Activity of Monocomponent Cellulases on Lignocellulose Thin Films with Varying Lignin Content. Biomacromolecules 2013; 14:1231-9. [DOI: 10.1021/bm400230s] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Raquel Martín-Sampedro
- Department of Forest Products
Technology, School of Chemical Technology, Aalto University, FI-00076 Aalto, Espoo, Finland
| | - Jenni L. Rahikainen
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo,
Finland
| | - Leena-Sisko Johansson
- Department of Forest Products
Technology, School of Chemical Technology, Aalto University, FI-00076 Aalto, Espoo, Finland
| | - Kaisa Marjamaa
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo,
Finland
| | - Janne Laine
- Department of Forest Products
Technology, School of Chemical Technology, Aalto University, FI-00076 Aalto, Espoo, Finland
| | - Kristiina Kruus
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo,
Finland
| | - Orlando J. Rojas
- Department of Forest Products
Technology, School of Chemical Technology, Aalto University, FI-00076 Aalto, Espoo, Finland
- Departments of Forest
and Biomaterials
and Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United
States
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Murphy L, Bohlin C, Baumann MJ, Olsen SN, Sørensen TH, Anderson L, Borch K, Westh P. Product inhibition of five Hypocrea jecorina cellulases. Enzyme Microb Technol 2013; 52:163-9. [DOI: 10.1016/j.enzmictec.2013.01.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 01/02/2013] [Accepted: 01/03/2013] [Indexed: 10/27/2022]
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16
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Chauve M, Barre L, Tapin-Lingua S, Silva Perez DD, Decottignies D, Perez S, Ferreira NL. Evolution and impact of cellulose architecture during enzymatic hydrolysis by fungal cellulases. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/abb.2013.412146] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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17
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Matano Y, Hasunuma T, Kondo A. Simultaneous improvement of saccharification and ethanol production from crystalline cellulose by alleviation of irreversible adsorption of cellulase with a cell surface-engineered yeast strain. Appl Microbiol Biotechnol 2012. [DOI: 10.1007/s00253-012-4587-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Maurer SA, Bedbrook CN, Radke CJ. Competitive sorption kinetics of inhibited endo- and exoglucanases on a model cellulose substrate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:14598-608. [PMID: 22966968 DOI: 10.1021/la3024524] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
For the first time, the competitive adsorption of inhibited cellobiohydrolase I (Cel7A, an exoglucanase) and endoglucanase I (Cel7B) from T. longibrachiatum is studied on cellulose. Using quartz crystal microgravimetry (QCM), sorption histories are measured for individual types of cellulases and their mixtures adsorbing to and desorbing from a model cellulose surface. We find that Cel7A has a higher adsorptive affinity for cellulose than does Cel7B. The adsorption of both cellulases becomes irreversible on time scales of 30-60 min, which are much shorter than those typically used for industrial cellulose hydrolysis. A multicomponent Langmuir kinetic model including first-order irreversible binding is proposed. Although adsorption and desorption rate constants differ between the two enzymes, the rate at which each surface enzyme irreversibly binds is identical. Because of the higher affinity of Cel7A for the cellulose surface, when Cel7A and Cel7B compete for surface sites, a significantly higher bulk concentration of Cel7B is required to achieve comparable surface enzyme concentrations. Because cellulose deconstruction benefits significantly from the cooperative activity of endoglucanases and cellobiohydrolases on the cellulose surface, accounting for competitive adsorption is crucial to developing effective cellulase mixtures.
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Affiliation(s)
- Samuel A Maurer
- Department of Chemical and Biomolecular Engineering, University of California-Berkeley, Berkeley, California 94720-1462, USA
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Maurer SA, Bedbrook CN, Radke CJ. Cellulase Adsorption and Reactivity on a Cellulose Surface from Flow Ellipsometry. Ind Eng Chem Res 2012. [DOI: 10.1021/ie3008538] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S. A. Maurer
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720-1462, United States
| | - C. N. Bedbrook
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720-1462, United States
| | - C. J. Radke
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720-1462, United States
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20
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Liu HQ, Feng Y, Zhao DQ, Jiang JX. Influence of cellulose content on the enzyme activity in the saccharification digests of furfural residues. ASIA-PAC J CHEM ENG 2012. [DOI: 10.1002/apj.1644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- H. Q. Liu
- Department of Chemistry and Chemical Engineering; Beijing Forestry University; Beijing; 100083; China
| | - Y. Feng
- Department of Chemistry and Chemical Engineering; Beijing Forestry University; Beijing; 100083; China
| | - D. Q. Zhao
- Department of Chemistry and Chemical Engineering; Beijing Forestry University; Beijing; 100083; China
| | - J. X. Jiang
- Department of Chemistry and Chemical Engineering; Beijing Forestry University; Beijing; 100083; China
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21
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Eckard AD, Muthukumarappan K, Gibbons W. Modeling of Pretreatment Condition of Extrusion-Pretreated Prairie Cordgrass and Corn Stover with Poly (Oxyethylen)20 Sorbitan Monolaurate. Appl Biochem Biotechnol 2012; 167:377-93. [DOI: 10.1007/s12010-012-9698-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 04/16/2012] [Indexed: 11/29/2022]
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22
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Cruys-Bagger N, Elmerdahl J, Praestgaard E, Tatsumi H, Spodsberg N, Borch K, Westh P. Pre-steady-state kinetics for hydrolysis of insoluble cellulose by cellobiohydrolase Cel7A. J Biol Chem 2012; 287:18451-8. [PMID: 22493488 DOI: 10.1074/jbc.m111.334946] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transient kinetic behavior of enzyme reactions prior to the establishment of steady state is a major source of mechanistic information, yet this approach has not been utilized for cellulases acting on their natural substrate, insoluble cellulose. Here, we elucidate the pre-steady-state regime for the exo-acting cellulase Cel7A using amperometric biosensors and an explicit model for processive hydrolysis of cellulose. This analysis allows the identification of a pseudo-steady-state period and quantification of a processivity number as well as rate constants for the formation of a threaded enzyme complex, processive hydrolysis, and dissociation, respectively. These kinetic parameters elucidate limiting factors in the cellulolytic process. We concluded, for example, that Cel7A cleaves about four glycosidic bonds/s during processive hydrolysis. However, the results suggest that stalling the processive movement and low off-rates result in a specific activity at pseudo-steady state that is 10-25-fold lower. It follows that the dissociation of the enzyme-substrate complex (half-time of ~30 s) is rate-limiting for the investigated system. We suggest that this approach can be useful in attempts to unveil fundamental reasons for the distinctive variability in hydrolytic activity found in different cellulase-substrate systems.
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Affiliation(s)
- Nicolaj Cruys-Bagger
- Department of Science, Systems, and Models, Roskilde University, Roskilde, Denmark
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23
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Rodrigues AC, Leitão AF, Moreira S, Felby C, Gama M. Recycling of cellulases in lignocellulosic hydrolysates using alkaline elution. BIORESOURCE TECHNOLOGY 2012; 110:526-33. [PMID: 22357293 DOI: 10.1016/j.biortech.2012.01.140] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 01/20/2012] [Accepted: 01/24/2012] [Indexed: 05/18/2023]
Abstract
The recovery of cellulases from lignin, lignocellulosic hydrolysates and cellulose by alkaline washes at pH 9 and 10 was examined. The effect of the pH on the structural stability of purified Cel7A was analyzed by circular dichroism. Purified Cel7A showed conformational changes at pH 9 and 10 that were reversible at pH 4.8. Temperature influenced the enzymatic hydrolysis of wheat straw and may be critical for the efficiency of cellulase recycling from wheat straw hydrolysates. Operation at moderate temperatures (37°C) resulted in a rate of saccharification 19% higher than that obtained at 50° C, improving cellulase recycling by 49%. Over 60% of the enzyme activity on the synthetic substrate 4-methylumbelliferyl-β-d-cellobioside (MUC) may be recovered by using a simple alkaline wash. This is thus a promising strategy for enzyme recycling that is simple to implement at industrial scale, economical and effective.
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Affiliation(s)
- Ana Cristina Rodrigues
- Departamento Engenharia Biológica, Universidade do Minho, Campus de Gualtar 4710-057 Braga, Portugal
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24
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Cellulolytic Enzyme Production and Enzymatic Hydrolysis for Second-Generation Bioethanol Production. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2012; 128:1-24. [DOI: 10.1007/10_2011_131] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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25
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Abstract
Natural cellulolytic enzyme systems as well as leading commercial cellulase cocktails are dominated by enzymes that degrade cellulose chains in a processive manner. Despite the abundance of processivity among natural cellulases, the molecular basis as well as the biotechnological implications of this mechanism are only partly understood. One of the major limitations lies in the fact that it is not straightforward to measure and quantify processivity in what essentially are biphasic experimental systems. Here, we describe and discuss both well-established methods and newer methods for measuring cellulase processivity. In addition, we discuss recent insights from studies on chitinases that may help direct further studies on processivity in cellulases.
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Affiliation(s)
- Svein J Horn
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway
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26
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Yu Z, Jameel H, Chang HM, Philips R, Park S. Evaluation of the factors affecting avicel reactivity using multi-stage enzymatic hydrolysis. Biotechnol Bioeng 2011; 109:1131-9. [DOI: 10.1002/bit.24386] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 11/05/2011] [Accepted: 11/14/2011] [Indexed: 11/10/2022]
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27
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Evaluating kinetics of enzymatic saccharification of lignocellulose by fractal kinetic analysis. BIOTECHNOL BIOPROC E 2011. [DOI: 10.1007/s12257-011-0283-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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28
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Ye Z, Berson RE. Kinetic modeling of cellulose hydrolysis with first order inactivation of adsorbed cellulase. BIORESOURCE TECHNOLOGY 2011; 102:11194-11199. [PMID: 22001057 DOI: 10.1016/j.biortech.2011.09.044] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 08/30/2011] [Accepted: 09/13/2011] [Indexed: 05/31/2023]
Abstract
Enzymatic hydrolysis involves complex interaction between enzyme, substrate, and the reaction environment, and the complete mechanism is still unknown. Further, glucose release slows significantly as the reaction proceeds. A model based on Langmuir binding kinetics that incorporates inactivation of adsorbed cellulase was developed that predicts product formation within 10% of experimental results for two substrates. A key premise of the model, with experimental validation, suggests that V(max) decreases as a function of time due to loss of total available enzyme as adsorbed cellulases become inactivated. Rate constants for product formation and enzyme inactivation were comparable to values reported elsewhere. A value of k(2)/K(m) that is several orders of magnitude lower than the rate constant for the diffusion-controlled encounter of enzyme and substrate, along with similar parameter values between substrates, implies a common but undefined rate-limiting step associated with loss of enzyme activity likely exists in the pathway of cellulose hydrolysis.
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Affiliation(s)
- Zhuoliang Ye
- Department of Chemical Engineering, University of Louisville, Louisville, KY 40292, USA
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29
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Thermostable Bacterial Endoglucanases Mined from Swiss-Prot Database. Appl Biochem Biotechnol 2011; 165:1473-84. [DOI: 10.1007/s12010-011-9368-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 09/02/2011] [Indexed: 10/17/2022]
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30
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Ye Z, Lane AN, Willing GA, Berson RE. Scaled-up separation of cellobiohydrolase1 from a cellulase mixture by ion-exchange chromatography. Biotechnol Prog 2011; 27:1644-52. [DOI: 10.1002/btpr.696] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 04/27/2011] [Indexed: 11/10/2022]
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31
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Suchy M, Linder MB, Tammelin T, Campbell JM, Vuorinen T, Kontturi E. Quantitative assessment of the enzymatic degradation of amorphous cellulose by using a quartz crystal microbalance with dissipation monitoring. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:8819-28. [PMID: 21699170 DOI: 10.1021/la2014418] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The systematic evaluation of the degradation of an amorphous cellulose film by a monocomponent endoglucanase (EG I) by using a quartz crystal microbalance with dissipation monitoring (QCM-D) identified several important aspects relevant to the study the kinetics of cellulose degradation by enzymes. It was demonstrated that, to properly evaluate the mechanism of action, steady state conditions in the experimental set up need to be reached. Rinsing or diluting the enzyme, as well as concentration of the enzyme, can have a pronounced effect on the hydrolysis. Quantification of the actual hydrolysis was carried out by measuring the film thickness reduction by atomic force microscopy after the enzymatic treatment. The values correlated well with the frequency data obtained by QCM-D measurement for corresponding films. This demonstrated that the evaluation of hydrolysis by QCM-D can be done quantitatively. Tuning of the initial thickness of films enabled variation of the volume of substrate available for hydrolysis which was then utilized in establishing a correlation between substrate volume and hydrolytic activity of EG I as measured by QCM-D. It was shown that, although the amount of substrate affects the absolute rate of hydrolysis, the relative rate of hydrolysis does not depend on the initial amount of substrate in steady state system. With this experimental setup it was also possible to demonstrate the impact of concentration on crowding of enzyme and subsequent hydrolysis efficiency. This effort also shows the action of EG I on a fully amorphous substrate as observed by QCM-D. The enzyme was shown to work uniformly within the whole volume of swollen film, however being unable to fully degrade the amorphous film.
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Affiliation(s)
- Miro Suchy
- Department of Forest Products Technology, School of Chemical Technology, Aalto University, Aalto, Finland
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32
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Praestgaard E, Elmerdahl J, Murphy L, Nymand S, McFarland KC, Borch K, Westh P. A kinetic model for the burst phase of processive cellulases. FEBS J 2011; 278:1547-60. [DOI: 10.1111/j.1742-4658.2011.08078.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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33
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Moran-Mirabal JM, Bolewski JC, Walker LP. Reversibility and binding kinetics of Thermobifida fusca cellulases studied through fluorescence recovery after photobleaching microscopy. Biophys Chem 2011; 155:20-8. [PMID: 21396764 DOI: 10.1016/j.bpc.2011.02.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 02/14/2011] [Accepted: 02/14/2011] [Indexed: 11/26/2022]
Abstract
Cellulases are enzymes capable of depolymerizing cellulose. Understanding their interactions with cellulose can improve biomass saccharification and enzyme recycling in biofuel production. This paper presents a study on binding and binding reversibility of Thermobifida fusca cellulases Cel5A, Cel6B, and Cel9A bound onto Bacterial Microcrystalline Cellulose. Cellulase binding was assessed through fluorescence recovery after photobleaching (FRAP) at 23, 34, and 45 °C. It was found that cellulase binding is only partially reversible. For processive cellulases Cel6B and Cel9A, an increase in temperature resulted in a decrease of the fraction of cellulases reversibly bound, while for endocellulase Cel5A this fraction remained constant. Kinetic parameters were obtained by fitting the FRAP curves to a binding-dominated model. The unbinding rate constants obtained for all temperatures were highest for Cel5A and lowest for Cel9A. The results presented demonstrate the usefulness of FRAP to access the fast binding kinetics characteristic of cellulases operating at their optimal temperature.
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Affiliation(s)
- Jose M Moran-Mirabal
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA.
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34
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Wang Z, Xu JH, Feng H, Qi H. Fractal kinetic analysis of polymers/nonionic surfactants to eliminate lignin inhibition in enzymatic saccharification of cellulose. BIORESOURCE TECHNOLOGY 2011; 102:2890-2896. [PMID: 21093257 DOI: 10.1016/j.biortech.2010.10.132] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 10/25/2010] [Accepted: 10/26/2010] [Indexed: 05/30/2023]
Abstract
The profile of enzymatic saccharification of Avicel in the presence and absence of lignin has been described with a fractal kinetic model (Wang and Feng, 2010), in which the retarded hydrolysis rate of enzymatic saccharification of cellulose has been represented with a fractal exponent. The lignin inhibition in the enzymatic saccharification of cellulose is indexed by the increase of fractal exponent, which can not be fully counterbalanced by high cellulase loading due to the high fractal exponent at high cellulase loading. On the contrary, fractal kinetic analysis indicates that an addition of some nonionic surfactant/polymers decrease the fractal exponent to the original values of enzymatic saccharification of Avicel without lignin and the corresponding toxicity of nonionic surfactants/polymers on the consecutive ethanol fermentation strain Saccharomyces cerevisiae is also examined.
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Affiliation(s)
- Zhilong Wang
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, PR China.
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35
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Jäger G, Wu Z, Garschhammer K, Engel P, Klement T, Rinaldi R, Spiess AC, Büchs J. Practical screening of purified cellobiohydrolases and endoglucanases with α-cellulose and specification of hydrodynamics. BIOTECHNOLOGY FOR BIOFUELS 2010; 3:18. [PMID: 20718965 PMCID: PMC2936879 DOI: 10.1186/1754-6834-3-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Accepted: 08/18/2010] [Indexed: 05/08/2023]
Abstract
BACKGROUND It is important to generate biofuels and society must be weaned from its dependency on fossil fuels. In order to produce biofuels, lignocellulose is pretreated and the resulting cellulose is hydrolyzed by cellulases such as cellobiohydrolases (CBH) and endoglucanases (EG). Until now, the biofuel industry has usually applied impractical celluloses to screen for cellulases capable of degrading naturally occurring, insoluble cellulose. This study investigates how these cellulases adsorb and hydrolyze insoluble α-cellulose - considered to be a more practical substrate which mimics the alkaline-pretreated biomass used in biorefineries. Moreover, this study investigates how hydrodynamics affects cellulase adsorption and activity onto α-cellulose. RESULTS First, the cellulases CBH I, CBH II, EG I and EG II were purified from Trichoderma reesei and CBH I and EG I were utilized in order to study and model the adsorption isotherms (Langmuir) and kinetics (pseudo-first-order). Second, the adsorption kinetics and cellulase activities were studied under different hydrodynamic conditions, including liquid mixing and particle suspension. Third, in order to compare α-cellulose with three typically used celluloses, the exact cellulase activities towards all four substrates were measured.It was found that, using α-cellulose, the adsorption models fitted to the experimental data and yielded parameters comparable to those for filter paper. Moreover, it was determined that higher shaking frequencies clearly improved the adsorption of cellulases onto α-cellulose and thus bolstered their activity. Complete suspension of α-cellulose particles was the optimal operating condition in order to ensure efficient cellulase adsorption and activity. Finally, all four purified cellulases displayed comparable activities only on insoluble α-cellulose. CONCLUSIONS α-Cellulose is an excellent substrate to screen for CBHs and EGs. This current investigation shows in detail, for the first time, the adsorption of purified cellulases onto α-cellulose, the effect of hydrodynamics on cellulase adsorption and the correlation between the adsorption and the activity of cellulases at different hydrodynamic conditions. Complete suspension of the substrate has to be ensured in order to optimize the cellulase attack. In the future, screenings should be conducted with α-cellulose so that proper cellulases are selected to best hydrolyze the real alkaline-pretreated biomass used in biorefineries.
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Affiliation(s)
- Gernot Jäger
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany
| | - Zhuojun Wu
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany
| | - Kerstin Garschhammer
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany
| | - Philip Engel
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany
| | - Tobias Klement
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany
| | - Roberto Rinaldi
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Antje C Spiess
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany
| | - Jochen Büchs
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany
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36
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Jalak J, Väljamäe P. Mechanism of initial rapid rate retardation in cellobiohydrolase catalyzed cellulose hydrolysis. Biotechnol Bioeng 2010; 106:871-83. [DOI: 10.1002/bit.22779] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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37
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Rich RL, Myszka DG. Grading the commercial optical biosensor literature-Class of 2008: 'The Mighty Binders'. J Mol Recognit 2010; 23:1-64. [PMID: 20017116 DOI: 10.1002/jmr.1004] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Optical biosensor technology continues to be the method of choice for label-free, real-time interaction analysis. But when it comes to improving the quality of the biosensor literature, education should be fundamental. Of the 1413 articles published in 2008, less than 30% would pass the requirements for high-school chemistry. To teach by example, we spotlight 10 papers that illustrate how to implement the technology properly. Then we grade every paper published in 2008 on a scale from A to F and outline what features make a biosensor article fabulous, middling or abysmal. To help improve the quality of published data, we focus on a few experimental, analysis and presentation mistakes that are alarmingly common. With the literature as a guide, we want to ensure that no user is left behind.
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Affiliation(s)
- Rebecca L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
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38
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Empirical Evaluation of Inhibitory Product, Substrate, and Enzyme Effects During the Enzymatic Saccharification of Lignocellulosic Biomass. Appl Biochem Biotechnol 2010; 161:468-82. [DOI: 10.1007/s12010-010-8931-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2009] [Accepted: 02/10/2010] [Indexed: 11/27/2022]
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39
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Kumar R, Wyman CE. Does change in accessibility with conversion depend on both the substrate and pretreatment technology? BIORESOURCE TECHNOLOGY 2009; 100:4193-202. [PMID: 19398329 DOI: 10.1016/j.biortech.2008.11.058] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2008] [Revised: 11/11/2008] [Accepted: 11/20/2008] [Indexed: 05/17/2023]
Abstract
The accessibility of cellulase and xylanase enzymes to glucan and xylan, respectively, and its change with conversion were measured for pure Avicel glucan and poplar solids that had been pretreated by ammonia fiber expansion (AFEX), ammonia recycled percolation (ARP), dilute acid, and lime. Avicel and pretreated solids were digested to various degrees by cellulase together with beta-glucosidase enzymes and then cleaned of residual protein via a biological method using Protease. Glucan accessibility was determined by purified CBHI (Cel7A) adsorption at 4 degrees C, and 4 and 24 h hydrolysis yields were determined for solids loading containing equal amounts of glucan (1.0% w/v) and lignin (1.0% w/v), in two separate sets of experiments. Consistent with our previous study and in contrast to some in the literature, little change in glucan accessibility was observed with conversion for Avicel, but glucan and xylan accessibility for real biomass varied with the type of pretreatment. For example, AFEX pretreated solids showed a negligible change in glucan accessibility for conversion up to 90%, although xylan accessibility seemed to decline first and then remained constant. On the other hand, a substantial decline in glucan and xylan accessibility with conversion was observed for lime pretreated poplar solids, as shown by initial hydrolysis rates. Yet, an increase in CBHI adsorption with conversion for lime pretreated poplar solids suggested the opposite trend, possibly due to increased lignin exposure and/or reduced effectiveness of adsorbed enzyme.
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Affiliation(s)
- Rajeev Kumar
- Thayer School of Engineering, Dartmouth College, New Hampshire 03755, USA
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