1
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A steady-state approach for inhibition of heterogeneous enzyme reactions. Biochem J 2020; 477:1971-1982. [PMID: 32391552 DOI: 10.1042/bcj20200083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/07/2020] [Accepted: 05/11/2020] [Indexed: 02/02/2023]
Abstract
The kinetic theory of enzymes that modify insoluble substrates is still underdeveloped, despite the prevalence of this type of reaction both in vivo and industrial applications. Here, we present a steady-state kinetic approach to investigate inhibition occurring at the solid-liquid interface. We propose to conduct experiments under enzyme excess (E0 ≫ S0), i.e. the opposite limit compared with the conventional Michaelis-Menten framework. This inverse condition is practical for insoluble substrates and elucidates how the inhibitor reduces enzyme activity through binding to the substrate. We claim that this type of inhibition is common for interfacial enzyme reactions because substrate accessibility is low, and we show that it can be analyzed by experiments and rate equations that are analogous to the conventional approach, except that the roles of enzyme and substrate have been swapped. To illustrate the approach, we investigated the major cellulases from Trichoderma reesei (Cel6A and Cel7A) acting on insoluble cellulose. As model inhibitors, we used catalytically inactive variants of Cel6A and Cel7A. We made so-called inverse Michaelis-Menten curves at different concentrations of inhibitors and found that a new rate equation accounted well for the data. In most cases, we found a mixed type of surface-site inhibition mechanism, and this probably reflected that the inhibitor both competed with the enzyme for the productive binding-sites (competitive inhibition) and hampered the processive movement on the surface (uncompetitive inhibition). These results give new insights into the complex interplay of Cel7A and Cel6A on cellulose and the approach may be applicable to other heterogeneous enzyme reactions.
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2
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Baig KS. Interaction of enzymes with lignocellulosic materials: causes, mechanism and influencing factors. BIORESOUR BIOPROCESS 2020. [DOI: 10.1186/s40643-020-00310-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AbstractFor the production of biofuel (bioethanol), enzymatic adsorption onto a lignocellulosic biomass surface is a prior condition for the enzymatic hydrolysis process to occur. Lignocellulosic substances are mainly composed of cellulose, hemicellulose and lignin. The polysaccharide matrix (cellulose and hemicellulose) is capable of producing bioethanol. Therefore, lignin is removed or its concentration is reduced from the adsorption substrates by pretreatments. Selected enzymes are used for the production of reducing sugars from cellulosic materials, which in turn are converted to bioethanol. Adsorption of enzymes onto the substrate surface is a complicated process. A large number of research have been performed on the adsorption process, but little has been done to understand the mechanism of adsorption process. This article reviews the mechanisms of adsorption of enzymes onto the biomass surfaces. A conceptual adsorption mechanism is presented which will fill the gaps in literature and help researchers and industry to use adsorption more efficiently. The process of enzymatic adsorption starts with the reciprocal interplay of enzymes and substrates and ends with the establishment of molecular and cellular binding. The kinetics of an enzymatic reaction is almost the same as that of a characteristic chemical catalytic reaction. The influencing factors discussed in detail are: surface characteristics of the participating materials, the environmental factors, such as the associated flow conditions, temperature, concentration, etc. Pretreatment of lignocellulosic materials and optimum range of shear force and temperature for getting better results of adsorption are recommended.
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3
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Gu Y, Zheng F, Wang Y, Su X, Bai Y, Yao B, Huang H, Luo H. Characterization of two thermophilic cellulases from Talaromyces leycettanus JCM12802 and their synergistic action on cellulose hydrolysis. PLoS One 2019; 14:e0224803. [PMID: 31730665 PMCID: PMC6857856 DOI: 10.1371/journal.pone.0224803] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/22/2019] [Indexed: 11/29/2022] Open
Abstract
Talaromyces leycettanus JCM12802 is a great producer of thermophilic glycoside hydrolases (GHs). In this study, two cellulases (TlCel5A and TlCel6A) belonging to GH5 and GH6 respectively were expressed in Pichia pastoris and functionally characterized. The enzymes had acidic and thermophilic properties, showing optimal activities at pH 3.5–4.5 and 75–80°C, and retained stable at temperatures up to 60°C and over a broad pH range of 2.0−8.0. TlCel5A and TlCel6A acted against several cellulose substrates with varied activities (3,101.1 vs. 92.9 U/mg to barley β-glucan, 3,905.6 U/mg vs. 109.0 U/mg to lichenan, and 840.3 and 0.09 U/mg to CMC-Na). When using Avicel, phosphoric acid swollen cellulose (PASC) or steam-exploded corn straw (SECS) as the substrate, combination of TlCel5A and TlCel6A showed significant synergistic action, releasing more reduced sugars (1.08–2.87 mM) than the individual enzymes. These two cellulases may represent potential enzyme additives for the efficient biomass conversion and bioethanol production.
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Affiliation(s)
- Yuan Gu
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People’s Republic of China
| | - Fei Zheng
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People’s Republic of China
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, People’s Republic of China
| | - Yuan Wang
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People’s Republic of China
| | - Xiaoyun Su
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People’s Republic of China
| | - Yingguo Bai
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People’s Republic of China
| | - Bin Yao
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People’s Republic of China
| | - Huoqing Huang
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People’s Republic of China
- * E-mail: (HL); (HH)
| | - Huiying Luo
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, People’s Republic of China
- * E-mail: (HL); (HH)
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4
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Lu M, Li J, Han L, Xiao W. An aggregated understanding of cellulase adsorption and hydrolysis for ball-milled cellulose. BIORESOURCE TECHNOLOGY 2019; 273:1-7. [PMID: 30368157 DOI: 10.1016/j.biortech.2018.10.037] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/13/2018] [Accepted: 10/15/2018] [Indexed: 05/22/2023]
Abstract
This study evaluated the effects of physicochemical properties of a series of ball-milled cellulose on cellulase adsorption and glucose yield. The relationship between cellulase adsorption and initial hydrolysis rate was also discussed. We found that hydrophobicity and surface charge are the key factors affecting cellulase adsorption on ball-milled cellulose. The results demonstrated that glucose yield had a positive correlation with specific surface area, while showed a negative correlation with particle size, degree of polymerization and crystallinity. Among these properties, specific surface area and crystallinity are the key factors affecting glucose yield. As ball milling progressed, cellulose showed lower enzyme adsorption capacity/amount of bound enzyme during initial stage of hydrolysis, but had higher initial hydrolysis rate. The enhanced rate is attributed to the fact that the amorphous region produced by ball milling reduces the free energy required for decrystallization thus increases the catalytic efficiency of the bound enzyme.
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Affiliation(s)
- Minsheng Lu
- Laboratory of Biomass and Bioprocessing Engineering, College of Engineering, China Agricultural University, Beijing 100083, PR China.
| | - Junbao Li
- Laboratory of Biomass and Bioprocessing Engineering, College of Engineering, China Agricultural University, Beijing 100083, PR China.
| | - Lujia Han
- Laboratory of Biomass and Bioprocessing Engineering, College of Engineering, China Agricultural University, Beijing 100083, PR China.
| | - Weihua Xiao
- Laboratory of Biomass and Bioprocessing Engineering, College of Engineering, China Agricultural University, Beijing 100083, PR China.
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5
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Karnaouri A, Topakas E, Matsakas L, Rova U, Christakopoulos P. Fine-Tuned Enzymatic Hydrolysis of Organosolv Pretreated Forest Materials for the Efficient Production of Cellobiose. Front Chem 2018; 6:128. [PMID: 29725590 PMCID: PMC5917092 DOI: 10.3389/fchem.2018.00128] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/04/2018] [Indexed: 11/23/2022] Open
Abstract
Non-digestible oligosaccharides (NDOs) are likely prebiotic candidates that have been related to the prevention of intestinal infections and other disorders for both humans and animals. Lignocellulosic biomass is the largest carbon source in the biosphere, therefore cello-oligosacharides (COS), especially cellobiose, are potentially the most widely available choice of NDOs. Production of COS and cellobiose with enzymes offers numerous benefits over acid-catalyzed processes, as it is milder, environmentally friendly and produces fewer by-products. Cellobiohydrolases (CBHs) and a class of endoglucanases (EGs), namely processive EGs, are key enzymes for the production of COS, as they have higher preference toward glycosidic bonds near the end of cellulose chains and are able to release soluble products. In this work, we describe the heterologous expression and characterization of two CBHs from the filamentous fungus Thermothelomyces thermophila, as well as their synergism with proccessive EGs for cellobiose release from organosolv pretreated spruce and birch. The properties, inhibition kinetics and substrate specific activities for each enzyme are described in detail. The results show that a combination of EGs belonging to Glycosyl hydrolase families 5, 6, and 9, with a CBHI and CBHII in appropriate proportions, can enhance the production of COS from forest materials, underpinning the potential of these biocatalysts in the production of NDOs.
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Affiliation(s)
- Anthi Karnaouri
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
| | - Evangelos Topakas
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.,Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Leonidas Matsakas
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
| | - Ulrika Rova
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
| | - Paul Christakopoulos
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
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6
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Badino SF, Kari J, Christensen SJ, Borch K, Westh P. Direct kinetic comparison of the two cellobiohydrolases Cel6A and Cel7A from Hypocrea jecorina. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1739-1745. [DOI: 10.1016/j.bbapap.2017.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/25/2017] [Accepted: 08/14/2017] [Indexed: 01/17/2023]
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7
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Badino SF, Christensen SJ, Kari J, Windahl MS, Hvidt S, Borch K, Westh P. Exo-exo synergy between Cel6A and Cel7A fromHypocrea jecorina: Role of carbohydrate binding module and the endo-lytic character of the enzymes. Biotechnol Bioeng 2017; 114:1639-1647. [DOI: 10.1002/bit.26276] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/17/2017] [Accepted: 02/21/2017] [Indexed: 01/08/2023]
Affiliation(s)
- Silke F. Badino
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
| | - Stefan J. Christensen
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
| | - Jeppe Kari
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
| | - Michael S. Windahl
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
- Novozymes A/S; Bagsvaerd Denmark
| | - Søren Hvidt
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
| | | | - Peter Westh
- Research Unit for Functional Biomaterials; Department of Science and Environment; INM; Roskilde University; 1 Universitetsvej, Build. 28C, DK-4000 Roskilde Denmark
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8
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Shi J, Wu D, Zhang L, Simmons BA, Singh S, Yang B, Wyman CE. Dynamic changes of substrate reactivity and enzyme adsorption on partially hydrolyzed cellulose. Biotechnol Bioeng 2016; 114:503-515. [PMID: 27617791 DOI: 10.1002/bit.26180] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/29/2016] [Accepted: 09/05/2016] [Indexed: 11/10/2022]
Abstract
The enzymatic hydrolysis of cellulose is a thermodynamically challenging catalytic process that is influenced by both substrate-related and enzyme-related factors. In this study, a proteolysis approach was applied to recover and clean the partially converted cellulose at the different stages of enzymatic hydrolysis to monitor the hydrolysis rate as a function of substrate reactivity/accessibility and investigate surface characteristics of the partially converted cellulose. Enzyme-substrate interactions between individual key cellulase components from wild-type Trichoderma reesei and partially converted cellulose were followed and correlated to the enzyme adsorption capacity and dynamic sugar release. Results suggest that cellobiohydrolase CBH1 (Cel7A) and endoglucanases EG2 (Cel5A) adsorption capacities decreased as cellulose was progressively hydrolyzed, likely due to the "depletion" of binding sites. Furthermore, the degree of synergism between CBH1 and EG2 varied depending on the enzyme loading and the substrates. The results provide a better understanding of the relationship between dynamic change of substrate features and the functionality of various cellulase components during enzymatic hydrolysis. Biotechnol. Bioeng. 2017;114: 503-515. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Jian Shi
- Center for Environmental Research and Technology, University of California, 1084 Columbia Avenue, Riverside, CA 92507.,Deconstruction Division, Joint BioEnergy Institute, Emeryville, California.,Department of Biosystems and Agricultural Engineering, University of Kentucky, Lexington, Kentucky
| | - Dong Wu
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, California.,Biological and Materials Science Center, Sandia National Laboratories, Livermore, California
| | - Libing Zhang
- Bioproducts, Sciences and Engineering Laboratory, Department of Biological Systems Engineering, Washington State University, Richland, Washington
| | - Blake A Simmons
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, California
| | - Seema Singh
- Deconstruction Division, Joint BioEnergy Institute, Emeryville, California.,Biological and Materials Science Center, Sandia National Laboratories, Livermore, California
| | - Bin Yang
- Center for Environmental Research and Technology, University of California, 1084 Columbia Avenue, Riverside, CA 92507.,Bioproducts, Sciences and Engineering Laboratory, Department of Biological Systems Engineering, Washington State University, Richland, Washington
| | - Charles E Wyman
- Center for Environmental Research and Technology, University of California, 1084 Columbia Avenue, Riverside, CA 92507.,Department of Chemical and Environmental Engineering, Bourns College of Engineering, Riverside, California.,BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee
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9
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Xin D, Yang M, Chen X, Zhang J. The access of Trichoderma reesei 6A to cellulose is blocked by isolated hemicelluloses and their derivatives in biomass hydrolysis. RSC Adv 2016. [DOI: 10.1039/c6ra14617a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mannan inhibited action of CBHII from Trichoderma reesei by retarding the adsorption of CBHII to cellulose.
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Affiliation(s)
- Donglin Xin
- College of Forestry
- Northwest A&F University
- Yangling 712100
- China
| | - Ming Yang
- College of Forestry
- Northwest A&F University
- Yangling 712100
- China
| | - Xiang Chen
- College of Forestry
- Northwest A&F University
- Yangling 712100
- China
| | - Junhua Zhang
- College of Forestry
- Northwest A&F University
- Yangling 712100
- China
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10
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Hamid SBA, Islam MM, Das R. Cellulase biocatalysis: key influencing factors and mode of action. CELLULOSE 2015; 22:2157-2182. [DOI: 10.1007/s10570-015-0672-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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11
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Nag A, Sprague MA, Griggs AJ, Lischeske JJ, Stickel JJ, Mittal A, Wang W, Johnson DK. Parameter determination and validation for a mechanistic model of the enzymatic saccharification of cellulose-Iβ. Biotechnol Prog 2015; 31:1237-48. [PMID: 26081044 DOI: 10.1002/btpr.2122] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/08/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Ambarish Nag
- Computational Science Center; National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401
| | - Michael A. Sprague
- Computational Science Center; National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401
| | - Andrew J. Griggs
- National Bioenergy Center; National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401
| | - James J. Lischeske
- National Bioenergy Center; National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401
| | - Jonathan J. Stickel
- National Bioenergy Center; National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401
| | - Ashutosh Mittal
- Biosciences Center; National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401
| | - Wei Wang
- Biosciences Center; National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401
| | - David K. Johnson
- Biosciences Center; National Renewable Energy Laboratory; 15013 Denver West Parkway Golden CO 80401
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12
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Lakhundi S, Siddiqui R, Khan NA. Cellulose degradation: a therapeutic strategy in the improved treatment of Acanthamoeba infections. Parasit Vectors 2015; 8:23. [PMID: 25586209 PMCID: PMC4300153 DOI: 10.1186/s13071-015-0642-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 01/05/2015] [Indexed: 11/10/2022] Open
Abstract
Acanthamoeba is an opportunistic free-living amoeba that can cause blinding keratitis and fatal brain infection. Early diagnosis, followed by aggressive treatment is a pre-requisite in the successful treatment but even then the prognosis remains poor. A major drawback during the course of treatment is the ability of the amoeba to enclose itself within a shell (a process known as encystment), making it resistant to chemotherapeutic agents. As the cyst wall is partly made of cellulose, thus cellulose degradation offers a potential therapeutic strategy in the effective targeting of trophozoite encased within the cyst walls. Here, we present a comprehensive report on the structure of cellulose and cellulases, as well as known cellulose degradation mechanisms with an eye to target the Acanthamoeba cyst wall. The disruption of the cyst wall will make amoeba (concealed within) susceptible to chemotherapeutic agents, and at the very least inhibition of the excystment process will impede infection recurrence, as we bring these promising drug targets into focus so that they can be explored to their fullest.
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Affiliation(s)
- Sahreena Lakhundi
- Department of Biological and Biomedical Sciences, Aga Khan University, Stadium Road, Karachi, Pakistan.
| | - Ruqaiyyah Siddiqui
- Department of Biological and Biomedical Sciences, Aga Khan University, Stadium Road, Karachi, Pakistan.
| | - Naveed Ahmed Khan
- Department of Biological and Biomedical Sciences, Aga Khan University, Stadium Road, Karachi, Pakistan.
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13
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Harrison MD, Zhang Z, Shand K, Chong BF, Nichols J, Oeller P, O’Hara IM, Doherty WOS, Dale JL. The combination of plant-expressed cellobiohydrolase and low dosages of cellulases for the hydrolysis of sugar cane bagasse. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:131. [PMID: 25254073 PMCID: PMC4172943 DOI: 10.1186/s13068-014-0131-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 08/27/2014] [Indexed: 05/18/2023]
Abstract
BACKGROUND The expression of biomass-degrading enzymes (such as cellobiohydrolases) in transgenic plants has the potential to reduce the costs of biomass saccharification by providing a source of enzymes to supplement commercial cellulase mixtures. Cellobiohydrolases are the main enzymes in commercial cellulase mixtures. In the present study, a cellobiohydrolase was expressed in transgenic corn stover leaf and assessed as an additive for two commercial cellulase mixtures for the saccharification of pretreated sugar cane bagasse obtained by different processes. RESULTS Recombinant cellobiohydrolase in the senescent leaves of transgenic corn was extracted using a simple buffer with no concentration step. The extract significantly enhanced the performance of Celluclast 1.5 L (a commercial cellulase mixture) by up to fourfold on sugar cane bagasse pretreated at the pilot scale using a dilute sulfuric acid steam explosion process compared to the commercial cellulase mixture on its own. Also, the extracts were able to enhance the performance of Cellic CTec2 (a commercial cellulase mixture) up to fourfold on a range of residues from sugar cane bagasse pretreated at the laboratory (using acidified ethylene carbonate/ethylene glycol, 1-butyl-3-methylimidazolium chloride, and ball-milling) and pilot (dilute sodium hydroxide and glycerol/hydrochloric acid steam explosion) scales. We have demonstrated using tap water as a solvent (under conditions that mimic an industrial process) extraction of about 90% recombinant cellobiohydrolase from senescent, transgenic corn stover leaf that had minimal tissue disruption. CONCLUSIONS The accumulation of recombinant cellobiohydrolase in senescent, transgenic corn stover leaf is a viable strategy to reduce the saccharification cost associated with the production of fermentable sugars from pretreated biomass. We envisage an industrial-scale process in which transgenic plants provide both fibre and biomass-degrading enzymes for pretreatment and enzymatic hydrolysis, respectively.
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Affiliation(s)
- Mark D Harrison
- />Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
- />Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
| | - Zhanying Zhang
- />Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
- />Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
| | - Kylie Shand
- />Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
- />Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
| | - Barrie Fong Chong
- />Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
- />Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
| | - Jason Nichols
- />Syngenta Biotechnology Inc., Research Triangle Park, 3054 East Cornwallis Road, Durham, NC 27709-2257 USA
| | - Paul Oeller
- />Syngenta Biotechnology Inc., Research Triangle Park, 3054 East Cornwallis Road, Durham, NC 27709-2257 USA
| | - Ian M O’Hara
- />Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
- />Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
| | - William OS Doherty
- />Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
| | - James L Dale
- />Syngenta Centre for Sugarcane Biofuels Development, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
- />Centre for Tropical Crops and Biocommodities, Queensland University of Technology, GPO Box 2432, 2 George Street, Brisbane, Queensland 4001 Australia
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14
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Hong J, Yang H, Zhang K, Liu C, Zou S, Zhang M. Development of a cellulolytic Saccharomyces cerevisiae strain with enhanced cellobiohydrolase activity. World J Microbiol Biotechnol 2014; 30:2985-93. [PMID: 25164958 DOI: 10.1007/s11274-014-1726-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 08/20/2014] [Indexed: 11/27/2022]
Abstract
Consolidated bioprocessing (CBP) is a promising technology for lignocellulosic ethanol production, and the key is the engineering of a microorganism that can efficiently utilize cellulose. Development of Saccharomyces cerevisiae for CBP requires high level expression of cellulases, particularly cellobiohydrolases (CBH). In this study, to construct a CBP-enabling yeast with enhanced CBH activity, three cassettes containing constitutively expressed CBH-encoding genes (cbh1 from Aspergillus aculeatus, cbh1 and cbh2 from Trichoderma reesei) were constructed. T. reesei eg2, A. aculeatus bgl1, and the three CBH-encoding genes were then sequentially integrated into the S. cerevisiae W303-1A chromosome via δ-sequence-mediated integration. The resultant strains W1, W2, and W3, expressing uni-, bi-, and trifunctional cellulases, respectively, exhibited corresponding cellulase activities. Furthermore, both the activities and glucose producing activity ascended. The growth test on cellulose containing plates indicated that CBH was a necessary component for successful utilization of crystalline cellulose. The three recombinant strains and the control strains W303-1A and AADY were evaluated in acid- and alkali-pretreated corncob containing media with 5 FPU exogenous cellulase/g biomass loading. The highest ethanol titer (g/l) within 7 days was 5.92 ± 0.51, 18.60 ± 0.81, 28.20 ± 0.84, 1.40 ± 0.12, and 2.12 ± 0.35, respectively. Compared with the control strains, W3 efficiently fermented pretreated corncob to ethanol. To our knowledge, this is the first study aimed at creating cellulolytic yeast with enhanced CBH activity by integrating three types of CBH-encoding gene with a strong constitutive promoter Ptpi.
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Affiliation(s)
- Jiefang Hong
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin, 300072, China
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15
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Trudeau DL, Lee TM, Arnold FH. Engineered thermostable fungal cellulases exhibit efficient synergistic cellulose hydrolysis at elevated temperatures. Biotechnol Bioeng 2014; 111:2390-7. [DOI: 10.1002/bit.25308] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 05/28/2014] [Accepted: 06/02/2014] [Indexed: 11/07/2022]
Affiliation(s)
- Devin L. Trudeau
- Division of Chemistry and Chemical Engineering; California Institute of Technology; Pasadena California
| | - Toni M. Lee
- Division of Biology and Bioengineering; California Institute of Technology; Pasadena California
| | - Frances H. Arnold
- Division of Chemistry and Chemical Engineering; California Institute of Technology; Pasadena California
- Division of Biology and Bioengineering; California Institute of Technology; Pasadena California
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16
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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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17
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Shang BZ, Chu JW. Kinetic Modeling at Single-Molecule Resolution Elucidates the Mechanisms of Cellulase Synergy. ACS Catal 2014. [DOI: 10.1021/cs500126q] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Barry Z. Shang
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
| | - Jhih-Wei Chu
- Department
of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
- Department
of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan, ROC
- Institute
of Bioinformatics and Systems Biology, National Chiao Tung University, Hsinchu, Taiwan, ROC
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18
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Rahikainen JL, Moilanen U, Nurmi-Rantala S, Lappas A, Koivula A, Viikari L, Kruus K. Effect of temperature on lignin-derived inhibition studied with three structurally different cellobiohydrolases. BIORESOURCE TECHNOLOGY 2013; 146:118-125. [PMID: 23920120 DOI: 10.1016/j.biortech.2013.07.069] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 07/13/2013] [Accepted: 07/15/2013] [Indexed: 05/08/2023]
Abstract
Non-productive enzyme adsorption onto lignin inhibits enzymatic hydrolysis of lignocellulosic biomass. Three cellobiohydrolases, Trichoderma reesei Cel7A (TrCel7A) and two engineered fusion enzymes, with distinctive modular structures and temperature stabilities were employed to study the effect of temperature on inhibition arising from non-productive cellulase adsorption. The fusion enzymes, TeCel7A-CBM1 and TeCel7A-CBM3, were composed of a thermostable Talaromyces emersonii Cel7A (TeCel7A) catalytic domain fused to a carbohydrate-binding module (CBM) either from family 1 or from family 3. With all studied enzymes, increase in temperature was found to increase the inhibitory effect of supplemented lignin in the enzymatic hydrolysis of microcrystalline cellulose. However, for the different enzymes, lignin-derived inhibition emerged at different temperatures. Low binding onto lignin and thermostable structure were characteristic for the most lignin-tolerant enzyme, TeCel7A-CBM1, whereas TrCel7A was most susceptible to lignin especially at elevated temperature (55 °C).
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Affiliation(s)
| | - Ulla Moilanen
- University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Helsinki, Finland
| | | | - Angelos Lappas
- Center for Research and Technology Hellas (CERTH), Chemical Process Engineering Research Institute, P.O. Box 60361, 57001 Thermi-Thessaloniki, Greece
| | - Anu Koivula
- VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Finland
| | - Liisa Viikari
- University of Helsinki, P.O. Box 27, 00014 University of Helsinki, Helsinki, Finland
| | - Kristiina Kruus
- VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Finland.
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19
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Wu I, Heel T, Arnold FH. Role of cysteine residues in thermal inactivation of fungal Cel6A cellobiohydrolases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:1539-44. [PMID: 23676789 DOI: 10.1016/j.bbapap.2013.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 05/01/2013] [Accepted: 05/06/2013] [Indexed: 10/26/2022]
Abstract
Numerous protein engineering studies have focused on increasing the thermostability of fungal cellulases to improve production of fuels and chemicals from lignocellulosic feedstocks. However, the engineered enzymes still undergo thermal inactivation at temperatures well below the inactivation temperatures of hyperthermophilic cellulases. In this report, we investigated the role of free cysteines in the thermal inactivation of wild-type and engineered fungal family 6 cellobiohydrolases (Cel6A). The mechanism of thermal inactivation of Cel6A is consistent with disulfide bond degradation and thiol-disulfide exchange. Circular dichroism spectroscopy revealed that a thermostable variant lacking free cysteines refolds to a native-like structure and retains activity after heat treatment over the pH range 5-9. Whereas conserved disulfide bonds are essential for retaining activity after heat treatment, free cysteines contribute to irreversible thermal inactivation in engineered thermostable Cel6A as well as Cel6A from Hypocrea jecorina and Humicola insolens.
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Affiliation(s)
- Indira Wu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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20
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Insights into exo- and endoglucanase activities of family 6 glycoside hydrolases from Podospora anserina. Appl Environ Microbiol 2013; 79:4220-9. [PMID: 23645193 DOI: 10.1128/aem.00327-13] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The ascomycete Podospora anserina is a coprophilous fungus that grows at late stages on droppings of herbivores. Its genome encodes a large diversity of carbohydrate-active enzymes. Among them, four genes encode glycoside hydrolases from family 6 (GH6), the members of which comprise putative endoglucanases and exoglucanases, some of them exerting important functions for biomass degradation in fungi. Therefore, this family was selected for functional analysis. Three of the enzymes, P. anserina Cel6A (PaCel6A), PaCel6B, and PaCel6C, were functionally expressed in the yeast Pichia pastoris. All three GH6 enzymes hydrolyzed crystalline and amorphous cellulose but were inactive on hydroxyethyl cellulose, mannan, galactomannan, xyloglucan, arabinoxylan, arabinan, xylan, and pectin. PaCel6A had a catalytic efficiency on cellotetraose comparable to that of Trichoderma reesei Cel6A (TrCel6A), but PaCel6B and PaCel6C were clearly less efficient. PaCel6A was the enzyme with the highest stability at 45°C, while PaCel6C was the least stable enzyme, losing more than 50% of its activity after incubation at temperatures above 30°C for 24 h. In contrast to TrCel6A, all three studied P. anserina GH6 cellulases were stable over a wide range of pHs and conserved high activity at pH values of up to 9. Each enzyme displayed a distinct substrate and product profile, highlighting different modes of action, with PaCel6A being the enzyme most similar to TrCel6A. PaCel6B was the only enzyme with higher specific activity on carboxymethylcellulose (CMC) than on Avicel and showed lower processivity than the others. Structural modeling predicts an open catalytic cleft, suggesting that PaCel6B is an endoglucanase.
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21
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Thongekkaew J, Ikeda H, Masaki K, Iefuji H. Fusion of cellulose binding domain from Trichoderma reesei CBHI to Cryptococcus sp. S-2 cellulase enhances its binding affinity and its cellulolytic activity to insoluble cellulosic substrates. Enzyme Microb Technol 2013; 52:241-6. [DOI: 10.1016/j.enzmictec.2013.02.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 02/04/2013] [Accepted: 02/04/2013] [Indexed: 11/24/2022]
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22
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Wu I, Arnold FH. Engineered thermostable fungal Cel6A and Cel7A cellobiohydrolases hydrolyze cellulose efficiently at elevated temperatures. Biotechnol Bioeng 2013; 110:1874-83. [PMID: 23404363 DOI: 10.1002/bit.24864] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 01/21/2013] [Accepted: 01/28/2013] [Indexed: 11/05/2022]
Abstract
Thermostability is an important feature in industrial enzymes: it increases biocatalyst lifetime and enables reactions at higher temperatures, where faster rates and other advantages ultimately reduce the cost of biocatalysis. Here we report the thermostabilization of a chimeric fungal family 6 cellobiohydrolase (HJPlus) by directed evolution using random mutagenesis and recombination of beneficial mutations. Thermostable variant 3C6P has a half-life of 280 min at 75°C and a T(50) of 80.1°C, a ~15°C increase over the thermostable Cel6A from Humicola insolens (HiCel6A) and a ~20°C increase over that from Hypocrea jecorina (HjCel6A). Most of the mutations also stabilize the less-stable HjCel6A, the wild-type Cel6A closest in sequence to 3C6P. During a 60-h Avicel hydrolysis, 3C6P released 2.4 times more cellobiose equivalents at its optimum temperature (T(opt)) of 75°C than HiCel6A at its T(opt) of 60°C. The total cellobiose equivalents released by HiCel6A at 60°C after 60 h is equivalent to the total released by 3C6P at 75°C after ~6 h, a 10-fold reduction in hydrolysis time. A binary mixture of thermostable Cel6A and Cel7A hydrolyzes Avicel synergistically and released 1.8 times more cellobiose equivalents than the wild-type mixture, both mixtures assessed at their respective T(opt). Crystal structures of HJPlus and 3C6P, determined at 1.5 and 1.2 Å resolution, indicate that the stabilization comes from improved hydrophobic interactions and restricted loop conformations by introduced proline residues.
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Affiliation(s)
- Indira Wu
- Division of Chemistry and Chemical Engineering, California Institute of Technology 210-41, Pasadena, CA 91125, USA
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23
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Li M, Tu M, Cao D, Bass P, Adhikari S. Distinct roles of residual xylan and lignin in limiting enzymatic hydrolysis of organosolv pretreated loblolly pine and sweetgum. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:646-54. [PMID: 23270516 DOI: 10.1021/jf304517w] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The interactions between xylan/lignin and cellulase enzymes play a key role in the effective hydrolysis of lignocellulosic biomass. Organosolv pretreated loblolly pine (OPLP) and sweetgum (OPSG) were used to quantitatively elucidate the distinct roles of residual xylan and lignin on enzymatic hydrolysis, based on the initial hydrolysis rates and the final hydrolysis yields. The initial hydrolysis rates of OPLP and OPSG were 1.45 (glucose) and 1.19 g/L/h (glucose), respectively, under the enzyme loading of 20 FPU/g glucan. The final glucan hydrolysis yields of OPLP and OPSG at 72 h were 76.4 and 98.9%, respectively. By correlating the amount of residual lignin and xylan to the initial hydrolysis rate and the final hydrolysis yield in OPLP and OPSG, a more accurate fundamental understanding of the roles of xylan and lignin in limiting the enzymatic hydrolysis has been developed. The higher amount of residual xylan (9.7%) in OPSG resulted in lower initial hydrolysis rate (1.19 g/L/h). The higher amount of residual lignin in OPLP (18.6%) resulted in lower final hydrolysis yield of glucan (76.4%). In addition, we observed in the simultaneous saccharification and fermentation (SSF) that ethyl xyloside was produced by the enzymatic catalysis of xylose/xylan and ethanol.
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Affiliation(s)
- Mi Li
- Forest Products Laboratory and Center for Bioenergy and Bioproducts, Auburn University, Auburn, Alabama 36849, United States
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24
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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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25
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Zhang J, Viikari L. Xylo-oligosaccharides are competitive inhibitors of cellobiohydrolase I from Thermoascus aurantiacus. BIORESOURCE TECHNOLOGY 2012; 117:286-91. [PMID: 22613900 DOI: 10.1016/j.biortech.2012.04.072] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 04/19/2012] [Accepted: 04/20/2012] [Indexed: 05/18/2023]
Abstract
The effects of xylo-oligosaccharides (XOS) and xylose on the hydrolytic activities of cellulases, endoglucanase II (EGII, originating from Thermoascus aurantiacus), cellobiohydrolase I (CBHI, from T. aurantiacus), and cellobiohydrolase II (CBHII, from Trichoderma reesei) on Avicel and nanocellulose were investigated. After the addition of XOS, the amounts of cellobiose, the main product released from Avicel and nanocellulose by CBHI, decreased from 0.78 and 1.37 mg/ml to 0.59 and 1.23 mg/ml, respectively. During hydrolysis by CBHII, the amounts of cellobiose released from the substrates were almost cut in half after the addition of XOS. Kinetic experiments showed that xylobiose and xylotriose were competitive inhibitors of CBHI. The results revealed that the strong inhibition of cellulase by XOS can be attributed to the inhibitory effect of XOS especially on cellobiohydrolase I. The results indicate the necessity to totally hydrolyze xylo-oligosaccharides into the less inhibitory product, xylose, to increasing hydrolytic efficiency.
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Affiliation(s)
- Junhua Zhang
- College of Forestry, Northwest A&F University, 3 Taicheng Road, Yangling 712100, China.
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26
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Jalak J, Kurašin M, Teugjas H, Väljamäe P. Endo-exo synergism in cellulose hydrolysis revisited. J Biol Chem 2012; 287:28802-15. [PMID: 22733813 DOI: 10.1074/jbc.m112.381624] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Synergistic cooperation of different enzymes is a prerequisite for efficient degradation of cellulose. The conventional mechanistic interpretation of the synergism between randomly acting endoglucanases (EGs) and chain end-specific processive cellobiohydrolases (CBHs) is that EG-generated new chain ends on cellulose surface serve as starting points for CBHs. Here we studied the hydrolysis of bacterial cellulose (BC) by CBH TrCel7A and EG TrCel5A from Trichoderma reesei under both single-turnover and "steady state" conditions. Unaccountable by conventional interpretation, the presence of EG increased the rate constant of TrCel7A-catalyzed hydrolysis of BC in steady state. At optimal enzyme/substrate ratios, the "steady state" rate of synergistic hydrolysis became limited by the velocity of processive movement of TrCel7A on BC. A processivity value of 66 ± 7 cellobiose units measured for TrCel7A on (14)C-labeled BC was close to the leveling off degree of polymerization of BC, suggesting that TrCel7A cannot pass through the amorphous regions on BC and stalls. We propose a mechanism of endo-exo synergism whereby the degradation of amorphous regions by EG avoids the stalling of TrCel7A and leads to its accelerated recruitment. Hydrolysis of pretreated wheat straw suggested that this mechanism of synergism is operative also in the degradation of lignocellulose. Although both mechanisms of synergism are used in parallel, the contribution of conventional mechanism is significant only at high enzyme/substrate ratios.
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Affiliation(s)
- Jürgen Jalak
- Institute of Molecular and Cell Biology, University of Tartu, Vanemuise 46-138, 51014 Tartu, Estonia
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27
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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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28
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Billard H, Faraj A, Lopes Ferreira N, Menir S, Heiss-Blanquet S. Optimization of a synthetic mixture composed of major Trichoderma reesei enzymes for the hydrolysis of steam-exploded wheat straw. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:9. [PMID: 22373423 PMCID: PMC3310832 DOI: 10.1186/1754-6834-5-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 02/28/2012] [Indexed: 05/03/2023]
Abstract
BACKGROUND An efficient hydrolysis of lignocellulosic substrates to soluble sugars for biofuel production necessitates the interplay and synergistic interaction of multiple enzymes. An optimized enzyme mixture is crucial for reduced cost of the enzymatic hydrolysis step in a bioethanol production process and its composition will depend on the substrate and type of pretreatment used. In the present study, an experimental design was used to determine the optimal composition of a Trichoderma reesei enzyme mixture, comprising the main cellulase and hemicellulase activities, for the hydrolysis of steam-exploded wheat straw. METHODS Six enzymes, CBH1 (Cel7a), CBH2 (Cel6a), EG1 (Cel7b), EG2 (Cel5a), as well as the xyloglucanase Cel74a and the xylanase XYN1 (Xyl11a) were purified from a T. reesei culture under lactose/xylose-induced conditions. Sugar release was followed in milliliter-scale hydrolysis assays for 48 hours and the influence of the mixture on initial conversion rates and final yields is assessed. RESULTS The developed model could show that both responses were strongly correlated. Model predictions suggest that optimal hydrolysis yields can be obtained over a wide range of CBH1 to CBH2 ratios, but necessitates a high proportion of EG1 (13% to 25%) which cannot be replaced by EG2. Whereas 5% to 10% of the latter enzyme and a xylanase content above 6% are required for highest yields, these enzymes are predicted to be less important in the initial stage of hydrolysis. CONCLUSIONS The developed model could reliably predict hydrolysis yields of enzyme mixtures in the studied domain and highlighted the importance of the respective enzyme components in both the initial and the final hydrolysis phase of steam-exploded wheat straw.
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Affiliation(s)
- Hélène Billard
- IFP Energies nouvelles, Biotechnology Department, 1 et 4 Avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France
| | - Abdelaziz Faraj
- IFP Energies nouvelles, Applied Mathematics Department, 1 et 4 Avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France
| | - Nicolas Lopes Ferreira
- IFP Energies nouvelles, Biotechnology Department, 1 et 4 Avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France
| | - Sandra Menir
- IFP Energies nouvelles, Biotechnology Department, 1 et 4 Avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France
| | - Senta Heiss-Blanquet
- IFP Energies nouvelles, Biotechnology Department, 1 et 4 Avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France
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Adav SS, Chao LT, Sze SK. Quantitative secretomic analysis of Trichoderma reesei strains reveals enzymatic composition for lignocellulosic biomass degradation. Mol Cell Proteomics 2012; 11:M111.012419. [PMID: 22355001 DOI: 10.1074/mcp.m111.012419] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Trichoderma reesei is a mesophilic, filamentous fungus, and it is a major industrial source of cellulases, but its lignocellulolytic protein expressions on lignocellulosic biomass are poorly explored at present. The extracellular proteins secreted by T. reesei QM6a wild-type and hypercellulolytic mutant Rut C30 grown on natural lignocellulosic biomasses were explored using a quantitative proteomic approach with 8-plex high throughput isobaric tags for relative and absolute quantification (iTRAQ) and analyzed by liquid chromatography tandem mass spectrometry. We quantified 230 extracellular proteins, including cellulases, hemicellulases, lignin-degrading enzymes, proteases, protein-translocating transporter, and hypothetical proteins. Quantitative iTRAQ results suggested that the expressions and regulations of these lignocellulolytic proteins in the secretome of T. reesei wild-type and mutant Rut C30 were dependent on both nature and complexity of different lignocellulosic carbon sources. Therefore, we discuss here the essential lignocellulolytic proteins for designing an enzyme mixture for optimal lignocellulosic biomass hydrolysis.
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Affiliation(s)
- Sunil S Adav
- School of Biological Sciences, Nanyang Technological University, Singapore
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30
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Hasunuma T, Kondo A. Development of yeast cell factories for consolidated bioprocessing of lignocellulose to bioethanol through cell surface engineering. Biotechnol Adv 2011; 30:1207-18. [PMID: 22085593 DOI: 10.1016/j.biotechadv.2011.10.011] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 10/12/2011] [Accepted: 10/30/2011] [Indexed: 10/15/2022]
Abstract
To build an energy and material secure future, a next generation of renewable fuels produced from lignocellulosic biomass is required. Although lignocellulosic biomass, which represents an abundant, inexpensive and renewable source for bioethanol production, is of great interest as a feedstock, the complicated ethanol production processes involved make the cost of producing bioethanol from it higher compared to corn starch and cane juice. Therefore, consolidated bioprocessing (CBP), which combines enzyme production, saccharification and fermentation in a single step, has gained increased recognition as a potential bioethanol production system. CBP requires a highly engineered microorganism developed for several different process-specific characteristics. The dominant strategy for engineering a CBP biocatalyst is to express multiple components of a cellulolytic system from either fungi or bacteria in the yeast Saccharomyces cerevisiae. The development of recombinant yeast strains displaying cellulases and hemicellulases on the cell surface represents significant progress toward realization of CBP. Regardless of the process used for biomass hydrolysis, CBP-enabling microorganisms encounter a variety of toxic compounds produced during biomass pretreatment that inhibit microbial growth and ethanol yield. Systems biology approaches including disruptome screening, transcriptomics, and metabolomics have been recently exploited to gain insight into the molecular and genetic traits involved in tolerance and adaptation to the fermentation inhibitors. In this review, we focus on recent advances in development of yeast strains with both the ability to directly convert lignocellulosic material to ethanol and tolerance in the harsh environments containing toxic compounds in the presence of ethanol.
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Affiliation(s)
- Tomohisa Hasunuma
- Organization of Advanced Science and Technology, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
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31
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Tambor JH, Ren H, Ushinsky S, Zheng Y, Riemens A, St-Francois C, Tsang A, Powlowski J, Storms R. Recombinant expression, activity screening and functional characterization identifies three novel endo-1,4-β-glucanases that efficiently hydrolyse cellulosic substrates. Appl Microbiol Biotechnol 2011; 93:203-14. [DOI: 10.1007/s00253-011-3419-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 05/24/2011] [Accepted: 05/28/2011] [Indexed: 11/27/2022]
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32
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Heiss-Blanquet S, Zheng D, Lopes Ferreira N, Lapierre C, Baumberger S. Effect of pretreatment and enzymatic hydrolysis of wheat straw on cell wall composition, hydrophobicity and cellulase adsorption. BIORESOURCE TECHNOLOGY 2011; 102:5938-46. [PMID: 21450460 DOI: 10.1016/j.biortech.2011.03.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 03/03/2011] [Accepted: 03/03/2011] [Indexed: 05/11/2023]
Abstract
The present study aimed to determine the impact of cell wall composition and lignin content on enzyme adsorption and degradability. Thioacidolysis analysis of residual lignins in wheat straw after steam-explosion or organosolv pretreatment revealed an increase in lignin condensation degree of 27% and 33%, respectively. Surface hydrophobicity assessed through wettability tests decreased after the pretreatments (contact angle decrease of 20-50%), but increased with enzymatic conversion (30% maximum contact angle increase) and correlatively to lignin content. Adsorption of the three major cellulases Cel7A, Cel6A and Cel7B from Trichoderma reesei decreased with increasing hydrolysis time, down to 7%, 31% and 70% on the sample with the highest lignin content, respectively. The fraction of unspecifically bound enzymes was dependent both on the enzyme and the lignin content. Adsorption and specific activity were shown to be inversely proportional to lignin content and hydrophobicity, suggesting that lignin is one of the factors restricting enzymatic hydrolysis.
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Affiliation(s)
- Senta Heiss-Blanquet
- IFP Energies nouvelles, 1 et 4, avenue de Bois-Préau, 92852 Rueil-Malmaison, France.
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Gao D, Chundawat SP, Uppugundla N, Balan V, Dale BE. Binding characteristics of Trichoderma reesei cellulases on untreated, ammonia fiber expansion (AFEX), and dilute-acid pretreated lignocellulosic biomass. Biotechnol Bioeng 2011; 108:1788-800. [DOI: 10.1002/bit.23140] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 03/01/2011] [Accepted: 03/07/2011] [Indexed: 11/10/2022]
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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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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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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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Hall M, Bansal P, Lee JH, Realff MJ, Bommarius AS. Cellulose crystallinity - a key predictor of the enzymatic hydrolysis rate. FEBS J 2010; 277:1571-82. [DOI: 10.1111/j.1742-4658.2010.07585.x] [Citation(s) in RCA: 408] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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38
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Bansal P, Hall M, Realff MJ, Lee JH, Bommarius AS. Modeling cellulase kinetics on lignocellulosic substrates. Biotechnol Adv 2009; 27:833-848. [DOI: 10.1016/j.biotechadv.2009.06.005] [Citation(s) in RCA: 302] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 06/19/2009] [Accepted: 06/20/2009] [Indexed: 11/15/2022]
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Hu G, Heitmann JA, Rojas OJ. In Situ Monitoring of Cellulase Activity by Microgravimetry with a Quartz Crystal Microbalance. J Phys Chem B 2009; 113:14761-8. [DOI: 10.1021/jp907155v] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gang Hu
- Department of Forest Biomaterials, North Carolina State University, Campus Box 8005, Raleigh North Carolina 27695-8005, and Department of Forest Products Technology, Faculty of Chemistry and Materials Sciences, Helsinki University of Technology, P.O. Box 3320, FIN-02015 TKK, Espoo, Finland
| | - John A. Heitmann
- Department of Forest Biomaterials, North Carolina State University, Campus Box 8005, Raleigh North Carolina 27695-8005, and Department of Forest Products Technology, Faculty of Chemistry and Materials Sciences, Helsinki University of Technology, P.O. Box 3320, FIN-02015 TKK, Espoo, Finland
| | - Orlando J. Rojas
- Department of Forest Biomaterials, North Carolina State University, Campus Box 8005, Raleigh North Carolina 27695-8005, and Department of Forest Products Technology, Faculty of Chemistry and Materials Sciences, Helsinki University of Technology, P.O. Box 3320, FIN-02015 TKK, Espoo, Finland
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40
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YIN SD, TAO XX, SHI KY. Bio-solubilization of Chinese lignite II: protein adsorption onto the lignite surface. ACTA ACUST UNITED AC 2009. [DOI: 10.1016/s1674-5264(09)60068-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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41
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Kim ES, Lee HJ, Bang WG, Choi IG, Kim KH. Functional characterization of a bacterial expansin from Bacillus subtilis for enhanced enzymatic hydrolysis of cellulose. Biotechnol Bioeng 2009; 102:1342-53. [PMID: 19058186 DOI: 10.1002/bit.22193] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Expansin is a plant protein family that induces plant cell wall-loosening and cellulose disruption without exerting cellulose-hydrolytic activity. Expansin-like proteins have also been found in other eukaryotes such as nematodes and fungi. While searching for an expansin produced by bacteria, we found that the BsEXLX1 protein from Bacillus subtilis had a structure that was similar to that of a beta-expansin produced by maize. Therefore, we cloned the BsEXLX1 gene and expressed it in Escherichia coli to evaluate its function. When incubated with filter paper as a cellulose substrate, the recombinant protein exhibited both cellulose-binding and cellulose-weakening activities, which are known functions of plant expansins. In addition, evaluation of the enzymatic hydrolysis of filter paper revealed that the recombinant protein also displayed a significant synergism when mixed with cellulase. By comparing the activity of a mixture of cellulase and the bacterial expansin to the additive activity of the individual proteins, the synergistic activity was found to be as high as 240% when filter paper was incubated with cellulase and BsEXLX1, which was 5.7-fold greater than the activity of cellulase alone. However, this synergistic effect was observed when only a low dosage of cellulase was used. This is the first study to characterize the function of an expansin produced by a non-eukaryotic source.
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Affiliation(s)
- Eun Sil Kim
- School of Life Sciences & Biotechnology, Korea University, Seoul 136-713, Republic of Korea
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42
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Fukuda H, Kondo A, Tamalampudi S. Bioenergy: Sustainable fuels from biomass by yeast and fungal whole-cell biocatalysts. Biochem Eng J 2009. [DOI: 10.1016/j.bej.2008.11.016] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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43
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Kim KH, Brown KM, Harris PV, Langston JA, Cherry JR. A Proteomics Strategy To Discover β-Glucosidases from Aspergillus fumigatus with Two-Dimensional Page In-Gel Activity Assay and Tandem Mass Spectrometry. J Proteome Res 2007; 6:4749-57. [DOI: 10.1021/pr070355i] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Kee-Hong Kim
- Novozymes, Inc., 1445 Drew Avenue, Davis California 95618
| | | | - Paul V. Harris
- Novozymes, Inc., 1445 Drew Avenue, Davis California 95618
| | | | - Joel R. Cherry
- Novozymes, Inc., 1445 Drew Avenue, Davis California 95618
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44
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Gusakov AV, Salanovich TN, Antonov AI, Ustinov BB, Okunev ON, Burlingame R, Emalfarb M, Baez M, Sinitsyn AP. Design of highly efficient cellulase mixtures for enzymatic hydrolysis of cellulose. Biotechnol Bioeng 2007; 97:1028-38. [PMID: 17221887 DOI: 10.1002/bit.21329] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
An extremely highly active cellobiohydrolase (CBH IIb or Cel6B) was isolated from Chrysosporium lucknowense UV18-25 culture filtrate. The CBH IIb demonstrated the highest ability for a deep degradation of crystalline cellulose amongst a few cellobiohydrolases tested, including C. lucknowense CBH Ia, Ib, IIa, and Trichoderma reesei CBH I and II. Using purified C. lucknowense enzymes (CBH Ia, Ib, and IIb; endoglucanases II and V; beta-glucosidase, xylanase II), artificial multienzyme mixtures were reconstituted, displaying an extremely high performance in a conversion of different cellulosic substrates (Avicel, cotton, pretreated Douglas fir wood) to glucose. These mixtures were much or notably more effective in hydrolysis of the cellulosic substrates than the crude multienzyme C. lucknowense preparation and other crude cellulase samples produced by T. reesei and Penicillium verruculosum. Highly active cellulases are a key factor in bioconversion of plant lignocellulosic biomass to ethanol as an alternative to fossil fuels.
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Affiliation(s)
- Alexander V Gusakov
- Department of Chemistry, M. V. Lomonosov Moscow State University, Moscow 119899, Russia.
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45
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Viikari L, Alapuranen M, Puranen T, Vehmaanperä J, Siika-Aho M. Thermostable enzymes in lignocellulose hydrolysis. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2007; 108:121-45. [PMID: 17589813 DOI: 10.1007/10_2007_065] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Thermostable enzymes offer potential benefits in the hydrolysis of lignocellulosic substrates; higher specific activity decreasing the amount of enzymes, enhanced stability allowing improved hydrolysis performance and increased flexibility with respect to process configurations, all leading to improvement of the overall economy of the process. New thermostable cellulase mixtures were composed of cloned fungal enzymes for hydrolysis experiments. Three thermostable cellulases, identified as the most promising enzymes in their categories (cellobiohydrolase, endoglucanase and beta-glucosidase), were cloned and produced in Trichoderma reesei and mixed to compose a novel mixture of thermostable cellulases. Thermostable xylanase was added to enzyme preparations used on substrates containing residual hemicellulose. The new optimised thermostable enzyme mixtures were evaluated in high temperature hydrolysis experiments on technical steam pretreated raw materials: spruce and corn stover. The hydrolysis temperature could be increased by about 10-15 degrees C, as compared with present commercial Trichoderma enzymes. The same degree of hydrolysis, about 90% of theoretical, measured as individual sugars, could be obtained with the thermostable enzymes at 60 degrees C as with the commercial enzymes at 45 degrees C. Clearly more efficient hydrolysis per assayed FPU unit or per amount of cellobiohydrolase I protein used was obtained. The maximum FPU activity of the novel enzyme mixture was about 25% higher at the optimum temperature at 65 degrees C, as compared with the highest activity of the commercial reference enzyme at 60 degrees C. The results provide a promising basis to produce and formulate improved enzyme products. These products can have high temperature stability in process conditions in the range of 55-60 degrees C (with present industrial products at 45-50 degrees C) and clearly improved specific activity, essentially decreasing the protein dosage required for an efficient hydrolysis of lignocellulosic substrates. New types of process configurations based on thermostable enzymes are discussed.
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Affiliation(s)
- Liisa Viikari
- University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland.
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46
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Tomaz CT, Rocha AS, Queiroz JA. Hydrophobic interaction chromatography ofTrichoderma reeseicellulases on polypropylene glycol–sepharose. SEP SCI TECHNOL 2007. [DOI: 10.1081/ss-120002741] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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47
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Wang L, Zhang Y, Gao P, Shi D, Liu H, Gao H. Changes in the structural properties and rate of hydrolysis of cotton fibers during extended enzymatic hydrolysis. Biotechnol Bioeng 2006; 93:443-56. [PMID: 16196052 DOI: 10.1002/bit.20730] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An extended enzymatic hydrolysis of cotton fibers by crude cellulase from Trichoderma pseudokoningii S-38 is described with characterization of both the enzyme changes of activities and cellulose structure. The hydrolysis rates declined drastically during the early stage and then slowly and steadily throughout the whole hydrolysis process the same trend could be seen during the following re-hydrolysis process. Morphological and structural changes to the fibers, such as swelling, frequent surface erosion, and variation in the packing and orientation of microfibrils, were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Observation of X-ray diffraction and IR spectra suggests that the hydrolysis process results in a gradual increase in the relative intensity of the hydrogen bond network, and a gradual decrease in the apparent crystal size of cellulose. The I(alpha) crystal phase was hydrolyzed more easily than was the I(beta) crystal phase. Apart from the inactivation of CBHs activity, changes in the packing and arrangement of microfibrils and the structural heterogeneity of cellulose during hydrolysis could be responsible for the reduction in the rate of reaction, especially in its later stages. The results indicate that the enzymatic hydrolysis of cellulose occurs on the outer layer of the fiber surface and that, following this, the process continues in a sub-layer manner.
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Affiliation(s)
- Lushan Wang
- Key Laboratory of Microbiology, Shandong University, Jinan, China
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48
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Phalip V, Delalande F, Carapito C, Goubet F, Hatsch D, Leize-Wagner E, Dupree P, Dorsselaer AV, Jeltsch JM. Diversity of the exoproteome of Fusarium graminearum grown on plant cell wall. Curr Genet 2005; 48:366-79. [PMID: 16283313 DOI: 10.1007/s00294-005-0040-3] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Revised: 10/25/2005] [Accepted: 10/25/2005] [Indexed: 11/30/2022]
Abstract
The exoproteome of the fungus Fusarium graminearum grown on glucose and on hop (Humulus lupulus, L.) cell wall has been investigated. The culture medium was found to contain a higher quantity of proteins and the proteins are more diverse when the fungus is grown on cell wall. Using both 1D and 2D electrophoresis followed by mass spectrometry analysis and protein identification based on similarity searches, 84 unique proteins were identified in the cell wall-grown fungal exoproteome. Many are putatively implicated in carbohydrate metabolism, mainly in cell wall polysaccharide degradation. The predicted carbohydrate-active enzymes fell into 24 different enzymes classes, and up to eight different proteins within a same class are secreted. This indicates that fungal metabolism becomes oriented towards synthesis and secretion of a whole arsenal of enzymes able to digest almost the complete plant cell wall. Cellobiohydrolase is one of the only four proteins found both after growth on glucose and on plant cell wall and we propose that this enzyme could act as a sensor of the extracellular environment. Extensive knowledge of this very diverse F. graminearum exoproteome is an important step towards the full understanding of Fusarium/plants interactions.
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Affiliation(s)
- Vincent Phalip
- UMR 7175-Laboratoire de Phytopathologie, Université Louis Pasteur, Illkirch, France.
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49
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Zhang YHP, Lynd LR. Toward an aggregated understanding of enzymatic hydrolysis of cellulose: noncomplexed cellulase systems. Biotechnol Bioeng 2005; 88:797-824. [PMID: 15538721 DOI: 10.1002/bit.20282] [Citation(s) in RCA: 883] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Information pertaining to enzymatic hydrolysis of cellulose by noncomplexed cellulase enzyme systems is reviewed with a particular emphasis on development of aggregated understanding incorporating substrate features in addition to concentration and multiple cellulase components. Topics considered include properties of cellulose, adsorption, cellulose hydrolysis, and quantitative models. A classification scheme is proposed for quantitative models for enzymatic hydrolysis of cellulose based on the number of solubilizing activities and substrate state variables included. We suggest that it is timely to revisit and reinvigorate functional modeling of cellulose hydrolysis, and that this would be highly beneficial if not necessary in order to bring to bear the large volume of information available on cellulase components on the primary applications that motivate interest in the subject.
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50
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Purification, cloning and characterisation of two forms of thermostable and highly active cellobiohydrolase I (Cel7A) produced by the industrial strain of Chrysosporium lucknowense. Enzyme Microb Technol 2005. [DOI: 10.1016/j.enzmictec.2004.03.025] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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