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Diethard M, Gasser B, Egermeier M, Marx H, Sauer M. Industrial Microorganisms: Saccharomyces cerevisiaeand other Yeasts. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1002/9783527807796.ch18] [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] Open
Affiliation(s)
- Mattanovich Diethard
- BOKU - University of Natural Resources and Life Sciences; Department of Biotechnology; Muthgasse 18 1190 Vienna Austria
- Austrian Centre of Industrial Biotechnology (ACIB GmbH); Muthgasse 18 1190 Vienna Austria
| | - Brigitte Gasser
- BOKU - University of Natural Resources and Life Sciences; Department of Biotechnology; Muthgasse 18 1190 Vienna Austria
- Austrian Centre of Industrial Biotechnology (ACIB GmbH); Muthgasse 18 1190 Vienna Austria
| | - Michael Egermeier
- BOKU - University of Natural Resources and Life Sciences; Department of Biotechnology; Muthgasse 18 1190 Vienna Austria
- BOKU - University of Natural Resources and Life Sciences; CD-Laboratory for Biotechnology of Glycerol; Muthgasse 18 1190 Vienna Austria
| | - Hans Marx
- BOKU - University of Natural Resources and Life Sciences; Department of Biotechnology; Muthgasse 18 1190 Vienna Austria
| | - Michael Sauer
- BOKU - University of Natural Resources and Life Sciences; Department of Biotechnology; Muthgasse 18 1190 Vienna Austria
- Austrian Centre of Industrial Biotechnology (ACIB GmbH); Muthgasse 18 1190 Vienna Austria
- BOKU - University of Natural Resources and Life Sciences; CD-Laboratory for Biotechnology of Glycerol; Muthgasse 18 1190 Vienna Austria
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Liu Z, Ho SH, Hasunuma T, Chang JS, Ren NQ, Kondo A. Recent advances in yeast cell-surface display technologies for waste biorefineries. BIORESOURCE TECHNOLOGY 2016; 215:324-333. [PMID: 27039354 DOI: 10.1016/j.biortech.2016.03.132] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 03/23/2016] [Accepted: 03/24/2016] [Indexed: 06/05/2023]
Abstract
Waste biorefinery aims to maximize the output of value-added products from various artificial/agricultural wastes by using integrated bioprocesses. To make waste biorefinery economically feasible, it is thus necessary to develop a low-cost, environment-friendly technique to perform simultaneous biodegradation and bioconversion of waste materials. Cell-surface display engineering is a novel, cost-effective technique that can auto-immobilize proteins on the cell exterior of microorganisms, and has been applied for use with waste biofinery. Through tethering different enzymes (e.g., cellulase, lipase, and protease) or metal-binding peptides on cell surfaces, various yeast strains can effectively produce biofuels and biochemicals from sugar/protein-rich waste materials, catalyze waste oils into biodiesels, or retrieve heavy metals from wastewater. This review critically summarizes recent applications of yeast cell-surface display on various types of waste biorefineries, highlighting its potential and future challenges with regard to commercializing this technology.
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Affiliation(s)
- Zhuo Liu
- Department of Chemical Science and Engineering, Kobe University, Kobe, Japan
| | - Shih-Hsin Ho
- State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute Technology, Harbin, PR China.
| | - Tomohisa Hasunuma
- Organization of Advanced Science and Technology, Kobe University, Kobe, Japan
| | - Jo-Shu Chang
- Department of Chemical Engineering, National Cheng Kung University, Taiwan; Research Center for Energy Technology and Strategy, National Cheng Kung University, Taiwan
| | - Nan-Qi Ren
- State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute Technology, Harbin, PR China
| | - Akihiko Kondo
- Department of Chemical Science and Engineering, Kobe University, Kobe, Japan
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53
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Heterologous expression of cellulase genes in natural Saccharomyces cerevisiae strains. Appl Microbiol Biotechnol 2016; 100:8241-54. [PMID: 27470141 DOI: 10.1007/s00253-016-7735-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/29/2016] [Accepted: 07/08/2016] [Indexed: 12/17/2022]
Abstract
Enzyme cost is a major impediment to second-generation (2G) cellulosic ethanol production. One strategy to reduce enzyme cost is to engineer enzyme production capacity in a fermentative microorganism to enable consolidated bio-processing (CBP). Ideally, a strain with a high secretory phenotype, high fermentative capacity as well as an innate robustness to bioethanol-specific stressors, including tolerance to products formed during pre-treatment and fermentation of lignocellulosic substrates should be used. Saccharomyces cerevisiae is a robust fermentative yeast but has limitations as a potential CBP host, such as low heterologous protein secretion titers. In this study, we evaluated natural S. cerevisiae isolate strains for superior secretion activity and other industrially relevant characteristics needed during the process of lignocellulosic ethanol production. Individual cellulases namely Saccharomycopsis fibuligera Cel3A (β-glucosidase), Talaromyces emersonii Cel7A (cellobiohydrolase), and Trichoderma reesei Cel5A (endoglucanase) were utilized as reporter proteins. Natural strain YI13 was identified to have a high secretory phenotype, demonstrating a 3.7- and 3.5-fold higher Cel7A and Cel5A activity, respectively, compared to the reference strain S288c. YI13 also demonstrated other industrially relevant characteristics such as growth vigor, high ethanol titer, multi-tolerance to high temperatures (37 and 40 °C), ethanol (10 % w/v), and towards various concentrations of a cocktail of inhibitory compounds commonly found in lignocellulose hydrolysates. This study accentuates the value of natural S. cerevisiae isolate strains to serve as potential robust and highly productive chassis organisms for CBP strain development.
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54
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Bischof RH, Ramoni J, Seiboth B. Cellulases and beyond: the first 70 years of the enzyme producer Trichoderma reesei. Microb Cell Fact 2016; 15:106. [PMID: 27287427 PMCID: PMC4902900 DOI: 10.1186/s12934-016-0507-6] [Citation(s) in RCA: 280] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/01/2016] [Indexed: 11/10/2022] Open
Abstract
More than 70 years ago, the filamentous ascomycete Trichoderma reesei was isolated on the Solomon Islands due to its ability to degrade and thrive on cellulose containing fabrics. This trait that relies on its secreted cellulases is nowadays exploited by several industries. Most prominently in biorefineries which use T. reesei enzymes to saccharify lignocellulose from renewable plant biomass in order to produce biobased fuels and chemicals. In this review we summarize important milestones of the development of T. reesei as the leading production host for biorefinery enzymes, and discuss emerging trends in strain engineering. Trichoderma reesei has very recently also been proposed as a consolidated bioprocessing organism capable of direct conversion of biopolymeric substrates to desired products. We therefore cover this topic by reviewing novel approaches in metabolic engineering of T. reesei.
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Affiliation(s)
- Robert H Bischof
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria
| | - Jonas Ramoni
- Molecular Biotechnology, Research Area Biochemical Technology, Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria
| | - Bernhard Seiboth
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria. .,Molecular Biotechnology, Research Area Biochemical Technology, Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria.
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55
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Liu Z, Ho SH, Sasaki K, den Haan R, Inokuma K, Ogino C, van Zyl WH, Hasunuma T, Kondo A. Engineering of a novel cellulose-adherent cellulolytic Saccharomyces cerevisiae for cellulosic biofuel production. Sci Rep 2016; 6:24550. [PMID: 27079382 PMCID: PMC4832201 DOI: 10.1038/srep24550] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/26/2016] [Indexed: 11/09/2022] Open
Abstract
Cellulosic biofuel is the subject of increasing attention. The main obstacle toward its economic feasibility is the recalcitrance of lignocellulose requiring large amount of enzyme to break. Several engineered yeast strains have been developed with cellulolytic activities to reduce the need for enzyme addition, but exhibiting limited effect. Here, we report the successful engineering of a cellulose-adherent Saccharomyces cerevisiae displaying four different synergistic cellulases on the cell surface. The cellulase-displaying yeast strain exhibited clear cell-to-cellulose adhesion and a "tearing" cellulose degradation pattern; the adhesion ability correlated with enhanced surface area and roughness of the target cellulose fibers, resulting in higher hydrolysis efficiency. The engineered yeast directly produced ethanol from rice straw despite a more than 40% decrease in the required enzyme dosage for high-density fermentation. Thus, improved cell-to-cellulose interactions provided a novel strategy for increasing cellulose hydrolysis, suggesting a mechanism for promoting the feasibility of cellulosic biofuel production.
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Affiliation(s)
- Zhuo Liu
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Shih-Hsin Ho
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.,State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, PR China
| | - Kengo Sasaki
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Riaan den Haan
- Department of Biotechnology, University of the Western Cape, Bellville 7530, South Africa
| | - Kentaro Inokuma
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Chiaki Ogino
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Willem H van Zyl
- Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa
| | - Tomohisa Hasunuma
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Akihiko Kondo
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.,Biomass Engineering Program, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
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56
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Vijayaraghavan P, Arun A, Al-Dhabi NA, Vincent SGP, Arasu MV, Choi KC. Novel Bacillus subtilis IND19 cell factory for the simultaneous production of carboxy methyl cellulase and protease using cow dung substrate in solid-substrate fermentation. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:73. [PMID: 27011767 PMCID: PMC4804545 DOI: 10.1186/s13068-016-0481-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/03/2016] [Indexed: 05/22/2023]
Abstract
BACKGROUND Hydrolytic enzymes, such as cellulases and proteases, have various applications, including bioethanol production, extraction of fruit and vegetable juice, detergent formulation, and leather processing. Solid-substrate fermentation has been an emerging method to utilize low-cost agricultural residues for the production of these enzymes. Although the production of carboxy methyl cellulase (CMCase) and protease in solid state fermentation (SSF) have been studied extensively, research investigating multienzyme production in a single fermentation process is limited. The production of multienzymes from a single fermentation system could reduce the overall production cost of enzymes. In order to achieve enhanced production of enzymes, the response surface methodology (RSM) was applied. RESULTS Bacillus subtilis IND19 utilized cow dung substrates for the production of CMCase and protease. A central composite design and a RSM were used to determine the optimal concentrations of peptone, NaH2PO4, and medium pH. Maximum productions of CMCase and protease were observed at 0.9 % peptone, 0.78 % NaH2PO4, and medium pH of 8.41, and 1 % peptone, 0.72 % NaH2PO4, and medium pH of 8.11, respectively. Under the optimized conditions, the experimental yield of CMCase and protease reached 473.01 and 4643 U/g, which were notably close to the predicted response (485.05 and 4710 U/g). These findings corresponded to an overall increase of 2.1- and 2.5-fold in CMCase and protease productions, respectively. CONCLUSIONS Utilization of cow dung for the production of enzymes is critical to producing multienzymes in a single fermentation step. Cow dung is available in large quantity throughout the year. This report is the first to describe simultaneous production of CMCase and protease using cow dung. This substrate could be directly used as the culture medium without any pretreatment for the production of these enzymes at an industrial scale.
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Affiliation(s)
- Ponnuswamy Vijayaraghavan
- />International Centre for Nanobiotechnology, Centre for Marine Science and Technology, Manonmaniam Sundaranar University, Rajakkamangalam, Kanyakumari, Tamil Nadu 629502 India
| | - Arumugaperumal Arun
- />Department of Biotechnology, Kalasalingam University, Srivilliputtur, Virudhunagar, Tamilnadu 626126 India
| | - Naif Abdullah Al-Dhabi
- />Department of Botany and Microbiology, Addiriyah Chair for Environmental Studies, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451 Saudi Arabia
| | - Samuel Gnana Prakash Vincent
- />International Centre for Nanobiotechnology, Centre for Marine Science and Technology, Manonmaniam Sundaranar University, Rajakkamangalam, Kanyakumari, Tamil Nadu 629502 India
| | - Mariadhas Valan Arasu
- />Department of Botany and Microbiology, Addiriyah Chair for Environmental Studies, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451 Saudi Arabia
| | - Ki Choon Choi
- />Grassland and forage division, National Institute of Animal Science, RDA, Seonghwan-Eup, Cheonan-Si, Chungnam 330-801 Republic of Korea
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57
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Gomes E, de Souza AR, Orjuela GL, Da Silva R, de Oliveira TB, Rodrigues A. Applications and Benefits of Thermophilic Microorganisms and Their Enzymes for Industrial Biotechnology. Fungal Biol 2016. [DOI: 10.1007/978-3-319-27951-0_21] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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58
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Ito Y, Yamanishi M, Ikeuchi A, Imamura C, Matsuyama T. Combinatorial Screening for Transgenic Yeasts with High Cellulase Activities in Combination with a Tunable Expression System. PLoS One 2015; 10:e0144870. [PMID: 26692026 PMCID: PMC4687128 DOI: 10.1371/journal.pone.0144870] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 11/24/2015] [Indexed: 01/26/2023] Open
Abstract
Combinatorial screening used together with a broad library of gene expression cassettes is expected to produce a powerful tool for the optimization of the simultaneous expression of multiple enzymes. Recently, we proposed a highly tunable protein expression system that utilized multiple genome-integrated target genes to fine-tune enzyme expression in yeast cells. This tunable system included a library of expression cassettes each composed of three gene-expression control elements that in different combinations produced a wide range of protein expression levels. In this study, four gene expression cassettes with graded protein expression levels were applied to the expression of three cellulases: cellobiohydrolase 1, cellobiohydrolase 2, and endoglucanase 2. After combinatorial screening for transgenic yeasts simultaneously secreting these three cellulases, we obtained strains with higher cellulase expressions than a strain harboring three cellulase-expression constructs within one high-performance gene expression cassette. These results show that our method will be of broad use throughout the field of metabolic engineering.
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Affiliation(s)
- Yoichiro Ito
- Matsuyama Research Group, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
- * E-mail: (TM); (YI)
| | - Mamoru Yamanishi
- Matsuyama Research Group, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
| | - Akinori Ikeuchi
- Biotechnology Laboratory, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
| | - Chie Imamura
- Biotechnology Laboratory, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
| | - Takashi Matsuyama
- Matsuyama Research Group, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
- * E-mail: (TM); (YI)
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59
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Mhlongo SI, den Haan R, Viljoen-Bloom M, van Zyl WH. Lignocellulosic hydrolysate inhibitors selectively inhibit/deactivate cellulase performance. Enzyme Microb Technol 2015; 81:16-22. [DOI: 10.1016/j.enzmictec.2015.07.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/01/2015] [Accepted: 07/23/2015] [Indexed: 12/01/2022]
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60
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Montenegro-Montero A, Goity A, Larrondo LF. The bZIP Transcription Factor HAC-1 Is Involved in the Unfolded Protein Response and Is Necessary for Growth on Cellulose in Neurospora crassa. PLoS One 2015; 10:e0131415. [PMID: 26132395 PMCID: PMC4488935 DOI: 10.1371/journal.pone.0131415] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 06/02/2015] [Indexed: 12/15/2022] Open
Abstract
High protein secretion capacity in filamentous fungi requires an extremely efficient system for protein synthesis, folding and transport. When the folding capacity of the endoplasmic reticulum (ER) is exceeded, a pathway known as the unfolded protein response (UPR) is triggered, allowing cells to mitigate and cope with this stress. In yeast, this pathway relies on the transcription factor Hac1, which mediates the up-regulation of several genes required under these stressful conditions. In this work, we identified and characterized the ortholog of the yeast HAC1 gene in the filamentous fungus Neurospora crassa. We show that its mRNA undergoes an ER stress-dependent splicing reaction, which in N. crassa removes a 23 nt intron and leads to a change in the open reading frame. By disrupting the N. crassa hac-1 gene, we determined it to be crucial for activating UPR and for proper growth in the presence of ER stress-inducing chemical agents. Neurospora is naturally found growing on dead plant material, composed primarily by lignocellulose, and is a model organism for the study of plant cell wall deconstruction. Notably, we found that growth on cellulose, a substrate that requires secretion of numerous enzymes, imposes major demands on ER function and is dramatically impaired in the absence of hac-1, thus broadening the range of physiological functions of the UPR in filamentous fungi. Growth on hemicellulose however, another carbon source that necessitates the secretion of various enzymes for its deconstruction, is not impaired in the mutant nor is the amount of proteins secreted on this substrate, suggesting that secretion, as a whole, is unaltered in the absence of hac-1. The characterization of this signaling pathway in N. crassa will help in the study of plant cell wall deconstruction by fungi and its manipulation may result in important industrial biotechnological applications.
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Affiliation(s)
- Alejandro Montenegro-Montero
- Millennium Nucleus for Fungal Integrative and Synthetic Biology, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alejandra Goity
- Millennium Nucleus for Fungal Integrative and Synthetic Biology, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Luis F. Larrondo
- Millennium Nucleus for Fungal Integrative and Synthetic Biology, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- * E-mail:
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61
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Tang H, Bao X, Shen Y, Song M, Wang S, Wang C, Hou J. Engineering protein folding and translocation improves heterologous protein secretion inSaccharomyces cerevisiae. Biotechnol Bioeng 2015; 112:1872-82. [DOI: 10.1002/bit.25596] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 03/11/2015] [Accepted: 03/16/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Hongting Tang
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 China
| | - Xiaoming Bao
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 China
| | - Yu Shen
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 China
| | - Meihui Song
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 China
| | - Shenghuan Wang
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 China
| | - Chengqiang Wang
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 China
| | - Jin Hou
- State Key Laboratory of Microbial Technology; Shandong University; Jinan 250100 China
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62
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Progress and challenges in the engineering of non-cellulolytic microorganisms for consolidated bioprocessing. Curr Opin Biotechnol 2015; 33:32-8. [DOI: 10.1016/j.copbio.2014.10.003] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 10/06/2014] [Accepted: 10/11/2014] [Indexed: 11/23/2022]
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Challenges for the production of bioethanol from biomass using recombinant yeasts. ADVANCES IN APPLIED MICROBIOLOGY 2015; 92:89-125. [PMID: 26003934 DOI: 10.1016/bs.aambs.2015.02.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Lignocellulose biomass, one of the most abundant renewable resources on the planet, is an alternative sustainable energy source for the production of second-generation biofuels. Energy in the form of simple or complex carbohydrates can be extracted from lignocellulose biomass and fermented by microorganisms to produce bioethanol. Despite 40 years of active and cutting-edge research invested into the development of technologies to produce bioethanol from lignocellulosic biomass, the process remains commercially unviable. This review describes the achievements that have been made in generating microorganisms capable of utilizing both simple and complex sugars from lignocellulose biomass and the fermentation of these sugars into ethanol. We also provide a discussion on the current "roadblocks" standing in the way of making second-generation bioethanol a commercially viable alternative to fossil fuels.
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64
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Linger JG, Taylor LE, Baker JO, Vander Wall T, Hobdey SE, Podkaminer K, Himmel ME, Decker SR. A constitutive expression system for glycosyl hydrolase family 7 cellobiohydrolases in Hypocrea jecorina. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:45. [PMID: 25904982 PMCID: PMC4405872 DOI: 10.1186/s13068-015-0230-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 02/23/2015] [Indexed: 05/23/2023]
Abstract
BACKGROUND One of the primary industrial-scale cellulase producers is the ascomycete fungus, Hypocrea jecorina, which produces and secretes large quantities of diverse cellulolytic enzymes. Perhaps the single most important biomass degrading enzyme is cellobiohydrolase I (cbh1or Cel7A) due to its enzymatic proficiency in cellulose depolymerization. However, production of Cel7A with native-like properties from heterologous expression systems has proven difficult. In this study, we develop a protein expression system in H. jecorina (Trichoderma reesei) useful for production and secretion of heterologous cellobiohydrolases from glycosyl hydrolase family 7. Building upon previous work in heterologous protein expression in filamentous fungi, we have integrated a native constitutive enolase promoter with the native cbh1 signal sequence. RESULTS The constitutive eno promoter driving the expression of Cel7A allows growth on glucose and results in repression of the native cellulase system, severely reducing background endo- and other cellulase activity and greatly simplifying purification of the recombinant protein. Coupling this system to a Δcbh1 strain of H. jecorina ensures that only the recombinant Cel7A protein is produced. Two distinct transformant colony morphologies were observed and correlated with high and null protein production. Production levels in 'fast' transformants are roughly equivalent to those in the native QM6a strain of H. jecorina, typically in the range of 10 to 30 mg/L when grown in continuous stirred-tank fermenters. 'Slow' transformants showed no evidence of Cel7A production. Specific activity of the purified recombinant Cel7A protein is equivalent to that of native protein when assayed on pretreated corn stover, as is the thermal stability and glycosylation level. Purified Cel7A produced from growth on glucose demonstrated remarkably consistent specific activity. Purified Cel7A from the same strain grown on lactose demonstrated significantly higher variability in activity. CONCLUSIONS The elimination of background cellulase induction provides much more consistent measured specific activity compared to a traditional cbh1 promoter system induced with lactose. This expression system provides a powerful tool for the expression and comparison of mutant and/or phylogenetically diverse cellobiohydrolases in the industrially relevant cellulase production host H. jecorina.
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Affiliation(s)
- Jeffrey G Linger
- />National Bioenergy Center, National Renewable Energy Laboratory, 16253 Denver West Parkway, Golden, CO 80401 USA
| | - Larry E Taylor
- />Biosciences Center, National Renewable Energy Laboratory, 16253 Denver West Parkway, Golden, CO 80401 USA
| | - John O Baker
- />Biosciences Center, National Renewable Energy Laboratory, 16253 Denver West Parkway, Golden, CO 80401 USA
| | - Todd Vander Wall
- />Biosciences Center, National Renewable Energy Laboratory, 16253 Denver West Parkway, Golden, CO 80401 USA
| | - Sarah E Hobdey
- />Biosciences Center, National Renewable Energy Laboratory, 16253 Denver West Parkway, Golden, CO 80401 USA
| | - Kara Podkaminer
- />Biosciences Center, National Renewable Energy Laboratory, 16253 Denver West Parkway, Golden, CO 80401 USA
| | - Michael E Himmel
- />Biosciences Center, National Renewable Energy Laboratory, 16253 Denver West Parkway, Golden, CO 80401 USA
| | - Stephen R Decker
- />Biosciences Center, National Renewable Energy Laboratory, 16253 Denver West Parkway, Golden, CO 80401 USA
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65
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Payne CM, Knott BC, Mayes HB, Hansson H, Himmel ME, Sandgren M, Ståhlberg J, Beckham GT. Fungal Cellulases. Chem Rev 2015; 115:1308-448. [DOI: 10.1021/cr500351c] [Citation(s) in RCA: 533] [Impact Index Per Article: 59.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Christina M. Payne
- Department
of Chemical and Materials Engineering and Center for Computational
Sciences, University of Kentucky, 177 F. Paul Anderson Tower, Lexington, Kentucky 40506, United States
| | - Brandon C. Knott
- National
Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
| | - Heather B. Mayes
- Department
of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Henrik Hansson
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Michael E. Himmel
- Biosciences
Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Mats Sandgren
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Jerry Ståhlberg
- Department
of Chemistry and Biotechnology, Swedish University of Agricultural Sciences, Uppsala BioCenter, Almas allé 5, SE-75651 Uppsala, Sweden
| | - Gregg T. Beckham
- National
Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver
West Parkway, Golden, Colorado 80401, United States
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66
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Ito Y, Yamanishi M, Ikeuchi A, Matsuyama T. A highly tunable system for the simultaneous expression of multiple enzymes in Saccharomyces cerevisiae. ACS Synth Biol 2015; 4:12-6. [PMID: 24927017 DOI: 10.1021/sb500096y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Control of the expression levels of multiple enzymes in transgenic yeasts is essential for the effective production of complex molecules through fermentation. Here, we propose a tunable strategy for the control of expression levels based on the design of terminator regions and other gene-expression control elements in Saccharomyces cerevisiae. Our genome-integrated system, which is capable of producing high expression levels over a wide dynamic range, will broadly enable metabolic engineering and synthetic biology. We demonstrated that the activities of multiple cellulases and the production of ethanol were doubled in a transgenic yeast constructed with our system compared with those achieved with a standard expression system.
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Affiliation(s)
- Yoichiro Ito
- Matsuyama Research Group and ‡Biotechnology Laboratory, Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan
| | - Mamoru Yamanishi
- Matsuyama Research Group and ‡Biotechnology Laboratory, Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan
| | - Akinori Ikeuchi
- Matsuyama Research Group and ‡Biotechnology Laboratory, Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan
| | - Takashi Matsuyama
- Matsuyama Research Group and ‡Biotechnology Laboratory, Toyota Central Research and Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan
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67
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Greene ER, Himmel ME, Beckham GT, Tan Z. Glycosylation of Cellulases: Engineering Better Enzymes for Biofuels. Adv Carbohydr Chem Biochem 2015; 72:63-112. [PMID: 26613815 DOI: 10.1016/bs.accb.2015.08.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Cellulose in plant cell walls is the largest reservoir of renewable carbon on Earth. The saccharification of cellulose from plant biomass into soluble sugars can be achieved using fungal and bacterial cellulolytic enzymes, cellulases, and further converted into fuels and chemicals. Most fungal cellulases are both N- and O-glycosylated in their native form, yet the consequences of glycosylation on activity and structure are not fully understood. Studying protein glycosylation is challenging as glycans are extremely heterogeneous, stereochemically complex, and glycosylation is not under direct genetic control. Despite these limitations, many studies have begun to unveil the role of cellulase glycosylation, especially in the industrially relevant cellobiohydrolase from Trichoderma reesei, Cel7A. Glycosylation confers many beneficial properties to cellulases including enhanced activity, thermal and proteolytic stability, and structural stabilization. However, glycosylation must be controlled carefully as such positive effects can be dampened or reversed. Encouragingly, methods for the manipulation of glycan structures have been recently reported that employ genetic tuning of glycan-active enzymes expressed from homogeneous and heterologous fungal hosts. Taken together, these studies have enabled new strategies for the exploitation of protein glycosylation for the production of enhanced cellulases for biofuel production.
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68
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Liu Z, Inokuma K, Ho SH, Haan RD, Hasunuma T, van Zyl WH, Kondo A. Combined cell-surface display- and secretion-based strategies for production of cellulosic ethanol with Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:162. [PMID: 26413161 PMCID: PMC4584016 DOI: 10.1186/s13068-015-0344-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/18/2015] [Indexed: 05/12/2023]
Abstract
BACKGROUND Engineering Saccharomyces cerevisiae to produce heterologous cellulases is considered as a promising strategy for production of bioethanol from lignocellulose. The production of cellulase is usually pursued by one of the two strategies: displaying enzyme on the cell surface or secreting enzyme into the medium. However, to our knowledge, the combination of the two strategies in a yeast strain has not been employed. RESULTS In this study, heterologous endoglucanase (EG) and cellobiohydrolase I (CBHI) were produced in a β-glucosidase displaying S. cerevisiae strain using cell-surface display, secretion, or a combined strategy. Strains EG-D-CBHI-D and EG-S-CBHI-S (with both enzymes displayed on the cell surface or with both enzymes secreted to the surrounding medium) showed higher ethanol production (2.9 and 2.6 g/L from 10 g/L phosphoric acid swollen cellulose, respectively), than strains EG-D-CBHI-S and EG-S-CBHI-D (with EG displayed on cell surface and CBHI secreted, or vice versa). After 3-cycle repeated-batch fermentation, the cellulose degradation ability of strain EG-D-CBHI-D remained 60 % of the 1st batch, at a level that was 1.7-fold higher than that of strain EG-S-CBHI-S. CONCLUSIONS This work demonstrated that placing EG and CBHI in the same space (on the cell surface or in the medium) was favorable for amorphous cellulose-based ethanol fermentation. In addition, the cellulolytic yeast strain that produced enzymes by the cell-surface display strategy performed better in cell-recycle batch fermentation compared to strains producing enzymes via the secretion strategy.
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Affiliation(s)
- Zhuo Liu
- />Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
| | - Kentaro Inokuma
- />Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
| | - Shih-Hsin Ho
- />Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
- />State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090 People’s Republic of China
| | - Riaan den Haan
- />Department of Biotechnology, University of the Western Cape, Bellville, 7530 South Africa
| | - Tomohisa Hasunuma
- />Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
| | - Willem H. van Zyl
- />Department of Microbiology, University of Stellenbosch, Stellenbosch, 7600 South Africa
| | - Akihiko Kondo
- />Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
- />Biomass Engineering Program, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045 Japan
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69
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Cavka A, Jo¨nsson LJ. Comparison of the growth of filamentous fungi and yeasts in lignocellulose-derived media. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2014. [DOI: 10.1016/j.bcab.2014.04.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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70
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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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71
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Moraïs S, Shterzer N, Lamed R, Bayer EA, Mizrahi I. A combined cell-consortium approach for lignocellulose degradation by specialized Lactobacillus plantarum cells. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:112. [PMID: 25788977 PMCID: PMC4364503 DOI: 10.1186/1754-6834-7-112] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 07/09/2014] [Indexed: 05/28/2023]
Abstract
BACKGROUND Lactobacillus plantarum is an attractive candidate for metabolic engineering towards bioprocessing of lignocellulosic biomass to ethanol or polylactic acid, as its natural characteristics include high ethanol and acid tolerance and the ability to metabolize the two major polysaccharide constituents of lignocellulolytic biomass (pentoses and hexoses). We recently engineered L. plantarum via separate introduction of a potent cellulase and xylanase, thereby creating two different L. plantarum strains. We used these strains as a combined cell-consortium for synergistic degradation of cellulosic biomass. RESULTS To optimize enzymatic degradation, we applied the cell-consortium approach to assess the significance of enzyme localization by comparing three enzymatic paradigms prevalent in nature: (i) a secreted enzymes system, (ii) enzymes anchored to the bacterial cell surface and (iii) enzymes integrated into cellulosome complexes. The construction of the three paradigmatic systems involved the division of the production and organization of the enzymes and scaffold proteins into different strains of L. plantarum. The spatial differentiation of the components of the enzymatic systems alleviated the load on the cell machinery of the different bacterial strains. Active designer cellulosomes containing a xylanase and a cellulase were thus assembled on L. plantarum cells by co-culturing three distinct engineered strains of the bacterium: two helper strains for enzyme secretion and one producing only the anchored scaffoldin. Alternatively, the two enzymes were anchored separately to the cell wall. The secreted enzyme consortium appeared to have a slight advantage over the designer cellulosome system in degrading the hypochlorite pretreated wheat straw substrate, and both exhibited significantly higher levels of activity compared to the anchored enzyme consortium. However, the secreted enzymes appeared to be less stable than the enzymes integrated into designer cellulosomes, suggesting an advantage of the latter over longer time periods. CONCLUSIONS By developing the potential of L. plantarum to express lignocellulolytic enzymes and to control their functional combination and stoichiometry on the cell wall, this study provides a step forward towards optimal biomass bioprocessing and soluble fermentable sugar production. Future expansion of the preferred secreted-enzyme and designer-cellulosome systems to include additional types of enzymes will promote enhanced deconstruction of cellulosic feedstocks.
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Affiliation(s)
- Sarah Moraïs
- />Department of Biological Chemistry, The Weizmann Institute of Science, 234 Herzl St, Rehovot, 7610001 Israel
| | - Naama Shterzer
- />Department of Ruminant Science, Institute of Animal Sciences, Agricultural Research Organization, P.O.B. 6, Bet-Dagan, 50250 Israel
| | - Raphael Lamed
- />Department of Molecular Microbiology and Biotechnology, Tel Aviv University, P.O. Box 39040, Ramat Aviv, 69978 Israel
| | - Edward A Bayer
- />Department of Biological Chemistry, The Weizmann Institute of Science, 234 Herzl St, Rehovot, 7610001 Israel
| | - Itzhak Mizrahi
- />Department of Ruminant Science, Institute of Animal Sciences, Agricultural Research Organization, P.O.B. 6, Bet-Dagan, 50250 Israel
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72
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Mitrovic A, Flicker K, Steinkellner G, Gruber K, Reisinger C, Schirrmacher G, Camattari A, Glieder A. Thermostability improvement of endoglucanase Cel7B from Hypocrea pseudokoningii. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.molcatb.2013.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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73
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Mir BA, Mewalal R, Mizrachi E, Myburg AA, Cowan DA. Recombinant hyperthermophilic enzyme expression in plants: a novel approach for lignocellulose digestion. Trends Biotechnol 2014; 32:281-9. [PMID: 24732021 DOI: 10.1016/j.tibtech.2014.03.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 02/14/2014] [Accepted: 03/05/2014] [Indexed: 10/25/2022]
Abstract
Plant biomass, as an abundant renewable carbon source, is a promising alternative to fossil fuels. However, the enzymes most commonly used for depolymerization of lignocellulosic biomass are expensive, and the development of cost-effective alternative conversion technologies would be desirable. One possible option is the heterologous expression of genes encoding lignocellulose-digesting enzymes in plant tissues. To overcome simultaneously issues of toxicity and incompatibility with high-temperature steam explosion processes, the use of heterologous genes encoding hyperthermophilic enzymes may be an attractive alternative. This approach could reduce the need for exogenous enzyme additions prior to fermentation, reducing the cost of the complete processing operation. This review highlights recent advances and future prospects for using hyperthermophilic enzymes in the biofuels industry.
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Affiliation(s)
- Bilal Ahmad Mir
- Center for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Private bag X20, Pretoria 0028, South Africa; Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private bag X20, Pretoria 0028, South Africa
| | - Ritesh Mewalal
- Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private bag X20, Pretoria 0028, South Africa
| | - Eshchar Mizrachi
- Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private bag X20, Pretoria 0028, South Africa
| | - Alexander A Myburg
- Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private bag X20, Pretoria 0028, South Africa
| | - Don A Cowan
- Center for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Private bag X20, Pretoria 0028, South Africa.
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74
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Biopharmaceutical protein production bySaccharomyces cerevisiae: current state and future prospects. ACTA ACUST UNITED AC 2014. [DOI: 10.4155/pbp.14.8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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75
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André I, Potocki-Véronèse G, Barbe S, Moulis C, Remaud-Siméon M. CAZyme discovery and design for sweet dreams. Curr Opin Chem Biol 2014; 19:17-24. [DOI: 10.1016/j.cbpa.2013.11.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 11/15/2013] [Accepted: 11/24/2013] [Indexed: 01/24/2023]
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76
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Fitzpatrick J, Kricka W, James TC, Bond U. Expression of three Trichoderma reesei cellulase genes in Saccharomyces pastorianus for the development of a two-step process of hydrolysis and fermentation of cellulose. J Appl Microbiol 2014; 117:96-108. [PMID: 24666670 DOI: 10.1111/jam.12494] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 02/26/2014] [Accepted: 03/04/2014] [Indexed: 11/26/2022]
Abstract
AIMS To compare the production of recombinant cellulase enzymes in two Saccharomyces species so as to ascertain the most suitable heterologous host for the degradation of cellulose-based biomass and its conversion into bioethanol. METHOD AND RESULTS cDNA copies of genes representing the three major classes of cellulases (Endoglucanases, Cellobiohydrolases and β-glucosidases) from Trichoderma reesei were expressed in Saccharomyces pastorianus and Saccharomyces cerevisiae. The recombinant enzymes were secreted by the yeast hosts into the medium and were shown to act in synergy to hydrolyse cellulose. The conditions required to achieve maximum release of glucose from cellulose by the recombinant enzymes were defined and the activity of the recombinant enzymes was compared to a commercial cocktail of T. reesei cellulases. CONCLUSIONS We demonstrate that significantly higher levels of cellulase activity were achieved by expression of the genes in S. pastorianus compared to S. cerevisiae. Hydrolysis of cellulose by the combined activity of the recombinant enzymes was significantly better at 50°C than at 30°C, the temperature used for mesophilic yeast fermentations, reflecting the known temperature profiles of the native enzymes. SIGNIFICANCE AND IMPACT OF THE STUDY The results demonstrate that host choice is important for the heterologous production of cellulases. On the basis of the low activity of the T. reesei recombinant enzymes at fermentation temperatures, we propose a two-step process for the hydrolysis of cellulose and its fermentation into alcohol using cellulases produced in situ.
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Affiliation(s)
- J Fitzpatrick
- School of Genetics and Microbiology, Moyne Institute, Trinity College Dublin, College Green, Dublin 2, Ireland
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77
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Over-expression of native Saccharomyces cerevisiae exocytic SNARE genes increased heterologous cellulase secretion. Appl Microbiol Biotechnol 2014; 98:5567-78. [DOI: 10.1007/s00253-014-5647-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Revised: 02/22/2014] [Accepted: 02/26/2014] [Indexed: 12/30/2022]
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78
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Kellermann SJ, Rentmeister A. Current Developments in Cellulase Engineering. CHEMBIOENG REVIEWS 2014. [DOI: 10.1002/cben.201300006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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79
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Dana CM, Dotson-Fagerstrom A, Roche CM, Kal SM, Chokhawala HA, Blanch HW, Clark DS. The importance of pyroglutamate in cellulase Cel7A. Biotechnol Bioeng 2014; 111:842-7. [PMID: 24375151 DOI: 10.1002/bit.25178] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 12/23/2013] [Accepted: 12/27/2013] [Indexed: 12/18/2022]
Abstract
The commercialization of lignocellulosic biofuels relies in part on the ability to engineer cellulase enzymes to have properties compatible with practical processing conditions. The cellulase Cel7A has been a common engineering target because it is present in very high concentrations in commercial cellulase cocktails. Significant effort has thus been focused on its recombinant expression. In particular, the yeast Saccharomyces cerevisiae has often been used both in the engineering and basic study of Cel7A. However, the expression titer and extent of glycosylation of Cel7A expressed in S. cerevisiae vary widely for Cel7A genes from different organisms, and the recombinant enzymes tend to be less active and less stable than their native counterparts. These observations motivate further study of recombinant expression of Cel7A in S. cerevisiae. Here, we compare the properties of Cel7A from Talaromyces emersonii expressed in both the budding yeast S. cerevisiae and the filamentous fungus Neurospora crassa. The Cel7A expressed in N. crassa had a higher melting temperature (by 10°C) and higher specific activity (twofold at 65°C) than the Cel7A expressed in S. cerevisiae. We examined several post-translational modifications and found that the underlying cause of this disparity was the lack of N-terminal glutamine cyclization in the Cel7A expressed in S. cerevisiae. Treating the enzyme in vitro with glutaminyl cyclase improved the properties of Cel7A expressed in S. cerevisiae to match those of Cel7A expressed in N. crassa.
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Affiliation(s)
- Craig M Dana
- Energy Biosciences Institute, University of California, Berkeley, 201 Calvin Laboratory, Berkeley, California, 94720; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, 491 Tan Hall, Berkeley, California, 94720
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80
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Wei H, Wang W, Alahuhta M, Vander Wall T, Baker JO, Taylor LE, Decker SR, Himmel ME, Zhang M. Engineering towards a complete heterologous cellulase secretome in Yarrowia lipolytica reveals its potential for consolidated bioprocessing. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:148. [PMID: 25337149 PMCID: PMC4203959 DOI: 10.1186/s13068-014-0148-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 09/24/2014] [Indexed: 05/03/2023]
Abstract
BACKGROUND Yarrowia lipolytica is an oleaginous yeast capable of metabolizing glucose to lipids, which then accumulate intracellularly. However, it lacks the suite of cellulolytic enzymes required to break down biomass cellulose and cannot therefore utilize biomass directly as a carbon source. Toward the development of a direct microbial conversion platform for the production of hydrocarbon fuels from cellulosic biomass, the potential for Y. lipolytica to function as a consolidated bioprocessing strain was investigated by first conducting a genomic search and functional testing of its endogenous glycoside hydrolases. Once the range of endogenous enzymes was determined, the critical cellulases from Trichoderma reesei were cloned into Yarrowia. RESULTS Initially, work to express T. reesei endoglucanase II (EGII) and cellobiohydrolase (CBH) II in Y. lipolytica resulted in the successful secretion of active enzymes. However, a critical cellulase, T. reesei CBHI, while successfully expressed in and secreted from Yarrowia, showed less than expected enzymatic activity, suggesting an incompatibility (probably at the post-translational level) for its expression in Yarrowia. This result prompted us to evaluate alternative or modified CBHI enzymes. Our subsequent expression of a T. reesei-Talaromyces emersonii (Tr-Te) chimeric CBHI, Chaetomium thermophilum CBHI, and Humicola grisea CBHI demonstrated remarkably improved enzymatic activities. Specifically, the purified chimeric Tr-Te CBHI showed a specific activity on Avicel that is comparable to that of the native T. reesei CBHI. Furthermore, the chimeric Tr-Te CBHI also showed significant synergism with EGII and CBHII in degrading cellulosic substrates, using either mixed supernatants or co-cultures of the corresponding Y. lipolytica transformants. The consortia system approach also allows rational volume mixing of the transformant cultures in accordance with the optimal ratio of cellulases required for efficient degradation of cellulosic substrates. CONCLUSIONS Taken together, this work demonstrates the first case of successful expression of a chimeric CBHI with essentially full native activity in Y. lipolytica, and supports the notion that Y. lipolytica strains can be genetically engineered, ultimately by heterologous expression of fungal cellulases and other enzymes, to directly convert lignocellulosic substrates to biofuels.
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Affiliation(s)
- Hui Wei
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Wei Wang
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Markus Alahuhta
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Todd Vander Wall
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - John O Baker
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Larry E Taylor
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Stephen R Decker
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Michael E Himmel
- />Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Min Zhang
- />National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
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81
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Xu L, Shen Y, Hou J, Peng B, Tang H, Bao X. Secretory pathway engineering enhances secretion of cellobiohydrolase I from Trichoderma reesei in Saccharomyces cerevisiae. J Biosci Bioeng 2014; 117:45-52. [DOI: 10.1016/j.jbiosc.2013.06.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 05/27/2013] [Accepted: 06/16/2013] [Indexed: 10/26/2022]
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82
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Lambertz C, Garvey M, Klinger J, Heesel D, Klose H, Fischer R, Commandeur U. Challenges and advances in the heterologous expression of cellulolytic enzymes: a review. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:135. [PMID: 25356086 PMCID: PMC4212100 DOI: 10.1186/s13068-014-0135-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/03/2014] [Indexed: 05/03/2023]
Abstract
Second generation biofuel development is increasingly reliant on the recombinant expression of cellulases. Designing or identifying successful expression systems is thus of preeminent importance to industrial progress in the field. Recombinant production of cellulases has been performed using a wide range of expression systems in bacteria, yeasts and plants. In a number of these systems, particularly when using bacteria and plants, significant challenges have been experienced in expressing full-length proteins or proteins at high yield. Further difficulties have been encountered in designing recombinant systems for surface-display of cellulases and for use in consolidated bioprocessing in bacteria and yeast. For establishing cellulase expression in plants, various strategies are utilized to overcome problems, such as the auto-hydrolysis of developing plant cell walls. In this review, we investigate the major challenges, as well as the major advances made to date in the recombinant expression of cellulases across the commonly used bacterial, plant and yeast systems. We review some of the critical aspects to be considered for industrial-scale cellulase production.
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Affiliation(s)
- Camilla Lambertz
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Megan Garvey
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- />Present address: School of Medicine, Deakin University, CSIRO Australian Animal Health Laboratory, 5 Portarlington Rd, Newcomb, VIC 3219 Australia
| | - Johannes Klinger
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Dirk Heesel
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Holger Klose
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- />Present address: Institute for Botany and Molecular Genetics, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
| | - Rainer Fischer
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- />Fraunhofer Institute for Molecular Biology and Applied Ecology, Forckenbeckstrasse 6, 52074 Aachen, Germany
| | - Ulrich Commandeur
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
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Boonvitthya N, Bozonnet S, Burapatana V, O'Donohue MJ, Chulalaksananukul W. Comparison of the heterologous expression of Trichoderma reesei endoglucanase II and cellobiohydrolase II in the yeasts Pichia pastoris and Yarrowia lipolytica. Mol Biotechnol 2013; 54:158-69. [PMID: 22638966 DOI: 10.1007/s12033-012-9557-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The sequences encoding the genes for endoglucanase II and cellobiohydrolase II from the fungus Trichoderma reesei QM9414 were successfully cloned and expressed in Yarrowia lipolytica under the control of the POX2 or TEF promoters, and using either the native or preproLip2 secretion signals. The expression level of both recombinant enzymes was compared with that obtained using Pichia pastoris, under the control of the AOX1 promoter to evaluate the utility of Y. lipolytica as a host strain for recombinant EGII and CBHII production. Extracellular endoglucanase activity was similar between TEF-preoproLip2-eglII expressed in Y. lipolytica and P. pastoris induced by 0.5 % (v/v) methanol, but when recombinant protein expression in P. pastoris was induced with 3 % (v/v) methanol, the activity was increased by about sevenfold. In contrast, the expression level of cellobiohydrolase from the TEF-preproLip2-cbhII cassette was higher in Y. lipolytica than in P. pastoris. Transformed Y. lipolytica produced up to 15 mg/l endoglucanase and 50 mg/l cellobiohydrolase, with the specific activity of both proteins being greater than their homologs produced by P. pastoris. Partial characterization of recombinant endoglucanase II and cellobiohydrolase II expressed in both yeasts revealed their optimum pH and temperature, and their pH and temperature stabilities were identical and hyperglycosylation had little effect on their enzymatic activity and properties.
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84
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Garvey M, Klose H, Fischer R, Lambertz C, Commandeur U. Cellulases for biomass degradation: comparing recombinant cellulase expression platforms. Trends Biotechnol 2013; 31:581-93. [DOI: 10.1016/j.tibtech.2013.06.006] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 06/21/2013] [Accepted: 06/24/2013] [Indexed: 10/26/2022]
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85
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Engineering chimeric thermostable GH7 cellobiohydrolases in Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2013; 98:2991-3001. [DOI: 10.1007/s00253-013-5177-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/29/2013] [Accepted: 07/30/2013] [Indexed: 10/26/2022]
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86
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Hughes SR, Bang SS, Cox EJ, Schoepke A, Ochwat K, Pinkelman R, Nelson D, Qureshi N, Gibbons WR, Kurtzman CP, Bischoff KM, Liu S, Cote GL, Rich JO, Jones MA, Cedeño D, Doran-Peterson J, Riaño-Herrera NM, Rodríguez-Valencia N, López-Núñez JC. Automated UV-C Mutagenesis of Kluyveromyces marxianus NRRL Y-1109 and Selection for Microaerophilic Growth and Ethanol Production at Elevated Temperature on Biomass Sugars. ACTA ACUST UNITED AC 2013; 18:276-90. [DOI: 10.1177/2211068213480037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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87
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Genome Sequences of Industrially Relevant Saccharomyces cerevisiae Strain M3707, Isolated from a Sample of Distillers Yeast and Four Haploid Derivatives. GENOME ANNOUNCEMENTS 2013; 1:1/3/e00323-13. [PMID: 23792743 PMCID: PMC3675515 DOI: 10.1128/genomea.00323-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Saccharomyces cerevisiae strain M3707 was isolated from a sample of commercial distillers yeast, and its genome sequence together with the genome sequences for the four derived haploid strains M3836, M3837, M3838, and M3839 has been determined. Yeasts have potential for consolidated bioprocessing (CBP) for biofuel production, and access to these genome sequences will facilitate their development.
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88
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Nielsen J, Larsson C, van Maris A, Pronk J. Metabolic engineering of yeast for production of fuels and chemicals. Curr Opin Biotechnol 2013; 24:398-404. [DOI: 10.1016/j.copbio.2013.03.023] [Citation(s) in RCA: 235] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 03/18/2013] [Accepted: 03/27/2013] [Indexed: 01/01/2023]
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89
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90
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Blifernez-Klassen O, Klassen V, Doebbe A, Kersting K, Grimm P, Wobbe L, Kruse O. Cellulose degradation and assimilation by the unicellular phototrophic eukaryote Chlamydomonas reinhardtii. Nat Commun 2013; 3:1214. [PMID: 23169055 DOI: 10.1038/ncomms2210] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 10/15/2012] [Indexed: 12/29/2022] Open
Abstract
Plants convert sunlight to biomass, which is primarily composed of lignocellulose, the most abundant natural biopolymer and a potential feedstock for fuel and chemical production. Cellulose assimilation has so far only been described for heterotrophic organisms that rely on photosynthetically active primary producers of organic compounds. Among phototrophs, the unicellular green microalga Chlamydomonas reinhardtii is widely known as one of the best established model organisms. It occupies many habitats, including aquatic and soil ecosystems. This ubiquity underscores the versatile metabolic properties of this microorganism. Here we present yet another paradigm of adaptation for C. reinhardtii, highlighting its photoheterotrophic ability to utilize cellulose for growth in the absence of other carbon sources. When grown under CO(2)-limiting conditions in the light, secretion of endo-β-1,4-glucanases by the cell causes digestion of exogenous cellulose, followed by cellobiose uptake and assimilation. Phototrophic microbes like C. reinhardtii may thus serve as biocatalysts for cellulosic biofuel production.
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Affiliation(s)
- Olga Blifernez-Klassen
- Department of Biology, Algae Biotechnology and Bioenergy-Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
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91
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Ethanol production from high cellulose concentration by the basidiomycete fungus Flammulina velutipes. Fungal Biol 2013; 117:220-6. [PMID: 23537879 DOI: 10.1016/j.funbio.2013.02.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 02/04/2013] [Accepted: 02/08/2013] [Indexed: 11/21/2022]
Abstract
Ethanol production by Flammulina velutipes from high substrate concentrations was evaluated. F. velutipes produces approximately 40-60 g l(-1) ethanol from 15% (w/v) D-glucose, D-fructose, D-mannose, sucrose, maltose, and cellobiose, with the highest conversion rate of 83% observed using cellobiose as a carbon source. We also attempted to assess direct ethanol fermentation from sugarcane bagasse cellulose (SCBC) by F. velutipes. The hydrolysis rate of 15% (w/v) SCBC with commercial cellulase was approximately 20%. In contrast, F. velutipes was able to produce a significant amount of ethanol from 15% SCBC with the production of β-glucosidase, cellobohydrolase, and cellulase, although the addition of a small amount of commercial cellulase to the culture was required for the conversion. When 9 mg g(-1) biomass of commercial cellulase was added to cultures, 0.36 g of ethanol was produced from 1 g of cellulose, corresponding to an ethanol conversion rate of 69.6%. These results indicate that F. velutipes would be useful for consolidated bioprocessing of lignocellulosic biomass to bioethanol.
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92
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Chang JJ, Ho FJ, Ho CY, Wu YC, Hou YH, Huang CC, Shih MC, Li WH. Assembling a cellulase cocktail and a cellodextrin transporter into a yeast host for CBP ethanol production. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:19. [PMID: 23374631 PMCID: PMC3599373 DOI: 10.1186/1754-6834-6-19] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 01/08/2013] [Indexed: 05/07/2023]
Abstract
BACKGROUND Many microorganisms possess enzymes that can efficiently degrade lignocellulosic materials, but do not have the capability to produce a large amount of ethanol. Thus, attempts have been made to transform such enzymes into fermentative microbes to serve as hosts for ethanol production. However, an efficient host for a consolidated bioprocess (CBP) remains to be found. For this purpose, a synthetic biology technique that can transform multiple genes into a genome is instrumental. Moreover, a strategy to select cellulases that interact synergistically is needed. RESULTS To engineer a yeast for CBP bio-ethanol production, a synthetic biology technique, called "promoter-based gene assembly and simultaneous overexpression" (PGASO), that can simultaneously transform and express multiple genes in a kefir yeast, Kluyveromyces marxianus KY3, was recently developed. To formulate an efficient cellulase cocktail, a filter-paper-activity assay for selecting heterologous cellulolytic enzymes was established in this study and used to select five cellulase genes, including two cellobiohydrolases, two endo-β-1,4-glucanases and one beta-glucosidase genes from different fungi. In addition, a fungal cellodextrin transporter gene was chosen to transport cellodextrin into the cytoplasm. These six genes plus a selection marker gene were one-step assembled into the KY3 genome using PGASO. Our experimental data showed that the recombinant strain KR7 could express the five heterologous cellulase genes and that KR7 could convert crystalline cellulose into ethanol. CONCLUSION Seven heterologous genes, including five cellulases, a cellodextrin transporter and a selection marker, were simultaneously transformed into the KY3 genome to derive a new strain, KR7, which could directly convert cellulose to ethanol. The present study demonstrates the potential of our strategy of combining a cocktail formulation protocol and a synthetic biology technique to develop a designer yeast host.
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Affiliation(s)
- Jui-Jen Chang
- Biodiversity Research Center, Academia Sinica, 115, Taipei, Taiwan
- Genomics Research Center, Academia Sinica, 115, Taipei, Taiwan
| | - Feng-Ju Ho
- Biodiversity Research Center, Academia Sinica, 115, Taipei, Taiwan
| | - Cheng-Yu Ho
- Department of Life Sciences, National Chung Hsing University, 402, Taichung, Taiwan
| | - Yueh-Chin Wu
- Biodiversity Research Center, Academia Sinica, 115, Taipei, Taiwan
| | - Yu-Han Hou
- Biodiversity Research Center, Academia Sinica, 115, Taipei, Taiwan
| | - Chieh-Chen Huang
- Department of Life Sciences, National Chung Hsing University, 402, Taichung, Taiwan
| | - Ming-Che Shih
- Agricultural Biotechnology Research, Center, Academia Sinica, 115, Taipei, Taiwan
| | - Wen-Hsiung Li
- Biodiversity Research Center, Academia Sinica, 115, Taipei, Taiwan
- Genomics Research Center, Academia Sinica, 115, Taipei, Taiwan
- Department of Ecology and Evolution, University of Chicago, 60637, Chicago, IL, USA
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93
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den Haan R, Kroukamp H, van Zyl JHD, van Zyl WH. Cellobiohydrolase secretion by yeast: Current state and prospects for improvement. Process Biochem 2013. [DOI: 10.1016/j.procbio.2012.11.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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94
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Mazzoli R. Development of microorganisms for cellulose-biofuel consolidated bioprocessings: metabolic engineers' tricks. Comput Struct Biotechnol J 2012; 3:e201210007. [PMID: 24688667 PMCID: PMC3962139 DOI: 10.5936/csbj.201210007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Revised: 10/22/2012] [Accepted: 10/24/2012] [Indexed: 01/04/2023] Open
Abstract
Cellulose waste biomass is the most abundant and attractive substrate for "biorefinery strategies" that are aimed to produce high-value products (e.g. solvents, fuels, building blocks) by economically and environmentally sustainable fermentation processes. However, cellulose is highly recalcitrant to biodegradation and its conversion by biotechnological strategies currently requires economically inefficient multistep industrial processes. The need for dedicated cellulase production continues to be a major constraint to cost-effective processing of cellulosic biomass. Research efforts have been aimed at developing recombinant microorganisms with suitable characteristics for single step biomass fermentation (consolidated bioprocessing, CBP). Two paradigms have been applied for such, so far unsuccessful, attempts: a) "native cellulolytic strategies", aimed at conferring high-value product properties to natural cellulolytic microorganisms; b) "recombinant cellulolytic strategies", aimed to confer cellulolytic ability to microorganisms exhibiting high product yields and titers. By starting from the description of natural enzyme systems for plant biomass degradation and natural metabolic pathways for some of the most valuable product (i.e. butanol, ethanol, and hydrogen) biosynthesis, this review describes state-of-the-art bottlenecks and solutions for the development of recombinant microbial strains for cellulosic biofuel CBP by metabolic engineering. Complexed cellulases (i.e. cellulosomes) benefit from stronger proximity effects and show enhanced synergy on insoluble substrates (i.e. crystalline cellulose) with respect to free enzymes. For this reason, special attention was held on strategies involving cellulosome/designer cellulosome-bearing recombinant microorganisms.
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Affiliation(s)
- Roberto Mazzoli
- Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, 10123 Torino, Italy
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95
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Komor RS, Romero PA, Xie CB, Arnold FH. Highly thermostable fungal cellobiohydrolase I (Cel7A) engineered using predictive methods. Protein Eng Des Sel 2012; 25:827-33. [PMID: 22961332 DOI: 10.1093/protein/gzs058] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Building on our previous efforts to generate thermostable chimeric fungal cellobiohydrolase I (CBH I, also known as Cel7A) cellulases by structure-guided recombination, we used FoldX and a 'consensus' sequence approach to identify individual mutations present in the five homologous parent CBH I enzymes which further stabilize the chimeras. Using the FoldX force field, we calculated the effect on ΔG(Folding) of each candidate mutation in a number of CBH I structures and chose those predicted to be stabilizing in multiple structures. With an alignment of 41 CBH I sequences, we also used amino acid frequencies at each candidate position to calculate predicted effects on ΔG(Folding). A combination of mutations chosen using these methods increased the T(50) of the most thermostable chimera by an additional 4.7°C, to yield a CBH I with T(50) of 72.1°C, which is 9.2°C higher than that of the most stable native CBH I, from Talaromyces emersonii. This increased stability resulted in a 10°C increase in the optimal temperature for activity, to 65°C, and a 50% increase in total sugar production from crystalline cellulose at the optimal temperature, compared with native T.emersonii CBH I.
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Affiliation(s)
- Russell S Komor
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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96
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Chang JJ, Ho CY, Ho FJ, Tsai TY, Ke HM, Wang CHT, Chen HL, Shih MC, Huang CC, Li WH. PGASO: A synthetic biology tool for engineering a cellulolytic yeast. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:53. [PMID: 22839502 PMCID: PMC3462719 DOI: 10.1186/1754-6834-5-53] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 06/28/2012] [Indexed: 05/07/2023]
Abstract
BACKGROUND To achieve an economical cellulosic ethanol production, a host that can do both cellulosic saccharification and ethanol fermentation is desirable. However, to engineer a non-cellulolytic yeast to be such a host requires synthetic biology techniques to transform multiple enzyme genes into its genome. RESULTS A technique, named Promoter-based Gene Assembly and Simultaneous Overexpression (PGASO), that employs overlapping oligonucleotides for recombinatorial assembly of gene cassettes with individual promoters, was developed. PGASO was applied to engineer Kluyveromycesmarxianus KY3, which is a thermo- and toxin-tolerant yeast. We obtained a recombinant strain, called KR5, that is capable of simultaneously expressing exoglucanase and endoglucanase (both of Trichodermareesei), a beta-glucosidase (from a cow rumen fungus), a neomycin phosphotransferase, and a green fluorescent protein. High transformation efficiency and accuracy were achieved as ~63% of the transformants was confirmed to be correct. KR5 can utilize beta-glycan, cellobiose or CMC as the sole carbon source for growth and can directly convert cellobiose and beta-glycan to ethanol. CONCLUSIONS This study provides the first example of multi-gene assembly in a single step in a yeast species other than Saccharomyces cerevisiae. We successfully engineered a yeast host with a five-gene cassette assembly and the new host is capable of co-expressing three types of cellulase genes. Our study shows that PGASO is an efficient tool for simultaneous expression of multiple enzymes in the kefir yeast KY3 and that KY3 can serve as a host for developing synthetic biology tools.
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Affiliation(s)
- Jui-Jen Chang
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Cheng-Yu Ho
- Department of Life Sciences, National Chung Hsing University, Taichung, 402, Taiwan
- Biotechnology Center, National Chung Hsing University, Taichung, 115, Taiwan
| | - Feng-Ju Ho
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Tsung-Yu Tsai
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Huei-Mien Ke
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
- Microbial Genomics, National Chung Hsing University, Taichung, 402, Taiwan
| | | | - Hsin-Liang Chen
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Ming-Che Shih
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 115, Taiwan
| | - Chieh-Chen Huang
- Department of Life Sciences, National Chung Hsing University, Taichung, 402, Taiwan
- Biotechnology Center, National Chung Hsing University, Taichung, 115, Taiwan
| | - Wen-Hsiung Li
- Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan
- Department of Ecology and Evolution, University of Chicago, Chicago, IL, 60637, USA
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97
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van Zyl WH, Bloom M, Viktor MJ. Engineering yeasts for raw starch conversion. Appl Microbiol Biotechnol 2012; 95:1377-88. [PMID: 22797599 DOI: 10.1007/s00253-012-4248-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 06/12/2012] [Accepted: 06/14/2012] [Indexed: 11/29/2022]
Abstract
Next to cellulose, starch is the most abundant hexose polymer in plants, an import food and feed source and a preferred substrate for the production of many industrial products. Efficient starch hydrolysis requires the activities of both α-1,4 and α-1,6-debranching hydrolases, such as endo-amylases, exo-amylases, debranching enzymes, and transferases. Although amylases are widely distributed in nature, only about 10 % of amylolytic enzymes are able to hydrolyse raw or unmodified starch, with a combination of α-amylases and glucoamylases as minimum requirement for the complete hydrolysis of raw starch. The cost-effective conversion of raw starch for the production of biofuels and other important by-products requires the expression of starch-hydrolysing enzymes in a fermenting yeast strain to achieve liquefaction, hydrolysis, and fermentation (Consolidated Bioprocessing, CBP) by a single organism. The status of engineering amylolytic activities into Saccharomyces cerevisiae as fermentative host is highlighted and progress as well as challenges towards a true CBP organism for raw starch is discussed. Conversion of raw starch by yeast secreting or displaying α-amylases and glucoamylases on their surface has been demonstrated, although not at high starch loading or conversion rates that will be economically viable on industrial scale. Once efficient conversion of raw starch can be demonstrated at commercial level, engineering of yeast to utilize alternative substrates and produce alternative chemicals as part of a sustainable biorefinery can be pursued to ensure the rightful place of starch converting yeasts in the envisaged bio-economy of the future.
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Affiliation(s)
- W H van Zyl
- Department of Microbiology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
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98
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Olson DG, McBride JE, Joe Shaw A, Lynd LR. Recent progress in consolidated bioprocessing. Curr Opin Biotechnol 2012; 23:396-405. [DOI: 10.1016/j.copbio.2011.11.026] [Citation(s) in RCA: 370] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 11/08/2011] [Accepted: 11/23/2011] [Indexed: 12/30/2022]
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99
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van Rensburg E, den Haan R, Smith J, van Zyl WH, Görgens JF. The metabolic burden of cellulase expression by recombinant Saccharomyces cerevisiae Y294 in aerobic batch culture. Appl Microbiol Biotechnol 2012; 96:197-209. [PMID: 22526794 DOI: 10.1007/s00253-012-4037-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 03/14/2012] [Accepted: 03/16/2012] [Indexed: 12/29/2022]
Abstract
Two recombinant strains of Saccharomyces cerevisiae Y294 producing cellulase using different expression strategies were compared to a reference strain in aerobic culture to evaluate the potential metabolic burden that cellulase expression imposed on the yeast metabolism. In a chemically defined mineral medium with glucose as carbon source, S. cerevisiae strain Y294[CEL5] with plasmid-borne cellulase genes produced endoglucanase and β-glucosidase activities of 0.038 and 0.30 U mg dry cell weight(-1), respectively. Chromosomal expression of these two cellulases in strain Y294[Y118p] resulted in no detectable activity, although low levels of episomally co-expressed cellobiohydrolase (CBH) activity were detected. Whereas the biomass concentration of strain Y294[CEL5] was slightly greater than that of a reference strain, CBH expression by Y294[Y118p] resulted in a 1.4-fold lower maximum specific growth rate than that of the reference. Supplementation of the growth medium with amino acids significantly improved culture growth and enzyme production, but only partially mitigated the physiological effects and metabolic burden of cellulase expression. Glycerol production was decreased significantly, up to threefold, in amino acid-supplemented cultures, apparently due to redox balancing. Disproportionately higher levels of glycerol production by Y294[CEL5] indicated a potential correlation between the redox balance of anabolism and the physiological stress of cellulase production. With the reliance on cellulase expression in yeast for the development of consolidated bioprocesses for bioethanol production, this work demonstrates the need for development of yeasts that are physiologically robust in response to burdens imposed by heterologous enzyme production.
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Affiliation(s)
- Eugéne van Rensburg
- Department of Process Engineering, Stellenbosch University, Private Bag X1, Stellenbosch, 7602, South Africa
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