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Duan Y, Ren W, Zhao J, Luo C, Liu Y. Planting Cyperus esculentus augments soil microbial biomass and diversity, but not enzymatic activities. PeerJ 2022; 10:e14199. [PMID: 36258793 PMCID: PMC9573350 DOI: 10.7717/peerj.14199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 09/16/2022] [Indexed: 01/24/2023] Open
Abstract
The planting of Cyperus esculentus, a member of the grass family Cyperaceae which includes nut sedge weeds, is being increasingly promoted in northern China's semi-arid and arid regions. Yet the effects of planting C. esculentus upon soil quality and soil microbial characteristics of sandy land remain unclear. This study examined the short-term (1 year) impact of this grass species on soil microbial biomass indices, enzymatic activities, and microbiome characteristics in the Horqin Sandy Land area of China. The results show that planting C. esculentus could increase microbial biomass in the form of carbon (MBC), nitrogen (MBN), and phosphorus (MBP), but it negligibly influenced the enzymatic activities of soil β-1,4-glucosidase (BG), cellobiohydrolase (CBH), leucine aminopeptidase (LAP), and β-1,4-N-acetaminoglycosidase (NAG). Over 1 year, we found that planting C. esculentus significantly increased the soil bacterial richness and diversity of sandy land, yet also altered community composition of soil bacteria and eukaryotes in way that could promote their homogenization. In this respect, the relative abundances of Acidobacteria and Proteobacteria significantly decreased and increased, respectively; hence, they may be considered for use as important indicators of soil nutrient-rich conditions. Overall, the results could be explained by greater soil organic carbon (SOC) and total nitrogen (TN), mainly derived from cumulative plant litter input to soils, which then increased the sandy soil's C:N ratio. Future research should focus on exploring the long-term effects of planting C. esculentus on soil quality and soil microbial characteristics of sandy lands in China and abroad.
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Affiliation(s)
- Yulong Duan
- Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu, China,Naiman Desertification Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Tongliao, China
| | - Wei Ren
- Agricultural Biotechnology Institute, Jilin Academy of Agricultural Sciences, Changchun, China
| | - Jianhua Zhao
- Shanghai Majorbio Bio-pharm Technology Co., Ltd, Shanghai, China
| | - Chun Luo
- Shanghai Majorbio Bio-pharm Technology Co., Ltd, Shanghai, China
| | - Yang Liu
- Gansu Institute of Architectural Design and Research Company, Lanzhou, Gansu, China
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2
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Chetty BJ, Inokuma K, Hasunuma T, van Zyl WH, den Haan R. Improvement of cell-tethered cellulase activity in recombinant strains of Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2022; 106:6347-6361. [PMID: 35951080 DOI: 10.1007/s00253-022-12114-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/27/2022] [Accepted: 07/28/2022] [Indexed: 11/30/2022]
Abstract
Consolidated bioprocessing (CBP) remains an attractive option for the production of commodity products from pretreated lignocellulose if a process-suitable organism can be engineered. The yeast Saccharomyces cerevisiae requires engineered cellulolytic activity to enable its use in CBP production of second-generation (2G) bioethanol. A promising strategy for heterologous cellulase production in yeast entails displaying enzymes on the cell surface by means of glycosylphosphatidylinositol (GPI) anchors. While strains producing a core set of cell-adhered cellulases that enabled crystalline cellulose hydrolysis have been created, secreted levels of enzyme were insufficient for complete cellulose hydrolysis. In fact, all reported recombinant yeast CBP candidates must overcome the drawback of generally low secretion titers. Rational strain engineering can be applied to enhance the secretion phenotype. This study aimed to improve the amount of cell-adhered cellulase activities of recombinant S. cerevisiae strains expressing a core set of four cellulases, through overexpression of genes that were previously shown to enhance cellulase secretion. Results showed significant increases in cellulolytic activity for all cell-adhered cellulase enzyme types. Cell-adhered cellobiohydrolase activity was improved by up to 101%, β-glucosidase activity by up to 99%, and endoglucanase activity by up to 231%. Improved hydrolysis of crystalline cellulose of up to 186% and improved ethanol yields from this substrate of 40-50% in different strain backgrounds were also observed. In addition, improvement in resistance to fermentation stressors was noted in some strains. These strains represent a step towards more efficient organisms for use in 2G biofuel production. KEY POINTS: • Cell-surface-adhered cellulase activity was improved in strains engineered for CBP. • Levels of improvement of activity were strain and enzyme dependent. • Crystalline cellulose conversion to ethanol could be improved up to 50%.
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Affiliation(s)
- Bronwyn Jean Chetty
- Department of Biotechnology, University of the Western Cape, Bellville, South Africa
| | - Kentaro Inokuma
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
| | - Tomohisa Hasunuma
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
| | | | - Riaan den Haan
- Department of Biotechnology, University of the Western Cape, Bellville, South Africa.
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3
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Alahuhta M, Xu Q, Knoshaug EP, Wang W, Wei H, Amore A, Baker JO, Vander Wall T, Himmel ME, Zhang M. Chimeric cellobiohydrolase I expression, activity, and biochemical properties in three oleaginous yeast. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:6. [PMID: 33407766 PMCID: PMC7789491 DOI: 10.1186/s13068-020-01856-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/10/2020] [Indexed: 05/16/2023]
Abstract
Consolidated bioprocessing using oleaginous yeast is a promising modality for the economic conversion of plant biomass to fuels and chemicals. However, yeast are not known to produce effective biomass degrading enzymes naturally and this trait is essential for efficient consolidated bioprocessing. We expressed a chimeric cellobiohydrolase I gene in three different oleaginous, industrially relevant yeast: Yarrowia lipolytica, Lipomyces starkeyi, and Saccharomyces cerevisiae to study the biochemical and catalytic properties and biomass deconstruction potential of these recombinant enzymes. Our results showed differences in glycosylation, surface charge, thermal and proteolytic stability, and efficacy of biomass digestion. L. starkeyi was shown to be an inferior active cellulase producer compared to both the Y. lipolytica and S. cerevisiae enzymes, whereas the cellulase expressed in S. cerevisiae displayed the lowest activity against dilute-acid-pretreated corn stover. Comparatively, the chimeric cellobiohydrolase I enzyme expressed in Y. lipolytica was found to have a lower extent of glycosylation, better protease stability, and higher activity against dilute-acid-pretreated corn stover.
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Affiliation(s)
- Markus Alahuhta
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA.
| | - Qi Xu
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Eric P Knoshaug
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Wei Wang
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Hui Wei
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Antonella Amore
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - John O Baker
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Todd Vander Wall
- 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
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA.
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4
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Ye M, Ye Y, Du Z, Chen G. Cell-surface engineering of yeasts for whole-cell biocatalysts. Bioprocess Biosyst Eng 2021; 44:1003-1019. [PMID: 33389168 DOI: 10.1007/s00449-020-02484-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/16/2020] [Indexed: 01/23/2023]
Abstract
Due to the unique advantages comparing with traditional free enzymes and chemical catalysis, whole-cell biocatalysts have been widely used to catalyze reactions effectively, simply and environment friendly. Cell-surface display technology provides a novel and effective approach for improved whole-cell biocatalysts expressing heterologous enzymes on the cell surface. They can overcome the substrate transport limitation of the intracellular expression and provide the enzymes with enhanced properties. Among all the host surface-displaying microorganisms, yeast is ideally suitable for constructing whole cell-surface-displaying biocatalyst, because of the large cell size, the generally regarded as safe (GRAS) status, and the perfect post-translational processing of secreted proteins. Yeast cell-surface display system has been a promising and powerful method for development of novel and improved engineered biocatalysts. In this review, the characterization and principles of yeast cell-surface display and the applications of yeast cell-surface display in engineered whole-cell biocatalysts as well as the improvement of the enzyme efficiency are summarized and discussed.
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Affiliation(s)
- Mengqi Ye
- Marine College, Shandong University, Weihai, 264209, China
| | - Yuqi Ye
- Marine College, Shandong University, Weihai, 264209, China
| | - Zongjun Du
- Marine College, Shandong University, Weihai, 264209, China
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China
| | - Guanjun Chen
- Marine College, Shandong University, Weihai, 264209, China.
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China.
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5
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Giovannoni M, Gramegna G, Benedetti M, Mattei B. Industrial Use of Cell Wall Degrading Enzymes: The Fine Line Between Production Strategy and Economic Feasibility. Front Bioeng Biotechnol 2020; 8:356. [PMID: 32411686 PMCID: PMC7200985 DOI: 10.3389/fbioe.2020.00356] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 03/31/2020] [Indexed: 12/14/2022] Open
Abstract
Cell Wall Degrading Enzymes (CWDEs) are a heterogeneous group of enzymes including glycosyl-hydrolases, oxidoreductases, lyases, and esterases. Microbes with degrading activities toward plant cell wall polysaccharides are the most relevant source of CWDEs for industrial applications. These organisms secrete a wide array of CWDEs in amounts strictly necessary for their own sustenance, nonetheless the production of CWDEs from wild type microbes can be increased at large-scale by using optimized fermentation strategies. In the last decades, advances in genetic engineering allowed the expression of recombinant CWDEs also in lab-domesticated organisms such as E. coli, yeasts and plants, dramatically increasing the available options for the large-scale production of CWDEs. The optimization of a CWDE-producing biofactory is a hard challenge that biotechnologists tackle by testing different expression strategies and expression-hosts. Although both the yield and production costs are critical factors to produce biomolecules at industrial scale, these parameters are often disregarded in basic research. This review presents the main characteristics and industrial applications of CWDEs directed toward the cell wall of plants, bacteria, fungi and microalgae. Different biofactories for CWDE expression are compared in order to highlight strengths and weaknesses of each production system and how these aspects impact the final enzyme cost and, consequently, the economic feasibility of using CWDEs for industrial applications.
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Affiliation(s)
- Moira Giovannoni
- Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy
| | - Giovanna Gramegna
- Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy
| | - Manuel Benedetti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy
| | - Benedetta Mattei
- Department of Life, Health and Environmental Sciences, University of L'Aquila, L'Aquila, Italy
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6
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Exploiting strain diversity and rational engineering strategies to enhance recombinant cellulase secretion by Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2020; 104:5163-5184. [PMID: 32337628 DOI: 10.1007/s00253-020-10602-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/26/2020] [Accepted: 03/31/2020] [Indexed: 12/14/2022]
Abstract
Consolidated bioprocessing (CBP) of lignocellulosic material into bioethanol has progressed in the past decades; however, several challenges still exist which impede the industrial application of this technology. Identifying the challenges that exist in all unit operations is crucial and needs to be optimised, but only the barriers related to the secretion of recombinant cellulolytic enzymes in Saccharomyces cerevisiae will be addressed in this review. Fundamental principles surrounding CBP as a biomass conversion platform have been established through the successful expression of core cellulolytic enzymes, namely β-glucosidases, endoglucanases, and exoglucanases (cellobiohydrolases) in S. cerevisiae. This review will briefly address the challenges involved in the construction of an efficient cellulolytic yeast, with particular focus on the secretion efficiency of cellulases from this host. Additionally, strategies for studying enhanced cellulolytic enzyme secretion, which include both rational and reverse engineering approaches, will be discussed. One such technique includes bio-engineering within genetically diverse strains, combining the strengths of both natural strain diversity and rational strain development. Furthermore, with the advancement in next-generation sequencing, studies that utilise this method of exploiting intra-strain diversity for industrially relevant traits will be reviewed. Finally, future prospects are discussed for the creation of ideal CBP strains with high enzyme production levels.Key Points• Several challenges are involved in the construction of efficient cellulolytic yeast, in particular, the secretion efficiency of cellulases from the hosts.• Strategies for enhancing cellulolytic enzyme secretion, a core requirement for CBP host microorganism development, include both rational and reverse engineering approaches.• One such technique includes bio-engineering within genetically diverse strains, combining the strengths of both natural strain diversity and rational strain development.
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7
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Cedras G, Kroukamp H, Van Zyl WH, Den Haan R. The
in vivo
detection and measurement of the unfolded protein response in recombinant cellulase producing
Saccharomyces cerevisiae
strains. Biotechnol Appl Biochem 2020; 67:82-94. [DOI: 10.1002/bab.1819] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 08/16/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Gillian Cedras
- Department of BiotechnologyUniversity of the Western Cape Bellville South Africa
| | - Heinrich Kroukamp
- Department of Molecular SciencesMacquarie University North Ryde NSW Australia
| | | | - Riaan Den Haan
- Department of BiotechnologyUniversity of the Western Cape Bellville South Africa
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8
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Green Production and Biotechnological Applications of Cell Wall Lytic Enzymes. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9235012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
: Energy demand is constantly growing, and, nowadays, fossil fuels still play a dominant role in global energy production, despite their negative effects on air pollution and the emission of greenhouse gases, which are the main contributors to global warming. An alternative clean source of energy is represented by the lignocellulose fraction of plant cell walls, the most abundant carbon source on Earth. To obtain biofuels, lignocellulose must be efficiently converted into fermentable sugars. In this regard, the exploitation of cell wall lytic enzymes (CWLEs) produced by lignocellulolytic fungi and bacteria may be considered as an eco-friendly alternative. These organisms evolved to produce a variety of highly specific CWLEs, even if in low amounts. For an industrial use, both the identification of novel CWLEs and the optimization of sustainable CWLE-expressing biofactories are crucial. In this review, we focus on recently reported advances in the heterologous expression of CWLEs from microbial and plant expression systems as well as some of their industrial applications, including the production of biofuels from agricultural feedstock and of value-added compounds from waste materials. Moreover, since heterologous expression of CWLEs may be toxic to plant hosts, genetic strategies aimed in converting such a deleterious effect into a beneficial trait are discussed.
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9
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Davison SA, den Haan R, van Zyl WH. Identification of superior cellulase secretion phenotypes in haploids derived from natural Saccharomyces cerevisiae isolates. FEMS Yeast Res 2019; 19:5154912. [PMID: 30388213 DOI: 10.1093/femsyr/foy117] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 10/31/2018] [Indexed: 01/11/2023] Open
Abstract
The yeast Saccharomyces cerevisiae is considered an important host for consolidated bioprocessing and the production of high titres of recombinant cellulases is required for efficient hydrolysis of lignocellulosic substrates to fermentable sugars. Since recombinant protein secretion profiles vary highly among different strain backgrounds, careful selection of robust strains with optimal secretion profiles is of crucial importance. Here, we construct and screen sets of haploid derivatives, derived from natural strain isolates YI13, FINI and YI59, for improved general cellulase secretion. This report details a novel approach that combines secretion profiles of strains and phenotypic responses to stresses known to influence the secretion pathway for the development of a phenotypic screen to isolate strains with improved secretory capacities. A clear distinction was observed between the YI13 haploid derivatives and industrial and laboratory counterparts, Ethanol Red and S288c, respectively. By using sub-lethal concentrations of the secretion stressor tunicamycin and cell wall stressor Congo Red, YI13 haploid derivative strains demonstrated tolerance profiles related to their heterologous secretion profiles. Our results demonstrated that a new screening technique combined with a targeted mating approach could produce a pool of novel strains capable of high cellulase secretion.
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Affiliation(s)
- Steffi A Davison
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - Riaan den Haan
- Department of Biotechnology, University of the Western Cape, Bellville 7535, South Africa
| | - Willem Heber van Zyl
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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10
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Song X, Li Y, Wu Y, Cai M, Liu Q, Gao K, Zhang X, Bai Y, Xu H, Qiao M. Metabolic engineering strategies for improvement of ethanol production in cellulolytic Saccharomyces cerevisiae. FEMS Yeast Res 2019; 18:5071949. [PMID: 30107496 DOI: 10.1093/femsyr/foy090] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 08/09/2018] [Indexed: 01/31/2023] Open
Abstract
As a traditional ethanol-producing microorganism, Saccharomyces cerevisiae is an ideal host for consolidated bioprocessing. However, expression of heterologous cellulase increases the metabolic burden in yeast, which results in low cellulase activity and poor cellulose degradation efficiency. In this study, cellulase-expressing yeast strains that could efficiently degrade different cellulosic substrates were created by optimizing cellulase ratios through a POT1-mediated δ-integration strategy. Metabolic engineering strategies, including optimization of codon usage, promoter and signal peptide, were also included in this system. We also confirmed that heterologous cellulase expression in cellulosic yeast induced the unfolded protein response. To enhance protein folding capacity, the endoplasmic reticulum chaperone protein BiP and the disulfide isomerase Pdi1p were overexpressed, and the Golgi membrane protein Ca2+/Mn2+ ATPase Pmr1p was disrupted to decrease the glycosylation of cellulase. The resultant strain, SK18-3, could produce 5.4 g L-1 ethanol with carboxymethyl-cellulose. Strain SK12-50 achieved 4.7 g L-1 ethanol production with phosphoric acid swollen cellulose hydrolysis. When Avicel was used as the substrate, 3.8 g L-1 ethanol (75% of the theoretical maximum yield) was produced in SK13-34. This work will significantly increase our knowledge of how to engineer optimal yeast strains for biofuel production from cellulosic biomass.
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Affiliation(s)
- Xiaofei Song
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Yuanzi Li
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Yuzhen Wu
- Department of Microbiology, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Miao Cai
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Quanli Liu
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Kai Gao
- Tianjin Academy of Environmental Sciences, No. 17 Fukang Road, Nankai District, Tianjin 300071, China
| | - Xiuming Zhang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Yanling Bai
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Haijin Xu
- Department of Microbiology, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
| | - Mingqiang Qiao
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin 300071, China
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11
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Wei H, Wang W, Alper HS, Xu Q, Knoshaug EP, Van Wychen S, Lin CY, Luo Y, Decker SR, Himmel ME, Zhang M. Ameliorating the Metabolic Burden of the Co-expression of Secreted Fungal Cellulases in a High Lipid-Accumulating Yarrowia lipolytica Strain by Medium C/N Ratio and a Chemical Chaperone. Front Microbiol 2019; 9:3276. [PMID: 30687267 PMCID: PMC6333634 DOI: 10.3389/fmicb.2018.03276] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 12/17/2018] [Indexed: 12/19/2022] Open
Abstract
Yarrowia lipolytica, known to accumulate lipids intracellularly, lacks the cellulolytic enzymes needed to break down solid biomass directly. This study aimed to evaluate the potential metabolic burden of expressing core cellulolytic enzymes in an engineered high lipid-accumulating strain of Y. lipolytica. Three fungal cellulases, Talaromyces emersonii-Trichoderma reesei chimeric cellobiohydrolase I (chimeric-CBH I), T. reesei cellobiohydrolase II (CBH II), and T. reesei endoglucanase II (EG II) were expressed using three constitutive strong promoters as a single integrative expression block in a recently engineered lipid hyper-accumulating strain of Y. lipolytica (HA1). In yeast extract-peptone-dextrose (YPD) medium, the resulting cellulase co-expressing transformant YL165-1 had the chimeric-CBH I, CBH II, and EG II secretion titers being 26, 17, and 132 mg L-1, respectively. Cellulase co-expression in YL165-1 in culture media with a moderate C/N ratio of ∼4.5 unexpectedly resulted in a nearly two-fold reduction in cellular lipid accumulation compared to the parental control strain, a sign of cellular metabolic drain. Such metabolic drain was ameliorated when grown in media with a high C/N ratio of 59 having a higher glucose utilization rate that led to approximately twofold more cell mass and threefold more lipid production per liter culture compared to parental control strain, suggesting cross-talk between cellulase and lipid production, both of which involve the endoplasmic reticulum (ER). Most importantly, we found that the chemical chaperone, trimethylamine N-oxide dihydride increased glucose utilization, cell mass and total lipid titer in the transformants, suggesting further amelioration of the metabolic drain. This is the first study examining lipid production in cellulase-expressing Y. lipolytica strains under various C/N ratio media and with a chemical chaperone highlighting the metabolic complexity for developing robust, cellulolytic and lipogenic yeast strains.
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Affiliation(s)
- Hui Wei
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Wei Wang
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Hal S Alper
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, United States
| | - Qi Xu
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Eric P Knoshaug
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Stefanie Van Wychen
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States.,National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Chien-Yuan Lin
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Yonghua Luo
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Stephen R Decker
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Michael E Himmel
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States
| | - Min Zhang
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, United States.,National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, United States
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12
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Xu Q, Alahuhta M, Wei H, Knoshaug EP, Wang W, Baker JO, Vander Wall T, Himmel ME, Zhang M. Expression of an endoglucanase-cellobiohydrolase fusion protein in Saccharomyces cerevisiae, Yarrowia lipolytica, and Lipomyces starkeyi. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:322. [PMID: 30524504 PMCID: PMC6278004 DOI: 10.1186/s13068-018-1301-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/25/2018] [Indexed: 05/28/2023]
Abstract
The low secretion levels of cellobiohydrolase I (CBHI) in yeasts are one of the key barriers preventing yeast from directly degrading and utilizing lignocellulose. To overcome this obstacle, we have explored the approach of genetically linking an easily secreted protein to CBHI, with CBHI being the last to be folded. The Trichoderma reesei eg2 (TrEGII) gene was selected as the leading gene due to its previously demonstrated outstanding secretion in yeast. To comprehensively characterize the effects of this fusion protein, we tested this hypothesis in three industrially relevant yeasts: Saccharomyces cerevisiae, Yarrowia lipolytica, and Lipomyces starkeyi. Our initial assays with the L. starkeyi secretome expressing differing TrEGII domains fused to a chimeric Talaromyces emersonii-T. reesei CBHI (TeTrCBHI) showed that the complete TrEGII enzyme, including the glycoside hydrolase (GH) 5 domain is required for increased expression level of the fusion protein when linked to CBHI. We found that this new construct (TrEGII-TeTrCBHI, Fusion 3) had an increased secretion level of at least threefold in L. starkeyi compared to the expression level of the chimeric TeTrCBHI. However, the same improvements were not observed when Fusion 3 construct was expressed in S. cerevisiae and Y. lipolytica. Digestion of pretreated corn stover with the secretomes of Y. lipolytica and L. starkeyi showed that conversion was much better using Y. lipolytica secretomes (50% versus 29%, respectively). In Y. lipolytica, TeTrCBHI performed better than the fusion construct. Furthermore, S. cerevisiae expression of Fusion 3 construct was poor and only minimal activity was observed when acting on the substrate, pNP-cellobiose. No activity was observed for the pNP-lactose substrate. Clearly, this approach is not universally applicable to all yeasts, but works in specific cases. With purified protein and soluble substrates, the exoglucanase activity of the GH7 domain embedded in the Fusion 3 construct in L. starkeyi was significantly higher than that of the GH7 domain in TeTrCBHI expressed alone. It is probable that a higher fraction of fusion construct CBHI is in an active form in Fusion 3 compared to just TeTrCBHI. We conclude that the strategy of leading TeTrCBHI expression with a linked TrEGII module significantly improved the expression of active CBHI in L. starkeyi.
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Affiliation(s)
- Qi Xu
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Markus Alahuhta
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Hui Wei
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Eric P. Knoshaug
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Wei Wang
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - John O. Baker
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
| | - Todd Vander Wall
- 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
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401 USA
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13
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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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14
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The Role of Yeast-Surface-Display Techniques in Creating Biocatalysts for Consolidated BioProcessing. Catalysts 2018. [DOI: 10.3390/catal8030094] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Climate change is directly linked to the rapid depletion of our non-renewable fossil resources and has posed concerns on sustainability. Thus, imploring the need for us to shift from our fossil based economy to a sustainable bioeconomy centered on biomass utilization. The efficient bioconversion of lignocellulosic biomass (an ideal feedstock) to a platform chemical, such as bioethanol, can be achieved via the consolidated bioprocessing technology, termed yeast surface engineering, to produce yeasts that are capable of this feat. This approach has various strategies that involve the display of enzymes on the surface of yeast to degrade the lignocellulosic biomass, then metabolically convert the degraded sugars directly into ethanol, thus elevating the status of yeast from an immobilization material to a whole-cell biocatalyst. The performance of the engineered strains developed from these strategies are presented, visualized, and compared in this article to highlight the role of this technology in moving forward to our quest against climate change. Furthermore, the qualitative assessment synthesized in this work can serve as a reference material on addressing the areas of improvement of the field and on assessing the capability and potential of the different yeast surface display strategies on the efficient degradation, utilization, and ethanol production from lignocellulosic biomass.
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15
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Woon JSK, Mackeen MM, Illias RM, Mahadi NM, Broughton WJ, Murad AMA, Abu Bakar FD. Cellobiohydrolase B of Aspergillus niger over-expressed in Pichia pastoris stimulates hydrolysis of oil palm empty fruit bunches. PeerJ 2017; 5:e3909. [PMID: 29038760 PMCID: PMC5641429 DOI: 10.7717/peerj.3909] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 09/19/2017] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Aspergillus niger, along with many other lignocellulolytic fungi, has been widely used as a commercial workhorse for cellulase production. A fungal cellulase system generally includes three major classes of enzymes i.e., β-glucosidases, endoglucanases and cellobiohydrolases. Cellobiohydrolases (CBH) are vital to the degradation of crystalline cellulose present in lignocellulosic biomass. However, A. niger naturally secretes low levels of CBH. Hence, recombinant production of A. niger CBH is desirable to increase CBH production yield and also to allow biochemical characterisation of the recombinant CBH from A. niger. METHODS In this study, the gene encoding a cellobiohydrolase B (cbhB) from A. niger ATCC 10574 was cloned and expressed in the methylotrophic yeast Pichia pastoris X-33. The recombinant CBHB was purified and characterised to study its biochemical and kinetic characteristics. To evaluate the potential of CBHB in assisting biomass conversion, CBHB was supplemented into a commercial cellulase preparation (Cellic® CTec2) and was used to hydrolyse oil palm empty fruit bunch (OPEFB), one of the most abundant lignocellulosic waste from the palm oil industry. To attain maximum saccharification, enzyme loadings were optimised by response surface methodology and the optimum point was validated experimentally. Hydrolysed OPEFB samples were analysed using attenuated total reflectance FTIR spectroscopy (ATR-FTIR) to screen for any compositional changes upon enzymatic treatment. RESULTS Recombinant CBHB was over-expressed as a hyperglycosylated protein attached to N-glycans. CBHB was enzymatically active towards soluble substrates such as 4-methylumbelliferyl-β-D-cellobioside (MUC), p-nitrophenyl-cellobioside (pNPC) and p-nitrophenyl-cellobiotrioside (pNPG3) but was not active towards crystalline substrates like Avicel® and Sigmacell cellulose. Characterisation of purified CBHB using MUC as the model substrate revealed that optimum catalysis occurred at 50 °C and pH 4 but the enzyme was stable between pH 3 to 10 and 30 to 80 °C. Although CBHB on its own was unable to digest crystalline substrates, supplementation of CBHB (0.37%) with Cellic® CTec2 (30%) increased saccharification of OPEFB by 27%. Compositional analyses of the treated OPEFB samples revealed that CBHB supplementation reduced peak intensities of both crystalline cellulose Iα and Iβ in the treated OPEFB samples. DISCUSSION Since CBHB alone was inactive against crystalline cellulose, these data suggested that it might work synergistically with other components of Cellic® CTec2. CBHB supplements were desirable as they further increased hydrolysis of OPEFB when the performance of Cellic® CTec2 was theoretically capped at an enzyme loading of 34% in this study. Hence, A. niger CBHB was identified as a potential supplementary enzyme for the enzymatic hydrolysis of OPEFB.
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Affiliation(s)
- James Sy-Keen Woon
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia.,Present address: Newcastle University Medicine Malaysia, Iskandar Puteri, Johor, Malaysia
| | - Mukram M Mackeen
- School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia.,Institute of Systems Biology (INBIOSIS), Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
| | - Rosli M Illias
- Department of Bioprocess Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia
| | - Nor M Mahadi
- Institute of Systems Biology (INBIOSIS), Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia.,Malaysia Genome Institute, Kajang, Selangor, Malaysia
| | - William J Broughton
- Department 4 (Materials & Environment), Federal Institute of Materials Research and Testing, Berlin, Germany
| | - Abdul Munir Abdul Murad
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
| | - Farah Diba Abu Bakar
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
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16
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Kroukamp H, den Haan R, la Grange DC, Sibanda N, Foulquié‐Moreno MR, Thevelein JM, van Zyl WH. Strain Breeding Enhanced Heterologous Cellobiohydrolase Secretion by
Saccharomyces cerevisiae
in a Protein Specific Manner. Biotechnol J 2017; 12. [DOI: 10.1002/biot.201700346] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 08/10/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Heinrich Kroukamp
- Department of MicrobiologyUniversity of StellenboschStellenboschSouth Africa
| | - Riaan den Haan
- Department of BiotechnologyUniversity of Western CapeBellvilleSouth Africa
| | - Daniël C. la Grange
- Unit of Environmental Sciences and ManagementNorth‐West UniversityPotchefstroomSouth Africa
| | - Ntsako Sibanda
- Department of Biochemistry, Microbiology and BiotechnologyUniversity of LimpopoSovengaSouth Africa
| | - Maria R. Foulquié‐Moreno
- Institute of Botany and MicrobiologyKU LeuvenLeuven‐HeverleeBelgium
- Department of Molecular Microbiology, VIBLeuven‐HeverleeBelgium
| | - Johan M. Thevelein
- Institute of Botany and MicrobiologyKU LeuvenLeuven‐HeverleeBelgium
- Department of Molecular Microbiology, VIBLeuven‐HeverleeBelgium
| | - Willem H. van Zyl
- Department of MicrobiologyUniversity of StellenboschStellenboschSouth Africa
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17
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Song X, Liu Q, Mao J, Wu Y, Li Y, Gao K, Zhang X, Bai Y, Xu H, Qiao M. POT1-mediated δ-integration strategy for high-copy, stable expression of heterologous proteins in Saccharomyces cerevisiae. FEMS Yeast Res 2017; 17:4083647. [DOI: 10.1093/femsyr/fox064] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 08/16/2017] [Indexed: 12/18/2022] Open
Affiliation(s)
- Xiaofei Song
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Quanli Liu
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Jiwei Mao
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Yuzhen Wu
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Yuanzi Li
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Kai Gao
- Tianjin Academy of Environmental Sciences, No. 17 Fukang Road, Nankai District, Tianjin, China
| | - Xiuming Zhang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Yanling Bai
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Haijin Xu
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Mingqiang Qiao
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
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18
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Xu Q, Knoshaug EP, Wang W, Alahuhta M, Baker JO, Yang S, Vander Wall T, Decker SR, Himmel ME, Zhang M, Wei H. Expression and secretion of fungal endoglucanase II and chimeric cellobiohydrolase I in the oleaginous yeast Lipomyces starkeyi. Microb Cell Fact 2017; 16:126. [PMID: 28738851 PMCID: PMC5525229 DOI: 10.1186/s12934-017-0742-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 07/13/2017] [Indexed: 11/29/2022] Open
Abstract
Background Lipomyces starkeyi is one of the leading lipid-producing microorganisms reported to date; its genetic transformation was only recently reported. Our aim is to engineer L. starkeyi to serve in consolidated bioprocessing (CBP) to produce lipid or fatty acid-related biofuels directly from abundant and low-cost lignocellulosic substrates. Results To evaluate L. starkeyi in this role, we first conducted a genome analysis, which revealed the absence of key endo- and exocellulases in this yeast, prompting us to select and screen four signal peptides for their suitability for the overexpression and secretion of cellulase genes. To compensate for the cellulase deficiency, we chose two prominent cellulases, Trichoderma reesei endoglucanase II (EG II) and a chimeric cellobiohydrolase I (TeTrCBH I) formed by fusion of the catalytic domain from Talaromyces emersonii CBH I with the linker peptide and cellulose-binding domain from T. reesei CBH I. The systematically tested signal peptides included three peptides from native L. starkeyi and one from Yarrowia lipolytica. We found that all four signal peptides permitted secretion of active EG II. We also determined that three of these signal peptides worked for expression of the chimeric CBH I; suggesting that our design criteria for selecting these signal peptides was effective. Encouragingly, the Y. lipolytica signal peptide was able to efficiently guide secretion of the chimeric TeTrCBH I protein from L. starkeyi. The purified chimeric TeTrCBH I showed high activity against the cellulose in pretreated corn stover and the purified EG II showed high endocellulase activity measured by the CELLG3 (Megazyme) method. Conclusions Our results suggest that L. starkeyi is capable of expressing and secreting core fungal cellulases. Moreover, the purified EG II and chimeric TeTrCBH I displayed significant and potentially useful enzymatic activities, demonstrating that engineered L. starkeyi has the potential to function as an oleaginous CBP strain for biofuel production. The effectiveness of the tested secretion signals will also benefit future secretion of other heterologous proteins in L. starkeyi and, given the effectiveness of the cross-genus secretion signal, possibly other oleaginous yeasts as well. Electronic supplementary material The online version of this article (doi:10.1186/s12934-017-0742-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Qi Xu
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Eric P Knoshaug
- National Bioenergy 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
| | - John O Baker
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Shihui Yang
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA.,Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan, 430062, People's Republic of China
| | - Todd Vander Wall
- 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.
| | - Hui Wei
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA.
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19
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Yang P, Zhang H, Jiang S. Construction of recombinant sestc Saccharomyces cerevisiae for consolidated bioprocessing, cellulase characterization, and ethanol production by in situ fermentation. 3 Biotech 2016; 6:192. [PMID: 28330264 PMCID: PMC5010821 DOI: 10.1007/s13205-016-0512-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/28/2016] [Indexed: 12/04/2022] Open
Abstract
Bioethanol is an important oil substitute produced by the sugar fermentation process. To improve the efficiency of cellulase expression of Saccharomyces cerevisiae, a eukaryotic expression vector harboring a single-enzyme-system-three-cellulase gene (sestc) was integrated into the S. cerevisiae genome by the protoplast method. Using PCR screening, RT-PCR, and “transparent circle” detection, several recombinant S. cerevisiae strains, capable of efficiently expressing the heterogeneous cellulase, were selected. The total activity of cellulase, endo-β-D-glucanase, exo-β-D-glucanase, and xylanase of the recombinant S. cerevisiae transformant (designated number 14) was 1.1, 378, 1.44, and 164 U ml−1, respectively, which was 27.5-, 63-, 24-, and 19-fold higher than that of the wild-type strain. The concentration of ethanol produced by the engineered S. cerevisiae strain was 8.1 gl−1, with wheat bran as the carbon source, under submerged conditions; this was 57.86-fold higher than that produced by the wild-type strain (0.14 gl−1).
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Affiliation(s)
- Peizhou Yang
- The Key Laboratory for Agricultural Products Processing of Anhui Province, College of Food Science and Technology, Hefei University of Technology, Tunxi Road 193, Hefei, 230009, Anhui, China.
| | - Haifeng Zhang
- The Key Laboratory for Agricultural Products Processing of Anhui Province, College of Food Science and Technology, Hefei University of Technology, Tunxi Road 193, Hefei, 230009, Anhui, China
| | - Shaotong Jiang
- The Key Laboratory for Agricultural Products Processing of Anhui Province, College of Food Science and Technology, Hefei University of Technology, Tunxi Road 193, Hefei, 230009, Anhui, China
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20
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Sun FF, Bai R, Yang H, Wang F, He J, Wang C, Tu M. Heterologous expression of codon optimized Trichoderma reesei Cel6A in Pichia pastoris. Enzyme Microb Technol 2016; 92:107-16. [DOI: 10.1016/j.enzmictec.2016.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/27/2016] [Accepted: 07/12/2016] [Indexed: 01/23/2023]
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21
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Abstract
The development of separation methods for the analysis and resolution of chiral drugs and solutes has been an area of ongoing interest in pharmaceutical research. The use of proteins as chiral binding agents in high-performance liquid chromatography (HPLC) has been an approach that has received particular attention in such work. This report provides an overview of proteins that have been used as binding agents to create chiral stationary phases (CSPs) and in the use of chromatographic methods to study these materials and protein-based chiral separations. The supports and methods that have been employed to prepare protein-based CSPs will also be discussed and compared. Specific types of CSPs that are considered include those that employ serum transport proteins (e.g., human serum albumin, bovine serum albumin, and alpha1-acid glycoprotein), enzymes (e.g., penicillin G acylase, cellobiohydrolases, and α-chymotrypsin) or other types of proteins (e.g., ovomucoid, antibodies, and avidin or streptavidin). The properties and applications for each type of protein and CSP will also be discussed in terms of their use in chromatography and chiral separations.
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Affiliation(s)
- Cong Bi
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Xiwei Zheng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Shiden Azaria
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Sandya Beeram
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Zhao Li
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - David S. Hage
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
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22
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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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23
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Behera SS, Ray RC. Solid state fermentation for production of microbial cellulases: Recent advances and improvement strategies. Int J Biol Macromol 2016; 86:656-69. [DOI: 10.1016/j.ijbiomac.2015.10.090] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 12/23/2022]
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24
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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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25
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Hasunuma T, Ishii J, Kondo A. Rational design and evolutional fine tuning of Saccharomyces cerevisiae for biomass breakdown. Curr Opin Chem Biol 2015; 29:1-9. [DOI: 10.1016/j.cbpa.2015.06.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Revised: 06/06/2015] [Accepted: 06/08/2015] [Indexed: 12/31/2022]
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26
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Van Zyl JHD, Den Haan R, Van Zyl WH. Overexpression of native Saccharomyces cerevisiae ER-to-Golgi SNARE genes increased heterologous cellulase secretion. Appl Microbiol Biotechnol 2015; 100:505-18. [PMID: 26450509 DOI: 10.1007/s00253-015-7022-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 08/14/2015] [Accepted: 09/05/2015] [Indexed: 12/30/2022]
Abstract
Soluble N-ethylmaleimide-sensitive factor attachment receptor proteins (SNAREs) are essential components of the yeast protein-trafficking machinery and are required at the majority of membrane fusion events in the cell, where they facilitate SNARE-mediated fusion between the protein transport vesicles, the various membrane-enclosed organelles and, ultimately, the plasma membrane. We have demonstrated an increase in secretory titers for the Talaromyces emersonii Cel7A (Te-Cel7A, a cellobiohydrolase) and the Saccharomycopsis fibuligera Cel3A (Sf-Cel3A, a β-glucosidase) expressed in Saccharomyces cerevisiae through single and co-overexpression of some of the endoplasmic reticulum (ER)-to-Golgi SNAREs (BOS1, BET1, SEC22 and SED5). Overexpression of SED5 yielded the biggest improvements for both of the cellulolytic reporter proteins tested, with maximum increases in extracellular enzyme activity of 22 % for the Sf-Cel3A and 68 % for the Te-Cel7A. Co-overexpression of the ER-to-Golgi SNAREs yielded proportionately smaller increases for the Te-Cel7A (46 %), with the Sf-Cel3A yielding no improvement. Co-overexpression of the most promising exocytic SNARE components identified in literature for secretory enhancement of the cellulolytic proteins tested (SSO1 for Sf-Cel3A and SNC1 for Te-Cel7A) with the most effective ER-to-Golgi SNARE components identified in this study (SED5 for both Sf-Cel3A and Te-Cel7A) yielded variable results, with Sf-Cel3A improved by 131 % and Te-Cel7A yielding no improvement. Improvements were largely independent of gene dosage as all strains only integrated single additional SNARE gene copies, with episomal variance between the most improved strains shown to be insignificant. This study has added further credence to the notion that SNARE proteins fulfil an essential role within a larger cascade of secretory machinery components that could contribute significantly to future improvements to S. cerevisiae as protein production host.
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Affiliation(s)
- John Henry D Van Zyl
- Department of Microbiology, Stellenbosch University, Stellenbosch, 7602, South Africa
| | - Riaan Den Haan
- Department of Biotechnology, University of the Western Cape, Bellville, 7530, South Africa
| | - Willem H Van Zyl
- Department of Microbiology, Stellenbosch University, Stellenbosch, 7602, South Africa.
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27
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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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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: 27] [Impact Index Per Article: 3.0] [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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Zoglowek M, Lübeck PS, Ahring BK, Lübeck M. Heterologous expression of cellobiohydrolases in filamentous fungi – An update on the current challenges, achievements and perspectives. Process Biochem 2015. [DOI: 10.1016/j.procbio.2014.12.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Tanaka T, Kondo A. Cell-surface display of enzymes by the yeast Saccharomyces cerevisiae for synthetic biology. FEMS Yeast Res 2015; 15:1-9. [PMID: 25243459 DOI: 10.1111/1567-1364.12212] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 05/09/2014] [Accepted: 09/15/2014] [Indexed: 01/26/2023] Open
Abstract
In yeast cell-surface displays, functional proteins, such as cellulases, are genetically fused to an anchor protein and expressed on the cell surface. Saccharomyces cerevisiae, which is often utilized as a cell factory for the production of fuels, chemicals, and proteins, is the most commonly used yeast for cell-surface display. To construct yeast cells with a desired function, such as the ability to utilize cellulose as a substrate for bioethanol production, cell-surface display techniques for the efficient expression of enzymes on the cell membrane need to be combined with metabolic engineering approaches for manipulating target pathways within cells. In this Minireview, we summarize the recent progress of biorefinery fields in the development and application of yeast cell-surface displays from a synthetic biology perspective and discuss approaches for further enhancing cell-surface display efficiency.
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Affiliation(s)
- Tsutomu Tanaka
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Nada, Kobe, Japan
| | - Akihiko Kondo
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Nada, Kobe, Japan
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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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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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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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Current challenges in commercially producing biofuels from lignocellulosic biomass. ISRN BIOTECHNOLOGY 2014; 2014:463074. [PMID: 25937989 PMCID: PMC4393053 DOI: 10.1155/2014/463074] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 02/19/2014] [Indexed: 11/17/2022]
Abstract
Biofuels that are produced from biobased materials are a good alternative to petroleum based fuels. They offer several benefits to society and the environment. Producing second generation biofuels is even more challenging than producing first generation biofuels due the complexity of the biomass and issues related to producing, harvesting, and transporting less dense biomass to centralized biorefineries. In addition to this logistic challenge, other challenges with respect to processing steps in converting biomass to liquid transportation fuel like pretreatment, hydrolysis, microbial fermentation, and fuel separation still exist and are discussed in this review. The possible coproducts that could be produced in the biorefinery and their importance to reduce the processing cost of biofuel are discussed. About $1 billion was spent in the year 2012 by the government agencies in US to meet the mandate to replace 30% existing liquid transportation fuels by 2022 which is 36 billion gallons/year. Other countries in the world have set their own targets to replace petroleum fuel by biofuels. Because of the challenges listed in this review and lack of government policies to create the demand for biofuels, it may take more time for the lignocellulosic biofuels to hit the market place than previously projected.
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35
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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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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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Teixeira RSS, da Silva AS, Kim HW, Ishikawa K, Endo T, Lee SH, Bon EPS. Use of cellobiohydrolase-free cellulase blends for the hydrolysis of microcrystalline cellulose and sugarcane bagasse pretreated by either ball milling or ionic liquid [Emim][Ac]. BIORESOURCE TECHNOLOGY 2013; 149:551-5. [PMID: 24091019 DOI: 10.1016/j.biortech.2013.09.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 08/31/2013] [Accepted: 09/03/2013] [Indexed: 05/22/2023]
Abstract
This study investigated the requirement of cellobiohydrolases (CBH) for saccharification of microcrystalline cellulose and sugarcane bagasse pretreated either by ball milling (BM) or by ionic liquid (IL) [Emim][Ac]. Hydrolysis was done using CBH-free blends of Pyrococcus horikoshii endoglucanase (EG) plus Pyrococcus furiosus β-glucosidase (EGPh/BGPf) or Optimash™ BG while Acremonium Cellulase was used as control. IL-pretreated substrates were hydrolyzed more effectively by CBH-free enzymes than were the BM-pretreated substrates. IL-treatment decreased the crystallinity and increased the specific surface area (SSA), whereas BM-treatment decreased the crystallinity without increasing the SSA. The hydrolysis of IL-treated cellulose by EGPh/BGPf showed a saccharification rate of 3.92 g/Lh and a glucose yield of 81% within 9h. These results indicate the efficiency of CBH-free enzymes for the hydrolysis of IL-treated substrates.
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Affiliation(s)
- Ricardo Sposina Sobral Teixeira
- Federal University of Rio de Janeiro, Chemistry Institute, Av.Athos da Silveira Ramos, 149 - Centro de Tecnologia, Bloco A, Cidade Universitária, CEP 21941-909, Rio de Janeiro, RJ, Brazil
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Recent progress in metabolic engineering for the production of biofuels and biochemicals from renewable sources with particular emphasis on catabolite regulation and its modulation. Process Biochem 2013. [DOI: 10.1016/j.procbio.2013.02.032] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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