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Rossouw M, Cripwell RA, Vermeulen RR, van Staden AD, van Zyl WH, Dicks LMT, Viljoen-Bloom M. Heterologous Expression of Plantaricin 423 and Mundticin ST4SA in Saccharomyces cerevisiae. Probiotics Antimicrob Proteins 2024; 16:845-861. [PMID: 37171691 PMCID: PMC11126478 DOI: 10.1007/s12602-023-10082-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/27/2023] [Indexed: 05/13/2023]
Abstract
Antimicrobial peptides or bacteriocins are excellent candidates for alternative antimicrobials, but high manufacturing costs limit their applications. Recombinant gene expression offers the potential to produce these peptides more cost-effectively at a larger scale. Saccharomyces cerevisiae is a popular host for recombinant protein production, but with limited success reported on antimicrobial peptides. Individual recombinant S. cerevisiae strains were constructed to secrete two class IIa bacteriocins, plantaricin 423 (PlaX) and mundticin ST4SA (MunX). The native and codon-optimised variants of the plaA and munST4SA genes were cloned into episomal expression vectors containing either the S. cerevisiae alpha mating factor (MFα1) or the Trichoderma reesei xylanase 2 (XYNSEC) secretion signal sequences. The recombinant peptides retained their activity and stability, with the MFα1 secretion signal superior to the XYNSEC secretion signal for both bacteriocins. An eight-fold increase in activity against Listeria monocytogenes was observed for MunX after codon optimisation, but not for PlaX-producing strains. After HPLC-purification, the codon-optimised genes yielded 20.9 mg/L of MunX and 18.4 mg/L of PlaX, which displayed minimum inhibitory concentrations (MICs) of 108.52 nM and 1.18 µM, respectively, against L. monocytogenes. The yields represent a marked improvement relative to an Escherichia coli expression system previously reported for PlaX and MunX. The results demonstrated that S. cerevisiae is a promising host for recombinant bacteriocin production that requires a simple purification process, but the efficacy is sensitive to codon usage and secretion signals.
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Affiliation(s)
- Michelle Rossouw
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Rosemary A Cripwell
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Ross R Vermeulen
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Anton D van Staden
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
- Department of Physiological Sciences, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Willem H van Zyl
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Leon M T Dicks
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Marinda Viljoen-Bloom
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
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2
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Minnaar L, den Haan R. Engineering natural isolates of Saccharomyces cerevisiae for consolidated bioprocessing of cellulosic feedstocks. Appl Microbiol Biotechnol 2023; 107:7013-7028. [PMID: 37688599 PMCID: PMC10589140 DOI: 10.1007/s00253-023-12729-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 08/03/2023] [Accepted: 08/06/2023] [Indexed: 09/11/2023]
Abstract
Saccharomyces cerevisiae has gained much attention as a potential host for cellulosic bioethanol production using consolidated bioprocessing (CBP) methodologies, due to its high-ethanol-producing titres, heterologous protein production capabilities, and tolerance to various industry-relevant stresses. Since the secretion levels of heterologous proteins are generally low in domesticated strains of S. cerevisiae, natural isolates may offer a more diverse genetic background for improved heterologous protein secretion, while also displaying greater robustness to process stresses. In this study, the potential of natural and industrial S. cerevisiae strains to secrete a core set of cellulases (CBH1, CBH2, EG2, and BGL1), encoded by genes integrated using CRISPR/Cas9 tools, was evaluated. High levels of heterologous protein production were associated with a reduced maximal growth rate and with slight changes in overall strain robustness, compared to the parental strains. The natural isolate derivatives YI13_BECC and YI59_BECC displayed superior secretion capacity for the heterologous cellulases at high incubation temperature and in the presence of acetic acid, respectively, compared to the reference industrial strain MH1000_BECC. These strains also exhibited multi-tolerance to several fermentation-associated and secretion stresses. Cultivation of the strains on crystalline cellulose in oxygen-limited conditions yielded ethanol concentrations in the range of 4-4.5 g/L, representing 35-40% of the theoretical maximum ethanol yield after 120 h, without the addition of exogenous enzymes. This study therefore highlights the potential of these natural isolates to be used as chassis organisms in CBP bioethanol production. KEY POINTS: • Process-related fermentation stresses influence heterologous protein production. • Transformants produced up to 4.5 g/L ethanol, ~ 40% of the theoretical yield in CBP. • CRISPR/Cas9 was feasible for integrating genes in natural S. cerevisiae isolates.
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Affiliation(s)
- Letitia Minnaar
- Department of Biotechnology, University of the Western Cape, Bellville, South Africa
| | - Riaan den Haan
- Department of Biotechnology, University of the Western Cape, Bellville, South Africa.
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3
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Myburgh MW, Favaro L, van Zyl WH, Viljoen-Bloom M. Engineered yeast for the efficient hydrolysis of polylactic acid. BIORESOURCE TECHNOLOGY 2023; 378:129008. [PMID: 37011843 DOI: 10.1016/j.biortech.2023.129008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 03/28/2023] [Accepted: 03/31/2023] [Indexed: 06/19/2023]
Abstract
Polylactic acid (PLA) is a major contributor to the global bioplastic production capacity. However, post-consumer PLA waste is not fully degraded during non-optimal traditional organic waste treatment processes and can persist in nature for many years. Efficient enzymatic hydrolysis of PLA would contribute to cleaner, more energy-efficient, environmentally friendly waste management processes. However, high costs and a lack of effective enzyme producers curtail the large-scale application of such enzymatic systems. This study reports the recombinant expression of a fungal cutinase-like enzyme (CLE1) in the yeast Saccharomyces cerevisiae, which produced a crude supernatant that efficiently hydrolyses different types of PLA materials. The codon-optimised Y294[CLEns] strain delivered the best enzyme production and hydrolysis capabilities, releasing up to 9.44 g/L lactic acid from 10 g/L PLA films with more than 40% loss in film weight. This work highlights the potential of fungal hosts producing PLA hydrolases for future commercial applications in PLA recycling.
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Affiliation(s)
- Marthinus W Myburgh
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa; Department of Agronomy Food Natural Resources Animals and Environment (DAFNAE), Padova University, Agripolis, Viale dell'Università 16, 35020 Legnaro, Padova, Italy
| | - Lorenzo Favaro
- Department of Agronomy Food Natural Resources Animals and Environment (DAFNAE), Padova University, Agripolis, Viale dell'Università 16, 35020 Legnaro, Padova, Italy
| | - Willem H van Zyl
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - Marinda Viljoen-Bloom
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
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4
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den Haan R, Rose SH, Cripwell RA, Trollope KM, Myburgh MW, Viljoen-Bloom M, van Zyl WH. Heterologous production of cellulose- and starch-degrading hydrolases to expand Saccharomyces cerevisiae substrate utilization: Lessons learnt. Biotechnol Adv 2021; 53:107859. [PMID: 34678441 DOI: 10.1016/j.biotechadv.2021.107859] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 12/28/2022]
Abstract
Selected strains of Saccharomyces cerevisiae are used for commercial bioethanol production from cellulose and starch, but the high cost of exogenous enzymes for substrate hydrolysis remains a challenge. This can be addressed through consolidated bioprocessing (CBP) where S. cerevisiae strains are engineered to express recombinant glycoside hydrolases during fermentation. Looking back at numerous strategies undertaken over the past four decades to improve recombinant protein production in S. cerevisiae, it is evident that various steps in the protein production "pipeline" can be manipulated depending on the protein of interest and its anticipated application. In this review, we briefly introduce some of the strategies and highlight lessons learned with regards to improved transcription, translation, post-translational modification and protein secretion of heterologous hydrolases. We examine how host strain selection and modification, as well as enzyme compatibility, are crucial determinants for overall success. Finally, we discuss how lessons from heterologous hydrolase expression can inform modern synthetic biology and genome editing tools to provide process-ready yeast strains in future. However, it is clear that the successful expression of any particular enzyme is still unpredictable and requires a trial-and-error approach.
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Affiliation(s)
- Riaan den Haan
- Department of Biotechnology, University of the Western Cape, Bellville, South Africa
| | - Shaunita H Rose
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Rosemary A Cripwell
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Kim M Trollope
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Marthinus W Myburgh
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | | | - Willem H van Zyl
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa.
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5
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Wightman ELI, Kroukamp H, Pretorius IS, Paulsen IT, Nevalainen HKM. Rapid optimisation of cellulolytic enzymes ratios in Saccharomyces cerevisiae using in vitro SCRaMbLE. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:182. [PMID: 33292481 PMCID: PMC7607656 DOI: 10.1186/s13068-020-01823-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 10/23/2020] [Indexed: 05/12/2023]
Abstract
BACKGROUND For the economic production of biofuels and other valuable products from lignocellulosic waste material, a consolidated bioprocessing (CBP) organism is required. With efficient fermentation capability and attractive industrial qualities, Saccharomyces cerevisiae is a preferred candidate and has been engineered to produce enzymes that hydrolyze cellulosic biomass. Efficient cellulose hydrolysis requires the synergistic action of several enzymes, with the optimum combined activity ratio dependent on the composition of the substrate. RESULTS In vitro SCRaMbLE generated a library of plasmids containing different ratios of a β-glucosidase gene (CEL3A) from Saccharomycopsis fibuligera and an endoglucanase gene (CEL5A) from Trichoderma reesei. S. cerevisiae, transformed with the plasmid library, displayed a range of individual enzyme activities and synergistic capabilities. Furthermore, we show for the first time that 4,6-O-(3-ketobutylidene)-4-nitrophenyl-β-D-cellopentaoside (BPNPG5) is a suitable substrate to determine synergistic Cel3A and Cel5A action and an accurate predictive model for this synergistic action was devised. Strains with highest BPNPG5 activity had an average CEL3A and CEL5A gene cassette copy number of 1.3 ± 0.6 and 0.8 ± 0.2, respectively (ratio of 1.6:1). CONCLUSIONS Here, we describe a synthetic biology approach to rapidly optimise gene copy numbers to achieve efficient synergistic substrate hydrolysis. This study demonstrates how in vitro SCRaMbLE can be applied to rapidly combine gene constructs in various ratios to allow screening of synergistic enzyme activities for efficient substrate hydrolysis.
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Affiliation(s)
- Elizabeth L I Wightman
- Centre of Excellence in Synthetic Biology, Department of Molecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Heinrich Kroukamp
- Centre of Excellence in Synthetic Biology, Department of Molecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW, 2109, Australia.
| | | | - Ian T Paulsen
- Centre of Excellence in Synthetic Biology, Department of Molecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW, 2109, Australia
| | - Helena K M Nevalainen
- Centre of Excellence in Synthetic Biology, Department of Molecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia
- Biomolecular Discovery and Design Research Centre, Macquarie University, Sydney, NSW, 2109, Australia
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6
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Bermejo PM, Raghavendran V, Gombert AK. Neither 1G nor 2G fuel ethanol: setting the ground for a sugarcane-based biorefinery using an iSUCCELL yeast platform. FEMS Yeast Res 2020; 20:5836716. [PMID: 32401320 DOI: 10.1093/femsyr/foaa027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 05/11/2020] [Indexed: 11/12/2022] Open
Abstract
First-generation (1G) fuel ethanol production in sugarcane-based biorefineries is an established economic enterprise in Brazil. Second-generation (2G) fuel ethanol from lignocellulosic materials, though extensively investigated, is currently facing severe difficulties to become economically viable. Some of the challenges inherent to these processes could be resolved by efficiently separating and partially hydrolysing the cellulosic fraction of the lignocellulosic materials into the disaccharide cellobiose. Here, we propose an alternative biorefinery, where the sucrose-rich stream from the 1G process is mixed with a cellobiose-rich stream in the fermentation step. The advantages of mixing are 3-fold: (i) decreased concentrations of metabolic inhibitors that are typically produced during pretreatment and hydrolysis of lignocellulosic materials; (ii) decreased cooling times after enzymatic hydrolysis prior to fermentation; and (iii) decreased availability of free glucose for contaminating microorganisms and undesired glucose repression effects. The iSUCCELL platform will be built upon the robust Saccharomyces cerevisiae strains currently present in 1G biorefineries, which offer competitive advantage in non-aseptic environments, and into which intracellular hydrolyses of sucrose and cellobiose will be engineered. It is expected that high yields of ethanol can be achieved in a process with cell recycling, lower contamination levels and decreased antibiotic use, when compared to current 2G technologies.
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Affiliation(s)
| | - Vijayendran Raghavendran
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
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7
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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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8
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Smekenov I, Bakhtambayeva M, Bissenbayev K, Saparbayev M, Taipakova S, Bissenbaev AK. Heterologous secretory expression of β-glucosidase from Thermoascus aurantiacus in industrial Saccharomyces cerevisiae strains. Braz J Microbiol 2019; 51:107-123. [PMID: 31776864 DOI: 10.1007/s42770-019-00192-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 11/14/2019] [Indexed: 10/25/2022] Open
Abstract
The use of plant biomass for biofuel production will require efficient utilization of the sugars in lignocellulose, primarily cellobiose, because it is the major soluble by-product of cellulose and acts as a strong inhibitor, especially for cellobiohydrolase, which plays a key role in cellulose hydrolysis. Commonly used ethanologenic yeast Saccharomyces cerevisiae is unable to utilize cellobiose; accordingly, genetic engineering efforts have been made to transfer β-glucosidase genes enabling cellobiose utilization. Nonetheless, laboratory yeast strains have been employed for most of this research, and such strains may be difficult to use in industrial processes because of their generally weaker resistance to stressors and worse fermenting abilities. The purpose of this study was to engineer industrial yeast strains to ferment cellobiose after stable integration of tabgl1 gene that encodes a β-glucosidase from Thermoascus aurantiacus (TaBgl1). The recombinant S. cerevisiae strains obtained in this study secrete TaBgl1, which can hydrolyze cellobiose and produce ethanol. This study clearly indicates that the extent of glycosylation of secreted TaBgl1 depends from the yeast strains used and is greatly influenced by carbon sources (cellobiose or glucose). The recombinant yeast strains showed high osmotolerance and resistance to various concentrations of ethanol and furfural and to high temperatures. Therefore, these yeast strains are suitable for ethanol production processes with saccharified lignocellulose.
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Affiliation(s)
- Izat Smekenov
- Department of Molecular Biology and Genetics, Faculty of Biology and Biotechnology, Al-Farabi Kazakh National University, Almaty, Kazakhstan, 050040.,Scientific Research Institute of Biology and Biotechnology Problems, Al-Farabi Kazakh National University, Almaty, Kazakhstan, 050040
| | - Marzhan Bakhtambayeva
- Department of Molecular Biology and Genetics, Faculty of Biology and Biotechnology, Al-Farabi Kazakh National University, Almaty, Kazakhstan, 050040.,Scientific Research Institute of Biology and Biotechnology Problems, Al-Farabi Kazakh National University, Almaty, Kazakhstan, 050040
| | - Kudaybergen Bissenbayev
- Scientific Research Institute of Biology and Biotechnology Problems, Al-Farabi Kazakh National University, Almaty, Kazakhstan, 050040.,Nazarbayev Intellectual School, Almaty, Kazakhstan, 050044
| | - Murat Saparbayev
- Gustave Roussy Cancer Campus, CNRS UMR8200, Université Paris-Sud, F-94805, Villejuif Cedex, France
| | - Sabira Taipakova
- Department of Molecular Biology and Genetics, Faculty of Biology and Biotechnology, Al-Farabi Kazakh National University, Almaty, Kazakhstan, 050040.,Scientific Research Institute of Biology and Biotechnology Problems, Al-Farabi Kazakh National University, Almaty, Kazakhstan, 050040
| | - Amangeldy K Bissenbaev
- Department of Molecular Biology and Genetics, Faculty of Biology and Biotechnology, Al-Farabi Kazakh National University, Almaty, Kazakhstan, 050040. .,Scientific Research Institute of Biology and Biotechnology Problems, Al-Farabi Kazakh National University, Almaty, Kazakhstan, 050040.
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9
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Cagnin L, Favaro L, Gronchi N, Rose SH, Basaglia M, van Zyl WH, Casella S. Comparing laboratory and industrial yeast platforms for the direct conversion of cellobiose into ethanol under simulated industrial conditions. FEMS Yeast Res 2019; 19:5333308. [DOI: 10.1093/femsyr/foz018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 02/15/2019] [Indexed: 11/13/2022] Open
Affiliation(s)
- Lorenzo Cagnin
- Department of Agronomy Food Natural resources Animals and Enviroment (DAFNAE), University of Padova, Agripolis, Viale dell'Università 16, 35020 Legnaro (PD), Italy
| | - Lorenzo Favaro
- Department of Agronomy Food Natural resources Animals and Enviroment (DAFNAE), University of Padova, Agripolis, Viale dell'Università 16, 35020 Legnaro (PD), Italy
| | - Nicoletta Gronchi
- Department of Agronomy Food Natural resources Animals and Enviroment (DAFNAE), University of Padova, Agripolis, Viale dell'Università 16, 35020 Legnaro (PD), Italy
| | - Shaunita Hellouise Rose
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, Stellenbosch, South Africa
| | - Marina Basaglia
- Department of Agronomy Food Natural resources Animals and Enviroment (DAFNAE), University of Padova, Agripolis, Viale dell'Università 16, 35020 Legnaro (PD), Italy
| | - Willem Heber van Zyl
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, Stellenbosch, South Africa
| | - Sergio Casella
- Department of Agronomy Food Natural resources Animals and Enviroment (DAFNAE), University of Padova, Agripolis, Viale dell'Università 16, 35020 Legnaro (PD), Italy
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10
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Investigating the biochemical and fermentation attributes of Lachancea species and strains: Deciphering the potential contribution to wine chemical composition. Int J Food Microbiol 2019; 290:273-287. [DOI: 10.1016/j.ijfoodmicro.2018.10.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/25/2018] [Accepted: 10/29/2018] [Indexed: 11/19/2022]
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11
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Gao M, Ploessl D, Shao Z. Enhancing the Co-utilization of Biomass-Derived Mixed Sugars by Yeasts. Front Microbiol 2019; 9:3264. [PMID: 30723464 PMCID: PMC6349770 DOI: 10.3389/fmicb.2018.03264] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 12/14/2018] [Indexed: 12/11/2022] Open
Abstract
Plant biomass is a promising carbon source for producing value-added chemicals, including transportation biofuels, polymer precursors, and various additives. Most engineered microbial hosts and a select group of wild-type species can metabolize mixed sugars including oligosaccharides, hexoses, and pentoses that are hydrolyzed from plant biomass. However, most of these microorganisms consume glucose preferentially to non-glucose sugars through mechanisms generally defined as carbon catabolite repression. The current lack of simultaneous mixed-sugar utilization limits achievable titers, yields, and productivities. Therefore, the development of microbial platforms capable of fermenting mixed sugars simultaneously from biomass hydrolysates is essential for economical industry-scale production, particularly for compounds with marginal profits. This review aims to summarize recent discoveries and breakthroughs in the engineering of yeast cell factories for improved mixed-sugar co-utilization based on various metabolic engineering approaches. Emphasis is placed on enhanced non-glucose utilization, discovery of novel sugar transporters free from glucose repression, native xylose-utilizing microbes, consolidated bioprocessing (CBP), improved cellulase secretion, and creation of microbial consortia for improving mixed-sugar utilization. Perspectives on the future development of biorenewables industry are provided in the end.
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Affiliation(s)
- Meirong Gao
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA, United States.,NSF Engineering Research Center for Biorenewable Chemicals (CBiRC), Iowa State University, Ames, IA, United States
| | - Deon Ploessl
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA, United States.,NSF Engineering Research Center for Biorenewable Chemicals (CBiRC), Iowa State University, Ames, IA, United States
| | - Zengyi Shao
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA, United States.,NSF Engineering Research Center for Biorenewable Chemicals (CBiRC), Iowa State University, Ames, IA, United States.,The Ames Laboratory, Iowa State University, Ames, IA, United States.,The Interdisciplinary Microbiology Program, Biorenewables Research Laboratory, Iowa State University, Ames, IA, 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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Cellobiose fermentation by Saccharomyces cerevisiae: Comparative analysis of intra versus extracellular sugar hydrolysis. Process Biochem 2018. [DOI: 10.1016/j.procbio.2018.09.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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14
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Kar B, Verma P, den Haan R, Sharma AK. Effect of N-linked glycosylation on the activity and stability of a β-glucosidase from Putranjiva roxburghii. Int J Biol Macromol 2018; 112:490-498. [DOI: 10.1016/j.ijbiomac.2018.01.201] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 01/06/2018] [Accepted: 01/30/2018] [Indexed: 12/31/2022]
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15
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The heterologous expression potential of an acid-tolerant Talaromyces pinophilus β-glucosidase in Saccharomyces cerevisiae. Folia Microbiol (Praha) 2018; 63:725-734. [DOI: 10.1007/s12223-018-0613-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 05/14/2018] [Indexed: 10/16/2022]
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16
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Ding J, Liang G, Zhang K, Hong J, Zou S, Lu H, Ma Y, Zhang M. Extra metabolic burden by displaying over secreting: Growth, fermentation and enzymatic activity in cellobiose of recombinant yeast expressing β-glucosidase. BIORESOURCE TECHNOLOGY 2018; 254:107-114. [PMID: 29413910 DOI: 10.1016/j.biortech.2017.12.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/09/2017] [Accepted: 12/11/2017] [Indexed: 06/08/2023]
Abstract
β-Glucosidase was selected to be a reporter to study metabolic burden imposed by its expression in yeast. Cell growth, fermentation yield and enzymatic activity were used as indicators of the metabolic burden borne by 14 recombinant yeast strains. Various factors were found to affect metabolic burden, including BGLI gene source, gene dose, trafficking of the enzyme (either cell-surface display or secretion), and oxygen supply. While BGLI gene from Aspergillus aculeatus provided better performance for the host cells than that from Saccharomycopsis fibuligera, displaying β-glucosidase on the cell surface generally led to lower μm, total activity and ethanol titer, and longer lag period, lower (aerobic condition) or higher (anaerobic condition) biomass yield than that of secreting β-glucosidase. The negative effect on growth increased with gene dose level until a final failure to grow. This growth difference implies that displaying β-glucosidase on the cell surface imposes an extra metabolic burden. The molecular basis and mechanisms for this phenomenon need to further be investigated in order to develop better strategies for utilizing displayed and secreted enzymes in biotechnology and yeast breeding.
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Affiliation(s)
- Juanjuan Ding
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Guohong Liang
- Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Kun Zhang
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Jiefang Hong
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China
| | - Shaolan Zou
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
| | - Haiyan Lu
- Key Laboratory of Systems Bioengineering, Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Yuanyuan Ma
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China
| | - Minhua Zhang
- Tianjin R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Key Laboratory for Green Chemical Technology of Ministry of Education, Tianjin University, Tianjin 300072, China; State Key Laboratory of Engine, Tianjin University, Tianjin 300072, China
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17
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Oh YR, Jung KA, Lee HJ, Jung GY, Park JM. A Novel 3,6-anhydro-L-galactose Dehydrogenase Produced by a Newly Isolated Raoultella ornithinolytica B6-JMP12. BIOTECHNOL BIOPROC E 2018. [DOI: 10.1007/s12257-017-0480-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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18
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Andreu C, Del Olmo ML. Yeast arming systems: pros and cons of different protein anchors and other elements required for display. Appl Microbiol Biotechnol 2018; 102:2543-2561. [PMID: 29435617 DOI: 10.1007/s00253-018-8827-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/30/2018] [Accepted: 01/31/2018] [Indexed: 12/13/2022]
Abstract
Yeast display is a powerful strategy that consists in exposing peptides or proteins of interest on the cell surface of this microorganism. Ever since initial experiments with this methodology were carried out, its scope has extended and many applications have been successfully developed in different science and technology fields. Several yeast display systems have been designed, which all involve introducting into yeast cells the gene fusions that contain the coding regions of a signal peptide, an anchor protein, to properly attach the target to the cell surface, and the protein of interest to be exposed, all of which are controlled by a strong promoter. In this work, we report the description of such elements for the alternative systems introduced by focusing particularly on anchor proteins. The comparisons made between them are included whenever possible, and the main advantages and inconveniences of each one are discussed. Despite the huge number of publications on yeast surface display and the revisions published to date, this topic has not yet been widely considered. Finally, given the growing interest in developing systems for non-Saccharomyces yeasts, the main strategies reported for some are also summarized.
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Affiliation(s)
- Cecilia Andreu
- Departament de Química Orgànica, Facultat de Farmàcia, Universitat de València, Vicent Andrés Estellés s/n. 46100 Burjassot, València, Spain
| | - Marcel Lí Del Olmo
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de València, Dr. Moliner 50, E-46100 Burjassot, València, Spain.
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19
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Kar B, Verma P, den Haan R, Sharma AK. Characterization of a recombinant thermostable β-glucosidase from Putranjiva roxburghii expressed in Saccharomyces cerevisiae and its use for efficient biomass conversion. Process Biochem 2017. [DOI: 10.1016/j.procbio.2017.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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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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21
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Parisutham V, Chandran SP, Mukhopadhyay A, Lee SK, Keasling JD. Intracellular cellobiose metabolism and its applications in lignocellulose-based biorefineries. BIORESOURCE TECHNOLOGY 2017; 239:496-506. [PMID: 28535986 DOI: 10.1016/j.biortech.2017.05.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/27/2017] [Accepted: 05/01/2017] [Indexed: 05/28/2023]
Abstract
Complete hydrolysis of cellulose has been a key characteristic of biomass technology because of the limitation of industrial production hosts to use cellodextrin, the partial hydrolysis product of cellulose. Cellobiose, a β-1,4-linked glucose dimer, is a major cellodextrin of the enzymatic hydrolysis (via endoglucanase and exoglucanase) of cellulose. Conversion of cellobiose to glucose is executed by β-glucosidase. The complete extracellular hydrolysis of celluloses has several critical barriers in biomass technology. An alternative bioengineering strategy to make the bioprocessing less challenging is to engineer microbes with the abilities to hydrolyze and assimilate the cellulosic-hydrolysate cellodextrin. Microorganisms engineered to metabolize cellobiose rather than the monomeric glucose can provide several advantages for lignocellulose-based biorefineries. This review describes the recent advances and challenges in engineering efficient intracellular cellobiose metabolism in industrial hosts. This review also describes the limitations of and future prospectives in engineering intracellular cellobiose metabolism.
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Affiliation(s)
- Vinuselvi Parisutham
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Sathesh-Prabu Chandran
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Aindrila Mukhopadhyay
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Sung Kuk Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea; School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
| | - Jay D Keasling
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Department of Chemical and Biomolecular Engineering & Department of Bioengineering, UC Berkeley, Berkeley, CA 94720, USA; Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, KogleAllé, DK2970 Hørsholm, Denmark; Synthetic Biology Engineering Research Center (Synberc), Berkeley, CA 94720, USA
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22
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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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23
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Expression of a codon-optimized β-glucosidase from Cellulomonas flavigena PR-22 in Saccharomyces cerevisiae for bioethanol production from cellobiose. Arch Microbiol 2017; 199:605-611. [PMID: 28138738 DOI: 10.1007/s00203-016-1333-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 12/13/2016] [Accepted: 12/26/2016] [Indexed: 10/20/2022]
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24
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Choo JH, Hong CP, Lim JY, Seo JA, Kim YS, Lee DW, Park SG, Lee GW, Carroll E, Lee YW, Kang HA. Whole-genome de novo sequencing, combined with RNA-Seq analysis, reveals unique genome and physiological features of the amylolytic yeast Saccharomycopsis fibuligera and its interspecies hybrid. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:246. [PMID: 27872659 PMCID: PMC5106798 DOI: 10.1186/s13068-016-0653-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 10/22/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Genomic studies on fungal species with hydrolytic activity have gained increased attention due to their great biotechnological potential for biomass-based biofuel production. The amylolytic yeast Saccharomycopsis fibuligera has served as a good source of enzymes and genes involved in saccharification. Despite its long history of use in food fermentation and bioethanol production, very little is known about the basic physiology and genomic features of S. fibuligera. RESULTS We performed whole-genome (WG) de novo sequencing and complete assembly of S. fibuligera KJJ81 and KPH12, two isolates from wheat-based Nuruk in Korea. Intriguingly, the KJJ81 genome (~38 Mb) was revealed as a hybrid between the KPH12 genome (~18 Mb) and another unidentified genome sharing 88.1% nucleotide identity with the KPH12 genome. The seven chromosome pairs of KJJ81 subgenomes exhibit highly conserved synteny, indicating a very recent hybridization event. The phylogeny inferred from WG comparisons showed an early divergence of S. fibuligera before the separation of the CTG and Saccharomycetaceae clades in the subphylum Saccharomycotina. Reconstructed carbon and sulfur metabolic pathways, coupled with RNA-Seq analysis, suggested a marginal Crabtree effect under high glucose and activation of sulfur metabolism toward methionine biosynthesis under sulfur limitation in this yeast. Notably, the lack of sulfate assimilation genes in the S. fibuligera genome reflects a unique phenotype for Saccharomycopsis clades as natural sulfur auxotrophs. Extended gene families, including novel genes involved in saccharification and proteolysis, were identified. Moreover, comparative genome analysis of S. fibuligera ATCC 36309, an isolate from chalky rye bread in Germany, revealed that an interchromosomal translocation occurred in the KPH12 genome before the generation of the KJJ81 hybrid genome. CONCLUSIONS The completely sequenced S. fibuligera genome with high-quality annotation and RNA-Seq analysis establishes an important foundation for functional inference of S. fibuligera in the degradation of fermentation mash. The gene inventory facilitates the discovery of new genes applicable to the production of novel valuable enzymes and chemicals. Moreover, as the first gapless genome assembly in the genus Saccharomycopsis including members with desirable traits for bioconversion, the unique genomic features of S. fibuligera and its hybrid will provide in-depth insights into fungal genome dynamics as evolutionary adaptation.
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Affiliation(s)
- Jin Ho Choo
- Department of Life Science, Chung-Ang University, Seoul, 06974 South Korea
| | - Chang Pyo Hong
- Theragen Bio Institute, TheragenEtex, Suwon, 16229 South Korea
| | - Jae Yun Lim
- Department of Agricultural Biotechnology, Seoul National University, Seoul, 08826 South Korea
| | - Jeong-Ah Seo
- School of Systems Biomedical Science, Soongsil University, Seoul, 06978 South Korea
| | - Young-Suk Kim
- Department of Food Science and Engineering, Ewha Womans University, Seoul, 03760 South Korea
| | - Dong Wook Lee
- Department of Life Science, Chung-Ang University, Seoul, 06974 South Korea
| | - Sin-Gi Park
- Theragen Bio Institute, TheragenEtex, Suwon, 16229 South Korea
| | - Gir Won Lee
- Theragen Bio Institute, TheragenEtex, Suwon, 16229 South Korea
| | - Emily Carroll
- School of Systems Biomedical Science, Soongsil University, Seoul, 06978 South Korea
| | - Yin-Won Lee
- Department of Agricultural Biotechnology, Seoul National University, Seoul, 08826 South Korea
| | - Hyun Ah Kang
- Department of Life Science, Chung-Ang University, Seoul, 06974 South Korea
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25
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Huang R, Guo H, Su R, Qi W, He Z. Enhanced cellulase recovery without β-glucosidase supplementation for cellulosic ethanol production using an engineered strain and surfactant. Biotechnol Bioeng 2016; 114:543-551. [DOI: 10.1002/bit.26194] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/30/2016] [Accepted: 09/26/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Renliang Huang
- Tianjin Engineering Center of Bio Gas/Oil Technology; School of Environmental Science and Engineering; Tianjin University; Tianjin China
| | - Hong Guo
- State Key Laboratory of Chemical Engineering; School of Chemical Engineering and Technology; Tianjin University; Tianjin 300072 China
| | - Rongxin Su
- State Key Laboratory of Chemical Engineering; School of Chemical Engineering and Technology; Tianjin University; Tianjin 300072 China
- Tianjin Key Laboratory of Membrane Science and Desalination Technology; Tianjin University; Tianjin China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); Tianjin China
| | - Wei Qi
- State Key Laboratory of Chemical Engineering; School of Chemical Engineering and Technology; Tianjin University; Tianjin 300072 China
- Tianjin Key Laboratory of Membrane Science and Desalination Technology; Tianjin University; Tianjin China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin); Tianjin China
| | - Zhimin He
- State Key Laboratory of Chemical Engineering; School of Chemical Engineering and Technology; Tianjin University; Tianjin 300072 China
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26
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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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27
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Inokuma K, Bamba T, Ishii J, Ito Y, Hasunuma T, Kondo A. Enhanced cell-surface display and secretory production of cellulolytic enzymes withSaccharomyces cerevisiaeSed1 signal peptide. Biotechnol Bioeng 2016; 113:2358-66. [DOI: 10.1002/bit.26008] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Kentaro Inokuma
- Organization of Advanced Science and Technology; Kobe University; Kobe Japan
| | - Takahiro Bamba
- Department of Chemical Science and Engineering; Graduate School of Engineering; Kobe University; 1-1 Rokkodai, Nada Kobe 657-8501 Japan
| | - Jun Ishii
- Organization of Advanced Science and Technology; Kobe University; Kobe Japan
| | - Yoichiro Ito
- Department of Chemical Science and Engineering; Graduate School of Engineering; Kobe University; 1-1 Rokkodai, Nada Kobe 657-8501 Japan
| | - Tomohisa Hasunuma
- Organization of Advanced Science and Technology; Kobe University; Kobe Japan
| | - Akihiko Kondo
- Department of Chemical Science and Engineering; Graduate School of Engineering; Kobe University; 1-1 Rokkodai, Nada Kobe 657-8501 Japan
- Biomass Engineering Program; RIKEN; 1-7-22 Suehiro-cho Tsurumi-ku, Yokohama Kanagawa 230-0045 Japan
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28
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Ryu S, Hipp J, Trinh CT. Activating and Elucidating Metabolism of Complex Sugars in Yarrowia lipolytica. Appl Environ Microbiol 2016; 82:1334-1345. [PMID: 26682853 PMCID: PMC4751822 DOI: 10.1128/aem.03582-15] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 12/14/2015] [Indexed: 11/20/2022] Open
Abstract
The oleaginous yeast Yarrowia lipolytica is an industrially important host for production of organic acids, oleochemicals, lipids, and proteins with broad biotechnological applications. Albeit known for decades, the unique native metabolism of Y. lipolytica for using complex fermentable sugars, which are abundant in lignocellulosic biomass, is poorly understood. In this study, we activated and elucidated the native sugar metabolism in Y. lipolytica for cell growth on xylose and cellobiose as well as their mixtures with glucose through comprehensive metabolic and transcriptomic analyses. We identified 7 putative glucose-specific transporters, 16 putative xylose-specific transporters, and 4 putative cellobiose-specific transporters that are transcriptionally upregulated for growth on respective single sugars. Y. lipolytica is capable of using xylose as a carbon source, but xylose dehydrogenase is the key bottleneck of xylose assimilation and is transcriptionally repressed by glucose. Y. lipolytica has a set of 5 extracellular and 6 intracellular β-glucosidases and is capable of assimilating cellobiose via extra- and intracellular mechanisms, the latter being dominant for growth on cellobiose as a sole carbon source. Strikingly, Y. lipolytica exhibited enhanced sugar utilization for growth in mixed sugars, with strong carbon catabolite activation for growth on the mixture of xylose and cellobiose and with mild carbon catabolite repression of glucose on xylose and cellobiose. The results of this study shed light on fundamental understanding of the complex native sugar metabolism of Y. lipolytica and will help guide inverse metabolic engineering of Y. lipolytica for enhanced conversion of biomass-derived fermentable sugars to chemicals and fuels.
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Affiliation(s)
- Seunghyun Ryu
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, USA
| | - Julie Hipp
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, USA
| | - Cong T Trinh
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, USA
- Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee, USA
- University of Tennessee, Knoxville, Tennessee, USA; Bioenergy Science Center (BESC), Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
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29
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Larue K, Melgar M, Martin VJJ. Directed evolution of a fungal β-glucosidase in Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:52. [PMID: 26949413 PMCID: PMC4778352 DOI: 10.1186/s13068-016-0470-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 02/22/2016] [Indexed: 05/13/2023]
Abstract
BACKGROUND β-glucosidases (BGLs) catalyze the hydrolysis of soluble cellodextrins to glucose and are a critical component of cellulase systems. In order to engineer Saccharomyces cerevisiae for the production of ethanol from cellulosic biomass, a BGL tailored to industrial bioconversions is needed. RESULTS We applied a directed evolution strategy to a glycosyl hydrolase family 3 (GH3) BGL from Aspergillus niger (BGL1) by expressing a library of mutated bgl1 genes in S. cerevisiae and used a two-step functional screen to identify improved enzymes. Twelve BGL variants that supported growth of S. cerevisiae on cellobiose and showed increased activity on the synthetic substrate p-nitrophenyl-β-D-glucopyranoside were identified and characterized. By performing kinetic experiments, we found that a Tyr → Cys substitution at position 305 of BGL1 dramatically reduced transglycosidation activity that causes inhibition of the hydrolytic reaction at high substrate concentrations. Targeted mutagenesis demonstrated that the position 305 residue is critical in GH3 BGLs and likely determines the extent to which transglycosidation reactions occur. We also found that a substitution at Gln(140) reduced the inhibitory effect of glucose and could be combined with the Y305C substitution to produce a BGL with decreased sensitivity to both the product and substrate. Using the crystal structure of a GH3 BGL from A. aculeatus, we mapped a group of beneficial mutations to the β/α domain of the molecule and postulate that this region modulates activity through subunit interactions. Six BGL variants were identified with substitutions in the MFα pre-sequence that was used to mediate secretion of the protein. Substitutions at Pro(21) or Val(22) of the MFα pre-sequence could produce up to a twofold increase in supernatant hydrolase activity and provides evidence that expression and/or secretion was an additional factor limiting hydrolytic activity. CONCLUSIONS Using directed evolution on BGL1, we identified a key residue that controls hydrolytic and transglycosidation reactions in GH3 BGLs. We also found that several beneficial mutations could be combined and increased the hydrolytic activity for both synthetic and natural substrates.
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Affiliation(s)
- Kane Larue
- Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke West, Montreal, QC H4B 1R6 Canada
| | - Mindy Melgar
- Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke West, Montreal, QC H4B 1R6 Canada
| | - Vincent J. J. Martin
- Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke West, Montreal, QC H4B 1R6 Canada
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Heterologously expressed Aspergillus aculeatus β-glucosidase in Saccharomyces cerevisiae is a cost-effective alternative to commercial supplementation of β-glucosidase in industrial ethanol production using Trichoderma reesei cellulases. J Biosci Bioeng 2016; 121:27-35. [DOI: 10.1016/j.jbiosc.2015.05.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 05/07/2015] [Accepted: 05/08/2015] [Indexed: 11/17/2022]
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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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Ma Y, Liu X, Yin Y, Zou C, Wang W, Zou S, Hong J, Zhang M. Expression optimization and biochemical properties of two glycosyl hydrolase family 3 beta-glucosidases. J Biotechnol 2015; 206:79-88. [PMID: 25937452 DOI: 10.1016/j.jbiotec.2015.04.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 03/26/2015] [Accepted: 04/18/2015] [Indexed: 10/23/2022]
Abstract
The β-glucosidases from Saccharomycopsis fibuligera (SfBGL1) and Trichoderma reesei (TrBGL1) were cloned and expressed in Pichia pastoris. Methanol concentration and pH significantly affected the production. The combined effects of the two factors were optimized by using the response surface method, resulting in a 137% and 84% increase in rTrBGL1 and rSfBGL1 yield compared to single-factor experiment. Structure and biochemical properties of the two enzyme were investigated and compared. They belong to glycosyl hydrolase family 3 and exhibit significant hydrolysis activity and low-level transglycosylation activity. The two enzymes show similar substrate affinity and ion-tolerance, and both of them can be activated by Cr(6+), Mn(2+) and Fe(2+). The rSfBGL1 has greater catalytic speed, higher specific activity and acid-tolerance than rTrBGL1, but rTrBGL1 is more thermostable and has higher optimal temperature than rSfBGL1. This study provides a useful and quick optimal method for recombinant enzyme production and makes a valuable comparison of biochemical properties, which opens important avenues of exploration for relationship between structure and function and further practical applications.
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Affiliation(s)
- Yuanyuan Ma
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China; Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China.
| | - Xuewei Liu
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
| | - Yanchen Yin
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
| | - Chao Zou
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
| | - Wanchao Wang
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.
| | - Shaolan Zou
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China; Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China.
| | - Jiefang Hong
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China.
| | - Minhua Zhang
- R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China; Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China.
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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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Shirley D, Oppert C, Reynolds TB, Miracle B, Oppert B, Klingeman WE, Jurat-Fuentes JL. Expression of an endoglucanase from Tribolium castaneum (TcEG1) in Saccharomyces cerevisiae. INSECT SCIENCE 2014; 21:609-618. [PMID: 24318365 DOI: 10.1111/1744-7917.12069] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/10/2013] [Indexed: 05/28/2023]
Abstract
Insects are a largely unexploited resource in prospecting for novel cellulolytic enzymes to improve the production of ethanol fuel from lignocellulosic biomass. The cost of lignocellulosic ethanol production is expected to decrease by the combination of cellulose degradation (saccharification) and fermentation of the resulting glucose to ethanol in a single process, catalyzed by the yeast Saccharomyces cerevisiae transformed to express efficient cellulases. While S. cerevisiae is an established heterologous expression system, there are no available data on the functional expression of insect cellulolytic enzymes for this species. To address this knowledge gap, S. cerevisiae was transformed to express the full-length cDNA encoding an endoglucanase from the red flour beetle, Tribolium castaneum (TcEG1), and evaluated the activity of the transgenic product (rTcEG1). Expression of the TcEG1 cDNA in S. cerevisiae was under control of the strong glyceraldehyde-3 phosphate dehydrogenase promoter. Cultured transformed yeast secreted rTcEG1 protein as a functional β-1,4-endoglucanase, which allowed transformants to survive on selective media containing cellulose as the only available carbon source. Evaluation of substrate specificity for secreted rTcEG1 demonstrated endoglucanase activity, although some activity was also detected against complex cellulose substrates. Potentially relevant to uses in biofuel production rTcEG1 activity increased with pH conditions, with the highest activity detected at pH 12. Our results demonstrate the potential for functional production of an insect cellulase in S. cerevisiae and confirm the stability of rTcEG1 activity in strong alkaline environments.
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Affiliation(s)
- Derek Shirley
- Department of Entomology and Plant Pathology, University of Tennessee
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35
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Comparative engineering of Escherichia coli for cellobiose utilization: Hydrolysis versus phosphorolysis. Metab Eng 2014; 24:9-17. [DOI: 10.1016/j.ymben.2014.04.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 03/01/2014] [Accepted: 04/14/2014] [Indexed: 11/20/2022]
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Kricka W, Fitzpatrick J, Bond U. Metabolic engineering of yeasts by heterologous enzyme production for degradation of cellulose and hemicellulose from biomass: a perspective. Front Microbiol 2014; 5:174. [PMID: 24795706 PMCID: PMC4001029 DOI: 10.3389/fmicb.2014.00174] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 03/31/2014] [Indexed: 11/13/2022] Open
Abstract
This review focuses on current approaches to metabolic engineering of ethanologenic yeast species for the production of bioethanol from complex lignocellulose biomass sources. The experimental strategies for the degradation of the cellulose and xylose-components of lignocellulose are reviewed. Limitations to the current approaches are discussed and novel solutions proposed.
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Affiliation(s)
- William Kricka
- School of Genetics and Microbiology, Department of Microbiology, Trinity College Dublin Dublin, Ireland
| | - James Fitzpatrick
- School of Genetics and Microbiology, Department of Microbiology, Trinity College Dublin Dublin, Ireland
| | - Ursula Bond
- School of Genetics and Microbiology, Department of Microbiology, Trinity College Dublin Dublin, Ireland
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37
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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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38
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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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Eriksen DT, Hsieh PCH, Lynn P, Zhao H. Directed evolution of a cellobiose utilization pathway in Saccharomyces cerevisiae by simultaneously engineering multiple proteins. Microb Cell Fact 2013; 12:61. [PMID: 23802545 PMCID: PMC3702475 DOI: 10.1186/1475-2859-12-61] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Accepted: 06/03/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The optimization of metabolic pathways is critical for efficient and economical production of biofuels and specialty chemicals. One such significant pathway is the cellobiose utilization pathway, identified as a promising route in biomass utilization. Here we describe the optimization of cellobiose consumption and ethanol productivity by simultaneously engineering both proteins of the pathway, the β-glucosidase (gh1-1) and the cellodextrin transporter (cdt-1), in an example of pathway engineering through directed evolution. RESULTS The improved pathway was assessed based on the strain specific growth rate on cellobiose, with the final mutant exhibiting a 47% increase over the wild-type pathway. Metabolite analysis of the engineered pathway identified a 49% increase in cellobiose consumption (1.78 to 2.65 g cellobiose/(L · h)) and a 64% increase in ethanol productivity (0.611 to 1.00 g ethanol/(L · h)). CONCLUSIONS By simultaneously engineering multiple proteins in the pathway, cellobiose utilization in S. cerevisiae was improved. This optimization can be generally applied to other metabolic pathways, provided a selection/screening method is available for the desired phenotype. The improved in vivo cellobiose utilization demonstrated here could help to decrease the in vitro enzyme load in biomass pretreatment, ultimately contributing to a reduction in the high cost of biofuel production.
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Buschke N, Schäfer R, Becker J, Wittmann C. Metabolic engineering of industrial platform microorganisms for biorefinery applications--optimization of substrate spectrum and process robustness by rational and evolutive strategies. BIORESOURCE TECHNOLOGY 2013; 135:544-554. [PMID: 23260271 DOI: 10.1016/j.biortech.2012.11.047] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 11/07/2012] [Accepted: 11/09/2012] [Indexed: 06/01/2023]
Abstract
Bio-based production promises a sustainable route to myriads of chemicals, materials and fuels. With regard to eco-efficiency, its future success strongly depends on a next level of bio-processes using raw materials beyond glucose. Such renewables, i.e., polymers, complex substrate mixtures and diluted waste streams, often cannot be metabolized naturally by the producing organisms. This particularly holds for well-known microorganisms from the traditional sugar-based biotechnology, including Escherichia coli, Corynebacterium glutamicum and Saccharomyces cerevisiae which have been engineered successfully to produce a broad range of products from glucose. In order to make full use of their production potential within the bio-refinery value chain, they have to be adapted to various feed-stocks of interest. This review focuses on the strategies to be applied for this purpose which combine rational and evolutive approaches. Hereby, the three industrial platform microorganisms, E. coli, C. glutamicum and S. cerevisiae are highlighted due to their particular importance.
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Affiliation(s)
- Nele Buschke
- Institute of Biochemical Engineering, Technische Universität Braunschweig, Germany
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41
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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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Single amino acid substitutions in HXT2.4 from Scheffersomyces stipitis lead to improved cellobiose fermentation by engineered Saccharomyces cerevisiae. Appl Environ Microbiol 2012; 79:1500-7. [PMID: 23263959 DOI: 10.1128/aem.03253-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Saccharomyces cerevisiae cannot utilize cellobiose, but this yeast can be engineered to ferment cellobiose by introducing both cellodextrin transporter (cdt-1) and intracellular β-glucosidase (gh1-1) genes from Neurospora crassa. Here, we report that an engineered S. cerevisiae strain expressing the putative hexose transporter gene HXT2.4 from Scheffersomyces stipitis and gh1-1 can also ferment cellobiose. This result suggests that HXT2.4p may function as a cellobiose transporter when HXT2.4 is overexpressed in S. cerevisiae. However, cellobiose fermentation by the engineered strain expressing HXT2.4 and gh1-1 was much slower and less efficient than that by an engineered strain that initially expressed cdt-1 and gh1-1. The rate of cellobiose fermentation by the HXT2.4-expressing strain increased drastically after serial subcultures on cellobiose. Sequencing and retransformation of the isolated plasmids from a single colony of the fast cellobiose-fermenting culture led to the identification of a mutation (A291D) in HXT2.4 that is responsible for improved cellobiose fermentation by the evolved S. cerevisiae strain. Substitutions for alanine (A291) of negatively charged amino acids (A291E and A291D) or positively charged amino acids (A291K and A291R) significantly improved cellobiose fermentation. The mutant HXT2.4(A291D) exhibited 1.5-fold higher K(m) and 4-fold higher V(max) values than those from wild-type HXT2.4, whereas the expression levels were the same. These results suggest that the kinetic properties of wild-type HXT2.4 expressed in S. cerevisiae are suboptimal, and mutations of A291 into bulky charged amino acids might transform HXT2.4p into an efficient transporter, enabling rapid cellobiose fermentation by engineered S. cerevisiae strains.
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Fungal β-glucosidase expression in Saccharomyces cerevisiae. ACTA ACUST UNITED AC 2012; 39:1445-52. [DOI: 10.1007/s10295-012-1150-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Accepted: 05/22/2012] [Indexed: 10/28/2022]
Abstract
Abstract
Recombinant Saccharomyces cerevisiae strains expressing β-glucosidases from Thermoascus aurantiacus (Tabgl1) and Phanerochaete chrysosporium (PcbglB and Pccbgl1) were constructed and compared to S. cerevisiae Y294[SFI], previously identified as the best β-glucosidase-producing strain. The PcbglB was also intracellularly expressed in combination with the lac12 lactose permease of Kluyveromyces lactis in S. cerevisiae Y294[PcbglB + Lac12]. The recombinant extracellular β-glucosidases indicated maximum activity in the pH range 4–5 and temperature optima varying from 50 to 75 °C. The S. cerevisiae Y294[Pccbgl1] strain performed best under aerobic and anaerobic conditions, producing 2.6 times more β-glucosidase activity than S. cerevisiae Y294[SFI] and an ethanol concentration of 4.8 g l−1 after 24 h of cultivation on cellobiose as sole carbohydrate source. S. cerevisiae Y294[Tabgl1] was unable to grow on cellobiose (liquid medium), whereas S. cerevisiae Y294[PcbglB + Lac12] exhibited limited growth.
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44
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Consolidated bioprocessing and simultaneous saccharification and fermentation of lignocellulose to ethanol with thermotolerant yeast strains. Process Biochem 2012. [DOI: 10.1016/j.procbio.2012.05.004] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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45
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Yang J, Dang H, Lu JR. Improving genetic immobilization of a cellulase on yeast cell surface for bioethanol production using cellulose. J Basic Microbiol 2012; 53:381-9. [DOI: 10.1002/jobm.201100602] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 03/03/2012] [Indexed: 11/08/2022]
Affiliation(s)
- Jinying Yang
- State Key Laboratory of Heavy Oil Processing & Centre for Bioengineering and Biotechnology; China University of Petroleum (East China); Qingdao; China
| | - Hongyue Dang
- State Key Laboratory of Heavy Oil Processing & Centre for Bioengineering and Biotechnology; China University of Petroleum (East China); Qingdao; China
| | - Jian Ren Lu
- Biological Physics Laboratory; School of Physics and Astronomy, University of Manchester; Manchester; UK
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Gong Z, Wang Q, Shen H, Hu C, Jin G, Zhao ZK. Co-fermentation of cellobiose and xylose by Lipomyces starkeyi for lipid production. BIORESOURCE TECHNOLOGY 2012; 117:20-4. [PMID: 22609709 DOI: 10.1016/j.biortech.2012.04.063] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 03/21/2012] [Accepted: 04/18/2012] [Indexed: 05/05/2023]
Abstract
Hydrolysates of lignocellulosic biomass contain glucose, xylose, arabinose, cellobiose, among other sugars. Effective utilization of these sugars remains challenging for microbial conversion, because most microorganisms consume such sugars sequentially with a strong preference for glucose. In the present study, the oleaginous yeast, Lipomyces starkeyi, was shown to consume cellobiose and xylose simultaneously and to produce intracellular lipids from cellobiose, xylose and glucose. In flask cultures with glucose, cellobiose or a mixture of cellobiose/xylose as carbon sources, overall substrate consumption rates were close to 0.6 g/L/h, and lipid coefficients were 0.19 g lipid/g sugar, respectively. This cellobiose/xylose co-fermentation strategy provides an opportunity to efficiently utilize lignocellulosic biomass for microbial lipid production, which is important for biorefinery and biofuel production.
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Affiliation(s)
- Zhiwei Gong
- Dalian Institute of Chemical Physics, CAS, 457 Zhongshan Road, Dalian 116023, PR China
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47
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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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48
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Codon-optimized glucoamylase sGAI of Aspergillus awamori improves starch utilization in an industrial yeast. Appl Microbiol Biotechnol 2012; 95:957-68. [PMID: 22450569 DOI: 10.1007/s00253-012-4001-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 02/29/2012] [Accepted: 02/29/2012] [Indexed: 10/28/2022]
Abstract
The development of a yeast that converts raw starch to ethanol in one step (called consolidated bioprocessing) could yield large cost reductions in the bioethanol industry. The aim of this study was to develop an efficient amylolytic Saccharomyces cerevisiae strain suitable for industrial bioethanol production. A native and codon-optimized variant of the Aspergillus awamori glucoamylase gene were expressed in the S. cerevisiae Y294 laboratory strain. Codon optimization resulted to be effective and the synthetic sequence sGAI was then δ-integrated into a S. cerevisiae strain with promising industrial fermentative traits. The mitotically stable recombinant strains showed high enzymatic capabilities both on soluble and raw starch (2425 and 1140 nkat/g dry cell weight, respectively). On raw corn starch, the engineered yeasts exhibited improved fermentative performance with an ethanol yield of 0.42 (g/g), corresponding to 75 % of the theoretical maximum yield.
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Wilde C, Gold ND, Bawa N, Tambor JHM, Mougharbel L, Storms R, Martin VJJ. Expression of a library of fungal β-glucosidases in Saccharomyces cerevisiae for the development of a biomass fermenting strain. Appl Microbiol Biotechnol 2012; 95:647-59. [DOI: 10.1007/s00253-011-3788-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 11/21/2011] [Accepted: 11/23/2011] [Indexed: 10/14/2022]
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Hasunuma T, Kondo A. Development of yeast cell factories for consolidated bioprocessing of lignocellulose to bioethanol through cell surface engineering. Biotechnol Adv 2011; 30:1207-18. [PMID: 22085593 DOI: 10.1016/j.biotechadv.2011.10.011] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 10/12/2011] [Accepted: 10/30/2011] [Indexed: 10/15/2022]
Abstract
To build an energy and material secure future, a next generation of renewable fuels produced from lignocellulosic biomass is required. Although lignocellulosic biomass, which represents an abundant, inexpensive and renewable source for bioethanol production, is of great interest as a feedstock, the complicated ethanol production processes involved make the cost of producing bioethanol from it higher compared to corn starch and cane juice. Therefore, consolidated bioprocessing (CBP), which combines enzyme production, saccharification and fermentation in a single step, has gained increased recognition as a potential bioethanol production system. CBP requires a highly engineered microorganism developed for several different process-specific characteristics. The dominant strategy for engineering a CBP biocatalyst is to express multiple components of a cellulolytic system from either fungi or bacteria in the yeast Saccharomyces cerevisiae. The development of recombinant yeast strains displaying cellulases and hemicellulases on the cell surface represents significant progress toward realization of CBP. Regardless of the process used for biomass hydrolysis, CBP-enabling microorganisms encounter a variety of toxic compounds produced during biomass pretreatment that inhibit microbial growth and ethanol yield. Systems biology approaches including disruptome screening, transcriptomics, and metabolomics have been recently exploited to gain insight into the molecular and genetic traits involved in tolerance and adaptation to the fermentation inhibitors. In this review, we focus on recent advances in development of yeast strains with both the ability to directly convert lignocellulosic material to ethanol and tolerance in the harsh environments containing toxic compounds in the presence of ethanol.
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Affiliation(s)
- Tomohisa Hasunuma
- Organization of Advanced Science and Technology, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
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