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Marciano CL, de Almeida AP, Bezerra FC, Giannesi GC, Cabral H, Teixeira de Moraes Polizeli MDL, Ruller R, Masui DC. Enhanced saccharification levels of corn starch using as a strategy a novel amylolytic complex (AmyHb) from the thermophilic fungus Humicola brevis var. thermoidea in association with commercial enzyme. 3 Biotech 2024; 14:198. [PMID: 39131173 PMCID: PMC11310185 DOI: 10.1007/s13205-024-04038-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 07/30/2024] [Indexed: 08/13/2024] Open
Abstract
Amylases represent a versatile group of catalysts that are used for the saccharification of starch because they can hydrolyze the glycosidic bonds of starch molecules to release glucose, maltose, and short-chain oligosaccharides. The amylolytic complex of the thermophilic filamentous fungus Humicola brevis var. thermoidea (AmyHb) was produced, biochemically characterized, and compared with the commercial amylase Termamyl. In addition, the biotechnological application of AmyHb in starch saccharification was investigated. The highest production was achieved using a wheat bran medium at 50 °C for 5-6 days in solid-state fermentation (849.6 ± 18.2 U·g-1) without the addition of inducers. Optimum amylolytic activity occurred at pH 5.0 at 60 °C, and stability was maintained between pH 5.0 and 6.0, with thermal stability at 50-60 °C, especially in the presence of Ca2+. These results were superior to those found with Termamyl. Both enzymes were strongly inhibited by Hg2+, Cu2+, and Ag+; however, AmyHb displayed increased activity in the presence of Mn2+ and Na+. In addition, AmyHb showed greater tolerance to a wide range of ethanol concentrations. AmyHb appears to be a complex consisting of glucoamylase and α-amylase, based on its substrate specificity and TLC. The hydrolysis tests on cornstarch flour showed that the cocktail of AmyHb50% + Termamyl50% significantly increased the release of glucose and total reducing sugars (36.6%) when compared to the enzymes alone. AmyHb exhibited promising physicochemical properties and good performance with commercial amylase; therefore, this complex is a biotechnological alternative candidate for the bioprocessing of starch sources.
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Affiliation(s)
- Camila Langer Marciano
- Laboratório de Bioquímica Geral E de Microrganismos-LBQ, Instituto de Biociências-INBIO, Universidade Federal de Mato Grosso Do Sul-UFMS, Campo Grande, MS CEP: 79070-900 Brazil
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, FCFRP – Universidade de São Paulo, Ribeirão Preto, SP CEP: 14040-903 Brazil
| | - Aline Pereira de Almeida
- Faculdade de Medicina de Ribeirão Preto, FMRP – Universidade de São Paulo, Ribeirão Preto, SP CEP: 14049-900 Brazil
- Departamento de Biologia, Faculdade de Filosofia, Ciências E Letras de Ribeirão Preto - FFCLRP, Universidade de São Paulo-USP, Ribeirão Preto, SP CEP: 14040-901 Brazil
| | - Fabiane Cruz Bezerra
- Laboratório de Bioquímica Geral E de Microrganismos-LBQ, Instituto de Biociências-INBIO, Universidade Federal de Mato Grosso Do Sul-UFMS, Campo Grande, MS CEP: 79070-900 Brazil
| | - Giovana Cristina Giannesi
- Laboratório de Bioquímica Geral E de Microrganismos-LBQ, Instituto de Biociências-INBIO, Universidade Federal de Mato Grosso Do Sul-UFMS, Campo Grande, MS CEP: 79070-900 Brazil
| | - Hamilton Cabral
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, FCFRP – Universidade de São Paulo, Ribeirão Preto, SP CEP: 14040-903 Brazil
| | | | - Roberto Ruller
- Departamento de Biologia, Faculdade de Filosofia, Ciências E Letras de Ribeirão Preto - FFCLRP, Universidade de São Paulo-USP, Ribeirão Preto, SP CEP: 14040-901 Brazil
- Universidade Estadual Paulista - UNESP, Instituto de Biociências, Letras e Ciências Exatas - IBILCE, São José do Rio Preto, SP CEP: 15054-000 Brazil
- Centro de Ciências Naturais e Humanas - CCNH, Universidade Federal do ABC - UFABC, Santo André, SP CEP: 09210-170 Brazil
| | - Douglas Chodi Masui
- Laboratório de Bioquímica Geral E de Microrganismos-LBQ, Instituto de Biociências-INBIO, Universidade Federal de Mato Grosso Do Sul-UFMS, Campo Grande, MS CEP: 79070-900 Brazil
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Benites-Pariente JS, Samolski I, Ludeña Y, Villena GK. CRISPR/Cas9 mediated targeted knock-in of eglA gene to improve endoglucanase activity of Aspergillus fumigatus LMB-35Aa. Sci Rep 2024; 14:19661. [PMID: 39179646 PMCID: PMC11344075 DOI: 10.1038/s41598-024-70397-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Accepted: 08/16/2024] [Indexed: 08/26/2024] Open
Abstract
Bioeconomy goals for using biomass feedstock for biofuels and bio-based production has arisen the demand for fungal strains and enzymes for biomass processing. Despite well-known Trichoderma and Aspergillus commercial strains, continuous bioprospecting has revealed the fungal biodiversity potential for production of biomass degrading enzymes. The strain Aspergillus fumigatus LMB-35Aa has revealed a great potential as source of lignocellulose-degrading enzymes. Nevertheless, genetic improvement should be considered to increase its biotechnological potential. Molecular manipulation based on homologous direct recombination (HDR) in filamentous fungi poses a challenge since its low recombination rate. Currently, CRISPR/Cas9-mediated mutagenesis can enable precise and efficient editing of filamentous fungi genomes. In this study, a CRISPR/Cas9-mediated gene editing strategy for improving endoglucanase activity of A. fumigatus LMB-35Aa strain was successfully used, which constitutes the first report of heterologous cellulase production in filamentous fungi using this technology. For this, eglA gene from A. niger ATCC 10,864 was integrated into conidial melanin pksP gene locus, which facilitated the selection of edited events discerned by the emergence of albino colonies. Heterologous production of the EglA enzyme in a biofilm fermentation system resulted in a 40% improvement in endoglucanase activity of the mutant strain compared to the wild type.
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Affiliation(s)
- J S Benites-Pariente
- Laboratorio de Micología y Biotecnología "Marcel Gutiérrez-Correa", Universidad Nacional Agraria la Molina, 15024, Lima, Peru
| | - I Samolski
- Laboratorio de Micología y Biotecnología "Marcel Gutiérrez-Correa", Universidad Nacional Agraria la Molina, 15024, Lima, Peru
| | - Y Ludeña
- Laboratorio de Micología y Biotecnología "Marcel Gutiérrez-Correa", Universidad Nacional Agraria la Molina, 15024, Lima, Peru
| | - G K Villena
- Laboratorio de Micología y Biotecnología "Marcel Gutiérrez-Correa", Universidad Nacional Agraria la Molina, 15024, Lima, Peru.
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Cripwell RA, My R, Treu L, Campanaro S, Favaro L, van Zyl WH, Viljoen-Bloom M. Additional glucoamylase genes increase ethanol productivity on rice and potato waste streams by a recombinant amylolytic yeast. BIORESOURCE TECHNOLOGY 2023; 388:129787. [PMID: 37741578 DOI: 10.1016/j.biortech.2023.129787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 09/25/2023]
Abstract
The implementation of consolidated bioprocessing for converting starch to ethanol relies on a robust yeast that produces enough amylases for rapid starch hydrolysis. Furthermore, using low-cost substrates will assist with competitive ethanol prices and support a bioeconomy, especially in developing countries. This paper addresses both challenges with the expression of additional glucoamylase gene copies in an efficient amylolytic strain (Saccharomyces cerevisiae ER T12) derived from the industrial yeast, Ethanol Red™. Recombinant ER T12 was used as a host to increase ethanol productivity during raw starch fermentation; the ER T12.7 variant, selected from various transformants, displayed enhanced raw starch conversion and a 36% higher ethanol concentration than the parental strain after 120 h. Unripe rice, rice bran, potato waste and potato peels were evaluated as alternative starchy substrates to test ER T12.7's fermenting ability. ER T12.7 produced high ethanol yields at significantly improved ethanol productivity, key criteria for its industrial application.
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Affiliation(s)
- Rosemary A Cripwell
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - Rebecca My
- Waste to Bioproducts-Lab, Department of Agronomy Food Natural resources Animals and Environment (DAFNAE), Università di Padova, Agripolis, Viale dell'Università 16, 35020 Legnaro, Padova, Italy
| | - Laura Treu
- Department of Biology, University of Padova, Via U. Bassi 58/b, 35121, Padova, Italy
| | - Stefano Campanaro
- Department of Biology, University of Padova, Via U. Bassi 58/b, 35121, Padova, Italy
| | - Lorenzo Favaro
- Waste to Bioproducts-Lab, Department of Agronomy Food Natural resources Animals and Environment (DAFNAE), Università di Padova, 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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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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5
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Wu Y, Feng S, Sun Z, Hu Y, Jia X, Zeng B. An outlook to sophisticated technologies and novel developments for metabolic regulation in the Saccharomyces cerevisiae expression system. Front Bioeng Biotechnol 2023; 11:1249841. [PMID: 37869712 PMCID: PMC10586203 DOI: 10.3389/fbioe.2023.1249841] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 09/04/2023] [Indexed: 10/24/2023] Open
Abstract
Saccharomyces cerevisiae is one of the most extensively used biosynthetic systems for the production of diverse bioproducts, especially biotherapeutics and recombinant proteins. Because the expression and insertion of foreign genes are always impaired by the endogenous factors of Saccharomyces cerevisiae and nonproductive procedures, various technologies have been developed to enhance the strength and efficiency of transcription and facilitate gene editing procedures. Thus, the limitations that block heterologous protein secretion have been overcome. Highly efficient promoters responsible for the initiation of transcription and the accurate regulation of expression have been developed that can be precisely regulated with synthetic promoters and double promoter expression systems. Appropriate codon optimization and harmonization for adaption to the genomic codon abundance of S. cerevisiae are expected to further improve the transcription and translation efficiency. Efficient and accurate translocation can be achieved by fusing a specifically designed signal peptide to an upstream foreign gene to facilitate the secretion of newly synthesized proteins. In addition to the widely applied promoter engineering technology and the clear mechanism of the endoplasmic reticulum secretory pathway, the innovative genome editing technique CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated system) and its derivative tools allow for more precise and efficient gene disruption, site-directed mutation, and foreign gene insertion. This review focuses on sophisticated engineering techniques and emerging genetic technologies developed for the accurate metabolic regulation of the S. cerevisiae expression system.
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Affiliation(s)
| | | | | | | | | | - Bin Zeng
- College of Pharmacy, Shenzhen Technology University, Shenzhen, Guangdong, China
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6
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Smuts IE, Blakeway NJ, Rose SH, den Haan R, Viljoen-Bloom M, van Zyl WH. Supplementation of recombinant cellulases with LPMOs and CDHs improves consolidated bioprocessing of cellulose. Enzyme Microb Technol 2023; 164:110171. [PMID: 36549094 DOI: 10.1016/j.enzmictec.2022.110171] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/15/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022]
Abstract
The increased demand for energy has sparked a global search for renewable energy sources that could partly replace fossil fuel resources and help mitigate climate change. Cellulosic biomass is an ideal feedstock for renewable bioethanol production, but the process is not currently economically feasible due to the high cost of pretreatment and enzyme cocktails to release fermentable sugars. Lytic polysaccharide monooxygenases (LPMOs) and cellobiose dehydrogenases (CDHs) are auxiliary enzymes that can enhance cellulose hydrolysis. In this study, four LPMO and two CDH genes were subcloned and expressed in the Saccharomyces cerevisiae Y294 laboratory strain. SDS-PAGE analysis confirmed the extracellular production of the LPMOs and CDHs in the laboratory S. cerevisiae Y294 strain. A rudimentary cellulase cocktail (cellobiohydrolase 1 and 2, endoglucanase and β-glucosidase) was expressed in the commercial CelluX™ 4 strain and extracellular production of the individual cellulases was confirmed by SDS-PAGE analysis. In vitro cooperation of the CDHs and LPMOs with the rudimentary cellulases produced by strain CelluX™ 4[F4-1] was demonstrated on Whatman filter paper. The significant levels of soluble sugars released from this crystalline cellulose substrate indicated that these auxiliary enzymes could be important components of the CBP yeast cellulolytic system.
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Affiliation(s)
- Ivy E Smuts
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Nicole J Blakeway
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Shaunita H Rose
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Riaan den Haan
- Department of Biotechnology, University of the Western Cape, Bellville 7530, South Africa
| | - Marinda Viljoen-Bloom
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Willem H van Zyl
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa.
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7
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Schwerdtfeger KS, Myburgh MW, van Zyl WH, Viljoen-Bloom M. Promoter-proximal introns impact recombinant amylase expression in Saccharomyces cerevisiae. FEMS Yeast Res 2023; 23:foad047. [PMID: 37891015 PMCID: PMC10647015 DOI: 10.1093/femsyr/foad047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 09/29/2023] [Accepted: 10/26/2023] [Indexed: 10/29/2023] Open
Abstract
Consolidated bioprocessing (CBP) of starch requires recombinant Saccharomyces cerevisiae strains that produce raw starch-degrading enzymes and ferment the resultant sugars to ethanol in a single step. In this study, the native S. cerevisiae COX4 and RPS25A promoter-proximal introns were evaluated for enhanced expression of amylase genes (ateA, temA or temG_Opt) under the control of an S. cerevisiae promoter (ENO1P, TEF1P, TDH3P, or HXT7P). The results showed that different promoters and promoter-intron combinations differentially affected recombinant amylase production: ENO1P-COX4i and TDH3P-RPS25Ai were the best promoters for AteA, followed closely by HXT7P. The latter was also the best promoter for TemA and TemG production, followed closely by TDH3P-RPS25Ai for both these enzymes. Introducing promoter-proximal introns increased amylase activity up to 62% in Y294[ENO-COX-AteA] and Y294[TDH3-RPS-TemA], a significant improvement relative to the intron-less promoters. Strains co-expressing both an α-amylase and glucoamylase genes yielded up to 56 g/L ethanol from 20% w/v raw starch, with a higher carbon conversion observed with strains co-expressing TDH3P-RPS25Ai-temG_Opt than HXT7P-temG_Opt. The study showed that promoter-proximal introns can enhance amylase activity in S. cerevisiae and suggest that these alternative cassettes may also be considered for expression in more efficient ethanol-producing industrial yeast strains for raw starch CBP.
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Affiliation(s)
- Kirstie S Schwerdtfeger
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - Marthinus W Myburgh
- Department of Microbiology, 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
| | - Marinda Viljoen-Bloom
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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Expression of a Salt-Tolerant Pseudolysin in Yeast for Efficient Protein Hydrolysis under High-Salt Conditions. Biomolecules 2022; 13:biom13010083. [PMID: 36671468 PMCID: PMC9855795 DOI: 10.3390/biom13010083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/30/2022] [Accepted: 12/27/2022] [Indexed: 01/03/2023] Open
Abstract
Protease biocatalysis in a high-salt environment is very attractive for applications in the detergent industry, the production of diagnostic kits, and traditional food fermentation. However, high-salt conditions can reduce protease activity or even inactivate enzymes. Herein, in order to explore new protease sources, we expressed a salt-tolerant pseudolysin of Pseudomonas aeruginosa SWJSS3 isolated from deep-sea mud in Saccharomyces cerevisiae. After optimizing the concentration of ion cofactors in yeast peptone dextrose (YPD) medium, the proteolytic activity in the supernatant was 2.41 times more than that in the control group when supplemented with 5 mM CaCl2 and 0.4 mM ZnCl2. The extracellular proteolytic activity of pseudolysin reached 258.95 U/mL with optimized expression cassettes. In addition, the S. cerevisiae expression system increased the salt tolerance of pseudolysin to sodium chloride (NaCl)and sodium dodecyl sulfate (SDS) and the recombinant pseudolysin retained 15.19% activity when stored in 3 M NaCl for 7 days. The recombinant pseudolysin was able to efficiently degrade the β-conglycinin from low-denatured soy protein isolates and glycinin from high-denatured soy protein isolates under high temperatures (60 °C) and high-salt (3 M NaCl) conditions. Our study provides a salt-tolerant recombinant protease with promising applications in protein hydrolysis under high-salt conditions.
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Li J, Zeng Y, Wang WB, Wan QQ, Liu CG, den Haan R, van Zyl WH, Zhao XQ. Increasing extracellular cellulase activity of the recombinant Saccharomyces cerevisiae by engineering cell wall-related proteins for improved consolidated processing of carbon neutral lignocellulosic biomass. BIORESOURCE TECHNOLOGY 2022; 365:128132. [PMID: 36252752 DOI: 10.1016/j.biortech.2022.128132] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/09/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Sustainable bioproduction usingcarbon neutral feedstocks, especially lignocellulosic biomass, has attracted increasing attention due to concern over climate change and carbon reduction. Consolidated bioprocessing (CBP) of lignocellulosic biomass using recombinantyeast of Saccharomyces cerevisiaeis a promising strategy forlignocellulosic biorefinery. However, the economic viability is restricted by low enzyme secretion levels.For more efficient CBP, MIG1spsc01isolated from the industrial yeast which encodes the glucose repression regulator derivative was overexpressed. Increased extracellular cellobiohydrolase (CBH) activity was observed with unexpectedly decreased cell wall integrity. Further studies revealed that disruption ofCWP2, YGP1, andUTH1,which are functionally related toMIG1spsc01, also enhanced CBH secretion. Subsequently, improved cellulase production was achieved by simultaneous disruption ofYGP1and overexpression ofSED5, which remarkably increased extracellular CBH activity of 2.2-fold over the control strain. These results provide a novel strategy to improve the CBP yeast for bioconversion of carbon neutral biomass.
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Affiliation(s)
- Jie Li
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yu Zeng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wei-Bin Wang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qing-Qing Wan
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chen-Guang Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Riaan den Haan
- Department of Biotechnology, University of the Western Cape, Bellville 7530, South Africa
| | - Willem H van Zyl
- Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa
| | - Xin-Qing Zhao
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
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10
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Chetty BJ, Inokuma K, Hasunuma T, van Zyl WH, den Haan R. Improvement of cell-tethered cellulase activity in recombinant strains of Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2022; 106:6347-6361. [PMID: 35951080 DOI: 10.1007/s00253-022-12114-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 07/27/2022] [Accepted: 07/28/2022] [Indexed: 11/30/2022]
Abstract
Consolidated bioprocessing (CBP) remains an attractive option for the production of commodity products from pretreated lignocellulose if a process-suitable organism can be engineered. The yeast Saccharomyces cerevisiae requires engineered cellulolytic activity to enable its use in CBP production of second-generation (2G) bioethanol. A promising strategy for heterologous cellulase production in yeast entails displaying enzymes on the cell surface by means of glycosylphosphatidylinositol (GPI) anchors. While strains producing a core set of cell-adhered cellulases that enabled crystalline cellulose hydrolysis have been created, secreted levels of enzyme were insufficient for complete cellulose hydrolysis. In fact, all reported recombinant yeast CBP candidates must overcome the drawback of generally low secretion titers. Rational strain engineering can be applied to enhance the secretion phenotype. This study aimed to improve the amount of cell-adhered cellulase activities of recombinant S. cerevisiae strains expressing a core set of four cellulases, through overexpression of genes that were previously shown to enhance cellulase secretion. Results showed significant increases in cellulolytic activity for all cell-adhered cellulase enzyme types. Cell-adhered cellobiohydrolase activity was improved by up to 101%, β-glucosidase activity by up to 99%, and endoglucanase activity by up to 231%. Improved hydrolysis of crystalline cellulose of up to 186% and improved ethanol yields from this substrate of 40-50% in different strain backgrounds were also observed. In addition, improvement in resistance to fermentation stressors was noted in some strains. These strains represent a step towards more efficient organisms for use in 2G biofuel production. KEY POINTS: • Cell-surface-adhered cellulase activity was improved in strains engineered for CBP. • Levels of improvement of activity were strain and enzyme dependent. • Crystalline cellulose conversion to ethanol could be improved up to 50%.
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Affiliation(s)
- Bronwyn Jean Chetty
- Department of Biotechnology, University of the Western Cape, Bellville, South Africa
| | - Kentaro Inokuma
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
| | - Tomohisa Hasunuma
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, 657-8501, Japan
| | | | - Riaan den Haan
- Department of Biotechnology, University of the Western Cape, Bellville, South Africa.
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11
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van Aalst AC, de Valk SC, van Gulik WM, Jansen ML, Pronk JT, Mans R. Pathway engineering strategies for improved product yield in yeast-based industrial ethanol production. Synth Syst Biotechnol 2022; 7:554-566. [PMID: 35128088 PMCID: PMC8792080 DOI: 10.1016/j.synbio.2021.12.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 12/16/2022] Open
Abstract
Product yield on carbohydrate feedstocks is a key performance indicator for industrial ethanol production with the yeast Saccharomyces cerevisiae. This paper reviews pathway engineering strategies for improving ethanol yield on glucose and/or sucrose in anaerobic cultures of this yeast by altering the ratio of ethanol production, yeast growth and glycerol formation. Particular attention is paid to strategies aimed at altering energy coupling of alcoholic fermentation and to strategies for altering redox-cofactor coupling in carbon and nitrogen metabolism that aim to reduce or eliminate the role of glycerol formation in anaerobic redox metabolism. In addition to providing an overview of scientific advances we discuss context dependency, theoretical impact and potential for industrial application of different proposed and developed strategies.
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Affiliation(s)
- Aafke C.A. van Aalst
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629, HZ Delft, the Netherlands
| | - Sophie C. de Valk
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629, HZ Delft, the Netherlands
| | - Walter M. van Gulik
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629, HZ Delft, the Netherlands
| | - Mickel L.A. Jansen
- DSM Biotechnology Centre, Alexander Fleminglaan 1, 2613, AX Delft, the Netherlands
| | - Jack T. Pronk
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629, HZ Delft, the Netherlands
| | - Robert Mans
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629, HZ Delft, the Netherlands
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Hettinga K, Bijl E. Can recombinant milk proteins replace those produced by animals? Curr Opin Biotechnol 2022; 75:102690. [PMID: 35104717 DOI: 10.1016/j.copbio.2022.102690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 12/13/2021] [Accepted: 01/15/2022] [Indexed: 11/03/2022]
Abstract
The consumption of animal proteins in general, and dairy proteins in particular, is associated with sustainability and animal welfare issues. Recombinant synthesis of milk proteins is therefore receiving increasing interest, with several studies showing synthesis of milk proteins using a wide range of expression systems. Achieving a high yield and purity is essential for economic production. Besides the synthesis, also the construction of the specific structure in which milk proteins are present in animal milks, casein micelles, is needed. Looking at the current state-of-the-art, the steps to produce recombinant dairy products are technically feasible, but whether it can be implemented at low cost, with the process being environmentally friendly, remains to be seen in the coming years.
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Affiliation(s)
- Kasper Hettinga
- Dairy Science & Technology, Food Quality and Design Group, Wageningen University & Research, 6708WG Wageningen, The Netherlands.
| | - Etske Bijl
- Dairy Science & Technology, Food Quality and Design Group, Wageningen University & Research, 6708WG Wageningen, The Netherlands
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Gronchi N, De Bernardini N, Cripwell RA, Treu L, Campanaro S, Basaglia M, Foulquié-Moreno MR, Thevelein JM, Van Zyl WH, Favaro L, Casella S. Natural Saccharomyces cerevisiae Strain Reveals Peculiar Genomic Traits for Starch-to-Bioethanol Production: the Design of an Amylolytic Consolidated Bioprocessing Yeast. Front Microbiol 2022; 12:768562. [PMID: 35126325 PMCID: PMC8815085 DOI: 10.3389/fmicb.2021.768562] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 12/17/2021] [Indexed: 11/13/2022] Open
Abstract
Natural yeast with superior fermentative traits can serve as a platform for the development of recombinant strains that can be used to improve the sustainability of bioethanol production from starch. This process will benefit from a consolidated bioprocessing (CBP) approach where an engineered strain producing amylases directly converts starch into ethanol. The yeast Saccharomyces cerevisiae L20, previously selected as outperforming the benchmark yeast Ethanol Red, was here subjected to a comparative genomic investigation using a dataset of industrial S. cerevisiae strains. Along with Ethanol Red, strain L20 was then engineered for the expression of α-amylase amyA and glucoamylase glaA genes from Aspergillus tubingensis by employing two different approaches (delta integration and CRISPR/Cas9). A correlation between the number of integrated copies and the hydrolytic abilities of the recombinants was investigated. L20 demonstrated important traits for the construction of a proficient CBP yeast. Despite showing a close relatedness to commercial wine yeast and the benchmark Ethanol Red, a unique profile of gene copy number variations (CNVs) was found in L20, mainly encoding membrane transporters and secretion pathway proteins but also the fermentative metabolism. Moreover, the genome annotation disclosed seven open reading frames (ORFs) in L20 that are absent in the reference S288C genome. Genome engineering was successfully implemented for amylase production. However, with equal amylase gene copies, L20 proved its proficiency as a good enzyme secretor by exhibiting a markedly higher amylolytic activity than Ethanol Red, in compliance to the findings of the genomic exploration. The recombinant L20 dT8 exhibited the highest amylolytic activity and produced more than 4 g/L of ethanol from 2% starch in a CBP setting without the addition of supplementary enzymes. Based on the performance of this strain, an amylase/glucoamylase ratio of 1:2.5 was suggested as baseline for further improvement of the CBP ability. Overall, L20 showed important traits for the future construction of a proficient CBP yeast. As such, this work shows that natural S. cerevisiae strains can be used for the expression of foreign secreted enzymes, paving the way to strain improvement for the starch-to-bioethanol route.
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Affiliation(s)
- Nicoletta Gronchi
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, Legnaro, Italy
| | | | - Rosemary A Cripwell
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Laura Treu
- Department of Biology, University of Padua, Padua, Italy
| | | | - Marina Basaglia
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, Legnaro, Italy
| | | | - Johan M Thevelein
- Department of Molecular Microbiology, VIB, KU Leuven, Leuven, Belgium
- NovelYeast Bv, Open Bio-Incubator, Erasmus High School, Jette, Belgium
| | - Willem H Van Zyl
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Lorenzo Favaro
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, Legnaro, Italy
| | - Sergio Casella
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, Legnaro, Italy
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