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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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Myburgh MW, van Zyl WH, Modesti M, Viljoen-Bloom M, Favaro L. Enzymatic hydrolysis of single-use bioplastic items by improved recombinant yeast strains. BIORESOURCE TECHNOLOGY 2023; 390:129908. [PMID: 37866766 DOI: 10.1016/j.biortech.2023.129908] [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: 09/06/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 10/24/2023]
Abstract
Single-use bioplastic items pose new challenges for a circular plastics economy as they require different processing than petroleum-based plastics items. Microbial and enzymatic recycling approaches could address some of the pitfalls created by the influx of bioplastic waste. In this study, the recombinant expression of a cutinase-like-enzyme (CLE1) was improved in the yeast Saccharomyces cerevisiae to efficiently hydrolyse several commercial single-use bioplastic items constituting blends of poly(lactic acid), poly(1,4-butylene adipate-co-terephthalate), poly(butylene succinate) and mineral fillers. The hydrolysis process was optimised in controlled bioreactor configurations to deliver substantial monomer concentrations and, ultimately, 29 to 78% weight loss. Product inhibition studies and molecular docking provided insights into potential bottlenecks of the enzymatic hydrolysis process, while FT-IR analysis showed the preferential breakdown of specific polymers in blended commercial bioplastic items. This work constitutes a step towards implementing enzymatic hydrolysis as a circular economy approach for the valorisation of end-of-life single-use bioplastic items.
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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), Waste to Bioproducts-Lab, 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
| | - Michele Modesti
- DII, Department of Industrial Engineering, University of Padova. Via Gradenigo 6, 35131 Padova, Italy
| | - Marinda Viljoen-Bloom
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - Lorenzo Favaro
- Department of Agronomy Food Natural resources Animals and Environment (DAFNAE), Waste to Bioproducts-Lab, Padova University, Agripolis, Viale dell'Università 16, 35020 Legnaro, Padova, Italy.
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Mafa MS, Malgas S. Towards an understanding of the enzymatic degradation of complex plant mannan structures. World J Microbiol Biotechnol 2023; 39:302. [PMID: 37688610 PMCID: PMC10492685 DOI: 10.1007/s11274-023-03753-7] [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: 07/06/2023] [Accepted: 09/04/2023] [Indexed: 09/11/2023]
Abstract
Plant cell walls are composed of a heterogeneous mixture of polysaccharides that require several different enzymes to degrade. These enzymes are important for a variety of biotechnological processes, from biofuel production to food processing. Several classical mannanolytic enzyme functions of glycoside hydrolases (GH), such as β-mannanase, β-mannosidase and α-galactosidase activities, are helpful for efficient mannan hydrolysis. In this light, we bring three enzymes into the model of mannan degradation that have received little or no attention. By linking their three-dimensional structures and substrate specificities, we have predicted the interactions and cooperativity of these novel enzymes with classical mannanolytic enzymes for efficient mannan hydrolysis. The novel exo-β-1,4-mannobiohydrolases are indispensable for the production of mannobiose from the terminal ends of mannans, this product being the preferred product for short-chain mannooligosaccharides (MOS)-specific β-mannosidases. Second, the side-chain cleaving enzymes, acetyl mannan esterases (AcME), remove acetyl decorations on mannan that would have hindered backbone cleaving enzymes, while the backbone cleaving enzymes liberate MOS, which are preferred substrates of the debranching and sidechain cleaving enzymes. The nonhydrolytic expansins and swollenins disrupt the crystalline regions of the biomass, improving their accessibility for AcME and GH activities. Finally, lytic polysaccharide monooxygenases have also been implicated in promoting the degradation of lignocellulosic biomass or mannan degradation by classical mannanolytic enzymes, possibly by disrupting adsorbed mannan residues. Modelling effective enzymatic mannan degradation has implications for improving the saccharification of biomass for the synthesis of value-added and upcycling of lignocellulosic wastes.
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Affiliation(s)
- Mpho Stephen Mafa
- Carbohydrates and Enzymology Laboratory (CHEM-LAB), Department of Plant Sciences, University of the Free State, Bloemfontein, 9300 South Africa
| | - Samkelo Malgas
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Hatfield, 0028 South Africa
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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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Steyn A, Viljoen-Bloom M, Van Zyl WH. Constructing recombinant Saccharomyces cerevisiae strains for malic-to-fumaric acid conversion. FEMS Microbiol Lett 2023; 370:6988173. [PMID: 36646426 PMCID: PMC10086307 DOI: 10.1093/femsle/fnad003] [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: 09/15/2022] [Revised: 12/09/2022] [Accepted: 01/13/2023] [Indexed: 01/18/2023] Open
Abstract
Saccharomyces cerevisiae with its robustness and good acid tolerance, is an attractive candidate for use in various industries, including waste-based biorefineries where a high-value organic acid is produced, such as fumaric acid could be beneficial. However, this yeast is not a natural producer of dicarboxylic acids, and genetic engineering of S. cerevisiae strains is required to achieve this outcome. Disruption of the natural FUM1 gene and the recombinant expression of fumarase and malate transporter genes improved the malic acid-to-fumaric acid conversion by engineered S. cerevisiae strains. The efficacy of the strains was significantly influenced by the source of the fumarase gene (yeast versus bacterial), the presence of the XYNSEC signal secretion signal and the available oxygen in synthetic media cultivations. The ΔFUM1Ckr_fum + mae1 and ΔFUM1(ss)Ckr_fum + mae1 strains converted extracellular malic acid into 0.98 and 1.11 g/L fumaric acid under aerobic conditions.
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Affiliation(s)
- Annica Steyn
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Marinda Viljoen-Bloom
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Willem Heber Van Zyl
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
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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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Liu Y, Zhu Y, Wang H, Wan L, Zhang W, Mu W. Strategies for Enhancing Microbial Production of 2'-Fucosyllactose, the Most Abundant Human Milk Oligosaccharide. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:11481-11499. [PMID: 36094047 DOI: 10.1021/acs.jafc.2c04539] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Human milk oligosaccharides (HMOs), a group of structurally diverse unconjugated glycans in breast milk, act as important prebiotics and have plenty of unique health effects for growing infants. 2'-Fucosyllactose (2'-FL) is the most abundant HMO, accounting for approximately 30%, among approximately 200 identified HMOs with different structures. 2'-FL can be enzymatically produced by α1,2-fucosyltransferase, using GDP-l-fucose as donor and lactose as acceptor. Metabolic engineering strategies have been widely used for enhancement of GDP-l-fucose supply and microbial production of 2'-FL with high productivity. GDP-l-fucose supply can be enhanced by two main pathways, including de novo and salvage pathways. 2'-FL-producing α1,2-fucosyltransferases have widely been identified from various microorganisms. Metabolic pathways for 2'-FL synthesis can be basically constructed by enhancing GDP-l-fucose supply and introducing α1,2-fucosyltransferase. Various strategies have been attempted to enhance 2'-FL production, such as acceptor enhancement, donor enhancement, and improvement of the functional expression of α1,2-fucosyltransferase. In this review, current progress in GDP-l-fucose synthesis and bacterial α1,2-fucosyltransferases is described in detail, various metabolic engineering strategies for enhancing 2'-FL production are comprehensively reviewed, and future research focuses in biotechnological production of 2'-FL are suggested.
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Affiliation(s)
- Yuanlin Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, People's Republic of China
| | - Yingying Zhu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, People's Republic of China
| | - Hao Wang
- Bloomage Biotechnology Corp., Ltd., Jinan, Shandong 250010, People's Republic of China
| | - Li Wan
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, People's Republic of China
| | - Wenli Zhang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, People's Republic of China
| | - Wanmeng Mu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, People's Republic of China
- International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, Jiangsu 214122, People's Republic of China
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Wang B, Yang C, Jiang X, Wen Y, Tian Y, Zhao C, Xu H. Design of new glycosyl-O-fipronil conjugates with improved hydrolysis efficiency assisted by molecular simulations. PEST MANAGEMENT SCIENCE 2022; 78:2667-2678. [PMID: 35365912 DOI: 10.1002/ps.6898] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 02/28/2022] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND In a previous study, we showed that two glycosyl-pesticide conjugates with a β-d-glucoside moiety, N-{3-cyano-1-[2,6-dichloro-4-(trifluoromethyl) phenyl]-4-[(trifluoromethyl)-sulfinyl]-1H-pyrazol-5-yl}-2-aminoethyl-β-d-glucopyranoside (GOF) and N-{3-cyano-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl) sulfinyl]-1H-pyrazol-5-yl}-1-(2-triazolethyl-β-d-glucopyranoside)-1H-1,2,3-triazole-4-methanamine (GOTF), can move in the phloem and be hydrolyzed by β-glucosidase at different rates. Simulations were carried out to investigate differences in the hydrolysis process in GOF, GOTF and p-nitrophenyl β-d-glucopyranoside (pNPG). A new series of glycosyl-O-fipronil conjugates was then designed and synthesized based on the simulation results. The phloem mobilities of the new conjugates were examined using a Ricinus model, and their hydrolysis efficiencies based on β-glucosidase were determined. RESULTS New glycosyl-O-fipronil conjugates GOE2-6 were designed and synthesized. To reduce steric hindrance, the conjugating site of the glycone moiety was moved to the 4'-sulfonyl group on the pyrrole ring. As a result, the hydrolysis efficiencies of the new conjugates were significantly improved, with GOE4 having the highest hydrolysis efficiency. All five conjugates could be transported in Ricinus phloem sap, consistent with previously studied glycosyl-O-fipronil conjugates. The insecticidal activities of the conjugates were tested against Plutella xylostella. CONCLUSION A strategy for the development of new phloem-mobile pesticides was proposed: linking a glycosyl group to the existing pesticide structure with a linear alkyl connection approximately four carbons in length. The resultant conjugates feature not only good phloem mobility, but also potential high bioactivity due to the efficient release of active pesticide components under the action of glucosidase. © 2022 Society of Chemical Industry.
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Affiliation(s)
| | | | - Xunyuan Jiang
- Institute of Quality Standard and Monitoring Technology for Agro-products, Guangdong Academy of Agricultural Sciences and Guangdong Provincial Key Laboratory of Quality & Safety Risk Assessment for Agro-products, Guangzhou, People's Republic of China
| | - Yingjie Wen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Key Laboratory of Natural Pesticide and Chemical Biology (Ministry of Education), South China Agricultural University, Guangzhou, People's Republic of China
| | - Yongqing Tian
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Key Laboratory of Natural Pesticide and Chemical Biology (Ministry of Education), South China Agricultural University, Guangzhou, People's Republic of China
| | - Chen Zhao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Key Laboratory of Natural Pesticide and Chemical Biology (Ministry of Education), South China Agricultural University, Guangzhou, People's Republic of China
| | - Hanhong Xu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Key Laboratory of Natural Pesticide and Chemical Biology (Ministry of Education), South China Agricultural University, Guangzhou, People's Republic of China
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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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Myburgh MW, Rose SH, Viljoen-Bloom M. Evaluating and engineering Saccharomyces cerevisiae promoters for increased amylase expression and bioethanol production from raw starch. FEMS Yeast Res 2021; 20:5891427. [PMID: 32785598 DOI: 10.1093/femsyr/foaa047] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/10/2020] [Indexed: 02/06/2023] Open
Abstract
Bioethanol production from starchy biomass via consolidated bioprocessing (CBP) will benefit from amylolytic Saccharomyces cerevisiae strains that produce high levels of recombinant amylases. This could be achieved by using strong promoters and modification thereof to improve gene expression under industrial conditions. This study evaluated eight endogenous S. cerevisiae promoters for the expression of a starch-hydrolysing α-amylase gene. A total of six of the native promoters were modified to contain a promoter-proximal intron directly downstream of the full-length promoter. Varying results were obtained; four native promoters outperformed the ENO1P benchmark under aerobic conditions and two promoters showed better expression under simulated CBP conditions. The addition of the RPS25A intron significantly improved the expression from most promoters, displaying increased transcript levels, protein concentrations and amylase activities. Raw starch-utilising strains were constructed through co-expression of selected α-amylase cassettes and a glucoamylase gene. The amylolytic strains displayed improved fermentation vigour on raw corn starch and broken rice, reaching 97% of the theoretical ethanol yield and converting 100% of the available carbon to products within 120 h in small-scale CBP fermentations on broken rice. This study showed that enhanced amylolytic strains for the conversion of raw starch to ethanol can be achieved through turnkey promoter selection and/or engineering.
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Affiliation(s)
- Marthinus W Myburgh
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - Shaunita H Rose
- 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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Lee WH, Jin YS. Observation of Cellodextrin Accumulation Resulted from Non-Conventional Secretion of Intracellular β-Glucosidase by Engineered Saccharomyces cerevisiae Fermenting Cellobiose. J Microbiol Biotechnol 2021; 31:1035-1043. [PMID: 34226403 PMCID: PMC9705985 DOI: 10.4014/jmb.2105.05018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 06/30/2021] [Accepted: 07/05/2021] [Indexed: 12/15/2022]
Abstract
Although engineered Saccharomyces cerevisiae fermenting cellobiose is useful for the production of biofuels from cellulosic biomass, cellodextrin accumulation is one of the main problems reducing ethanol yield and productivity in cellobiose fermentation with S. cerevisiae expressing cellodextrin transporter (CDT) and intracellular β-glucosidase (GH1-1). In this study, we investigated the reason for the cellodextrin accumulation and how to alleviate its formation during cellobiose fermentation using engineered S. cerevisiae fermenting cellobiose. From the series of cellobiose fermentation using S. cerevisiae expressing only GH1-1 under several culture conditions, it was discovered that small amounts of GH1-1 were secreted and cellodextrin was generated through trans-glycosylation activity of the secreted GH1-1. As GH1-1 does not have a secretion signal peptide, non-conventional protein secretion might facilitate the secretion of GH1-1. In cellobiose fermentations with S. cerevisiae expressing only GH1-1, knockout of TLG2 gene involved in non-conventional protein secretion pathway significantly delayed cellodextrin formation by reducing the secretion of GH1-1 by more than 50%. However, in cellobiose fermentations with S. cerevisiae expressing both GH1-1 and CDT-1, TLG2 knockout did not show a significant effect on cellodextrin formation, although secretion of GH1-1 was reduced by more than 40%. These results suggest that the development of new intracellular β-glucosidase, not influenced by non-conventional protein secretion, is required for better cellobiose fermentation performances of engineered S. cerevisiae fermenting cellobiose.
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Affiliation(s)
- Won-Heong Lee
- Department of Food Science and Human Nutrition, and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA,Department of Bioenergy Science and Technology, and Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, Republic of Korea,Corresponding author Phone: +82-62-530-2046 Fax: +82-62-530-2047 E-mail:
| | - Yong-Su Jin
- Department of Food Science and Human Nutrition, and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Oh EJ, Jin YS. Engineering of Saccharomyces cerevisiae for efficient fermentation of cellulose. FEMS Yeast Res 2021; 20:5698803. [PMID: 31917414 DOI: 10.1093/femsyr/foz089] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 01/08/2020] [Indexed: 12/18/2022] Open
Abstract
Conversion of lignocellulosic biomass to biofuels using microbial fermentation is an attractive option to substitute petroleum-based production economically and sustainably. The substantial efforts to design yeast strains for biomass hydrolysis have led to industrially applicable biological routes. Saccharomyces cerevisiae is a robust microbial platform widely used in biofuel production, based on its amenability to systems and synthetic biology tools. The critical challenges for the efficient microbial conversion of lignocellulosic biomass by engineered S. cerevisiae include heterologous expression of cellulolytic enzymes, co-fermentation of hexose and pentose sugars, and robustness against various stresses. Scientists developed many engineering strategies for cellulolytic S. cerevisiae strains, bringing the application of consolidated bioprocess at an industrial scale. Recent advances in the development and implementation of engineered yeast strains capable of assimilating lignocellulose will be reviewed.
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Affiliation(s)
- Eun Joong Oh
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, 4001 Discovery Dr., CO 80303, USA
| | - Yong-Su Jin
- Department of Food Science and Human Nutrition, 905 S. Goodwin Ave., IL 61801, USA.,1105 Carl R. Woese Institute for Genomic Biology, 1206 W. Gregory Dr. Urbana, IL 61801. USA.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, 1206 W. Gregory Dr. Urbana, IL 61801, USA
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13
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Enzymatic Hydrolysis of Softwood Derived Paper Sludge by an In Vitro Recombinant Cellulase Cocktail for the Production of Fermentable Sugars. Catalysts 2020. [DOI: 10.3390/catal10070775] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Paper sludge is an attractive biomass feedstock for bioconversion to ethanol due to its low cost and the lack of pretreatment required for its bioprocessing. This study assessed the use of a recombinant cellulase cocktail (mono-components: S. cerevisiae-derived PcBGL1B (BGL), TeCel7A (CBHI), ClCel6A (CBHII) and TrCel5A (EGII) mono-component cellulase enzymes) for the efficient saccharification of softwood-derived paper sludge to produce fermentable sugars. The paper sludge mainly contained 74.3% moisture and 89.7% (per dry mass (DM)) glucan with a crystallinity index of 91.5%. The optimal protein ratio for paper sludge hydrolysis was observed at 9.4: 30.2: 30.2: 30.2% for BGL: CBHI: CBHII: EGII. At a protein loading of 7.5 mg/g DW paper sludge, the yield from hydrolysis was approximately 80%, based on glucan, with scanning electron microscopy micrographs indicating a significant alteration in the microfibril size (length reduced from ≥ 2 mm to 93 µm) of the paper sludge. The paper sludge hydrolysis potential of the Opt CelMix (formulated cellulase cocktail) was similar to the commercial Cellic CTec2® and Celluclast® 1.5 L cellulase preparations and better than Viscozyme® L. Low enzyme loadings (15 mg/g paper sludge) of the Opt CelMix and solid loadings ranging between 1 to 10% (w/v) rendered over 80% glucan conversion. The high glucose yields attained on the paper sludge by the low enzyme loading of the Opt CelMix demonstrated the value of enzyme cocktail optimisation on specific substrates for efficient cellulose conversion to fermentable sugars.
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14
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Improved cellulase expression in diploid yeast strains enhanced consolidated bioprocessing of pretreated corn residues. Enzyme Microb Technol 2019; 131:109382. [DOI: 10.1016/j.enzmictec.2019.109382] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 06/27/2019] [Accepted: 07/12/2019] [Indexed: 01/12/2023]
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15
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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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16
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Sakwa L, Cripwell RA, Rose SH, Viljoen-Bloom M. Consolidated bioprocessing of raw starch with Saccharomyces cerevisiae strains expressing fungal alpha-amylase and glucoamylase combinations. FEMS Yeast Res 2019; 18:5061630. [PMID: 30085077 DOI: 10.1093/femsyr/foy085] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 07/27/2018] [Indexed: 01/10/2023] Open
Abstract
Cost-effective consolidated bioprocessing (CBP) of raw starch for biofuel production requires recombinant Saccharomyces cerevisiae strains expressing α-amylases and glucoamylases. Native Aureobasidium pullulans apuA, Aspergillus terreus ateA, Cryptococcus sp. S-2 cryA and Saccharomycopsis fibuligera sfiA genes encoding raw-starch α-amylases were cloned and expressed in the S. cerevisiae Y294 laboratory strain. Recombinant S. cerevisiae Y294[ApuA] and Y294[AteA] strains produced the highest extracellular α-amylase activities (2.17 U mL-1 and 2.98 U mL-1, respectively). Both the ApuA and AteA α-amylases displayed a preference for pH 4 to 5 and retained more than 75% activity after 5 days at 30°C. When ateA was co-expressed with the previously reported Aspergillus. tubingensis glucoamylase gene (glaA), the amylolytic S. cerevisiae Y294[AteA-GlaA] strain produced 45.77 g L-1 ethanol after 6 days. Ethanol production by this strain was improved with the addition of either 2.83 μL STARGEN 002 (54.54 g L-1 ethanol and 70.44% carbon conversion) or 20 μL commercial glucoamylase from Sigma-Aldrich (73.80 g L-1 ethanol and 90.19% carbon conversion). This is the first report of an engineered yeast strain that can replace up to 90% of the enzymes required for raw starch hydrolysis, and thus contributes to the realisation of a CBP yeast for starch-based biofuel production.
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Affiliation(s)
- L Sakwa
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - R A Cripwell
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - S H Rose
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - M Viljoen-Bloom
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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17
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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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18
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Verma ML, Kumar S, Das A, Randhawa JS, Chamundeeswari M. Enzyme Immobilization on Chitin and Chitosan-Based Supports for Biotechnological Applications. SUSTAINABLE AGRICULTURE REVIEWS 35 2019. [DOI: 10.1007/978-3-030-16538-3_4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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19
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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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20
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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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21
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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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22
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Lemos WJ, Bovo B, Nadai C, Crosato G, Carlot M, Favaron F, Giacomini A, Corich V. Biocontrol Ability and Action Mechanism of Starmerella bacillaris (Synonym Candida zemplinina) Isolated from Wine Musts against Gray Mold Disease Agent Botrytis cinerea on Grape and Their Effects on Alcoholic Fermentation. Front Microbiol 2016; 7:1249. [PMID: 27574517 PMCID: PMC4983571 DOI: 10.3389/fmicb.2016.01249] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 07/27/2016] [Indexed: 12/11/2022] Open
Abstract
Gray mold is one of the most important diseases of grapevine in temperate climates. This plant pathogen affects plant growth and reduces wine quality. The use of yeasts as biocontrol agents to apply in the vineyard have been investigated in recent years as an alternative to agrochemicals. In this work, fermenting musts obtained from overripe grape berries, therefore more susceptible to infection by fungal pathogens such as Botrytis cinerea, were considered for the selection of yeasts carrying antifungal activity. Thirty-six isolates were identified as Starmerella bacillaris, a species recently proven to be of enological interest. Among them 14 different strains were studied and antifungal activity against B. cinerea was demonstrated, for the first time, to be present in S. bacillaris species. The production of volatile organic compounds (VOCs), tested in vitro, was found to be the main responsible of S. bacillaris antifungal effects. All the strains were able to reduce B. cinerea decay on wounded grape berries artificially inoculated with gray mold. The colonization level of wound was very high reaching, after 5 days, a concentration of 106 cells per ml of grape juice obtained after berry crushing. At this cell concentration S. bacillaris strains were used to ferment synthetic and natural musts. The sequential yeast inoculation, performed by adding S. cerevisiae 48 h after S. bacillaris, was needed to complete sugar consumption and determined a significant increase in glicerol content and a reduction of ethanol and acetic acid concentrations. The high wound colonization ability, found in this work, together with the propensity to colonize grape berry and the interesting enological traits possessed by the selected S. bacillaris strains allow the use of this yeast as biocontrol agent on vine and grape berries with possible positive effects on must fermentation, although the presence of S. cerevisiae is needed to complete the fermentation process. This work introduces new possibilities in wine yeast selection programs in order to identify innovative wine yeasts that are simultaneously antifungal agents in vineyards and alternative wine starters for grape must fermentation and open new perspective to a more integrated strategy for increasing wine quality.
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Affiliation(s)
- Wilson J Lemos
- Department of Agronomy Food Natural Resources Animals and Environment, University of Padova Legnaro, Italy
| | - Barbara Bovo
- Department of Agronomy Food Natural Resources Animals and Environment, University of PadovaLegnaro, Italy; Interdepartmental Centre for Research in Viticulture and Enology, University of PadovaConegliano, Italy
| | - Chiara Nadai
- Department of Agronomy Food Natural Resources Animals and Environment, University of PadovaLegnaro, Italy; Interdepartmental Centre for Research in Viticulture and Enology, University of PadovaConegliano, Italy
| | - Giulia Crosato
- Department of Agronomy Food Natural Resources Animals and Environment, University of PadovaLegnaro, Italy; Interdepartmental Centre for Research in Viticulture and Enology, University of PadovaConegliano, Italy
| | - Milena Carlot
- Department of Agronomy Food Natural Resources Animals and Environment, University of PadovaLegnaro, Italy; Interdepartmental Centre for Research in Viticulture and Enology, University of PadovaConegliano, Italy
| | - Francesco Favaron
- Department of Land Environment Agriculture and Forestry, University of Padova Legnaro, Italy
| | - Alessio Giacomini
- Department of Agronomy Food Natural Resources Animals and Environment, University of PadovaLegnaro, Italy; Interdepartmental Centre for Research in Viticulture and Enology, University of PadovaConegliano, Italy
| | - Viviana Corich
- Department of Agronomy Food Natural Resources Animals and Environment, University of PadovaLegnaro, Italy; Interdepartmental Centre for Research in Viticulture and Enology, University of PadovaConegliano, Italy
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23
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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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24
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Behera SS, Ray RC. Solid state fermentation for production of microbial cellulases: Recent advances and improvement strategies. Int J Biol Macromol 2016; 86:656-69. [DOI: 10.1016/j.ijbiomac.2015.10.090] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 10/28/2015] [Accepted: 10/29/2015] [Indexed: 12/23/2022]
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25
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Molecular cloning and expression of thermostable glucose-tolerant β-glucosidase of Penicillium funiculosum NCL1 in Pichia pastoris and its characterization. ACTA ACUST UNITED AC 2015; 42:553-65. [DOI: 10.1007/s10295-014-1549-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 11/14/2014] [Indexed: 11/26/2022]
Abstract
Abstract
A partial peptide sequence of β-glucosidase isoform (Bgl4) of Penicillium funiculosum NCL1 was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The cDNA (bgl4) encoding Bgl4 protein was cloned from P. funiculosum NCL1 RNA by consensus RT-PCR. The bgl4 gene encoded 857 amino acids that contained catalytic domains specific for glycoside hydrolase family 3. The cDNA was over-expressed in Pichia pastoris KM71H and the recombinant protein (rBgl4) was purified with the specific activity of 1,354.3 U/mg. The rBgl4 was a glycoprotein with the molecular weight of ~130 kDa and showed optimal activity at pH 5.0 and 60 °C. The enzyme was thermo-tolerant up to 60 °C for 60 min. The rBgl4 was highly active on aryl substrates with β-glucosidic, β-xylosidic linkages and moderately active on cellobiose and salicin. It showed remarkably high substrate conversion rate of 3,332 and 2,083 μmol/min/mg with the substrates p-nitrophenyl β-glucoside and cellobiose respectively. In addition, the rBgl4 showed tolerance to glucose concentration up to 400 mM. It exhibited twofold increase in glucose yield when supplemented with crude cellulase of Trichoderma reesei Rut-C30 in cellulose hydrolysis. These results suggested that rBgl4 is a thermo- and glucose-tolerant β-glucosidase and is a potential supplement for commercial cellulase in cellulose hydrolysis and thereby assures profitability in bioethanol production.
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26
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Malherbe AR, Rose SH, Viljoen-Bloom M, van Zyl WH. Expression and evaluation of enzymes required for the hydrolysis of galactomannan. J Ind Microbiol Biotechnol 2014; 41:1201-9. [PMID: 24888762 DOI: 10.1007/s10295-014-1459-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 05/08/2014] [Indexed: 11/25/2022]
Abstract
The cost-effective production of bioethanol from lignocellulose requires the complete conversion of plant biomass, which contains up to 30 % mannan. To ensure utilisation of galactomannan during consolidated bioprocessing, heterologous production of mannan-degrading enzymes in fungal hosts was explored. The Aspergillus aculeatus endo-β-mannanase (Man1) and Talaromyces emersonii α-galactosidase (Agal) genes were expressed in Saccharomyces cerevisiae Y294, and the Aspergillus niger β-mannosidase (cMndA) and synthetic Cellvibrio mixtus β-mannosidase (Man5A) genes in A. niger. Maximum enzyme activity for Man1 (374 nkat ml(-1), pH 5.47), Agal (135 nkat ml(-1), pH 2.37), cMndA (12 nkat ml(-1), pH 3.40) and Man5A (8 nkat ml(-1), pH 3.40) was observed between 60 and 70 °C. Co-expression of the Man1 and Agal genes in S. cerevisiae Y294[Agal-Man1] reduced the extracellular activity relative to individual expression of the respective genes. However, the combined action of crude Man1, Agal and Man5A enzyme preparations significantly decreased the viscosity of galactomannan in locust bean gum, confirming hydrolysis thereof. Furthermore, when complemented with exogenous Man5A, S. cerevisiae Y294[Agal-Man1] produced 56 % of the theoretical ethanol yield, corresponding to a 66 % carbohydrate conversion, on 5 g l(-1) mannose and 10 g l(-1) locust bean gum.
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Affiliation(s)
- A R Malherbe
- Department of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
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27
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Mendoza-Aguayo DJ, Poggi-Varaldo HM, García-Mena J, Ramos-Valdivia AC, Salgado LM, de la Torre-Martínez M, Ponce-Noyola T. Extracellular expression of glucose inhibition-resistant Cellulomonas flavigena PN-120 β-glucosidase by a diploid strain of Saccharomyces cerevisiae. Arch Microbiol 2013; 196:25-33. [PMID: 24217872 DOI: 10.1007/s00203-013-0935-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/16/2013] [Accepted: 10/23/2013] [Indexed: 11/30/2022]
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