1
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Hamal EK, Alfassi G, Antonenko M, Rein DM, Cohen Y. Cellulose-coated emulsion micro-particles self-assemble with yeasts for cellulose bio-conversion. Sci Rep 2024; 14:5499. [PMID: 38448579 PMCID: PMC10918086 DOI: 10.1038/s41598-024-56204-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Accepted: 03/04/2024] [Indexed: 03/08/2024] Open
Abstract
In the quest for alternative renewable energy sources, a new self-assembled hybrid configuration of cellulose-coated oil-in-water emulsion particles with yeast was formed. In this research, the addition of yeasts (S. cerevisiae) to the micro-particle emulsion revealed a novel self-assembly configuration in which the yeast cell is connected to surrounding cellulose-coated micro-particles. This hybrid configuration may enhance the simultaneous saccharification and fermentation process by substrate channeling. Glucose produced by hydrolysis of the cellulose shells coating the micro-particles, catalyzed by cellulytic enzymes attached to their coating, is directly fermented to ethanol by the yeasts to which the particles are connected. The results indicate ethanol yield of 62%, based on the cellulose content of the emulsion, achieved by the yeast/micro-particle hybrids. The functionality of this hybrid configuration is expected to serve as a micro-reactor for a cascade of biochemical reactions in a "one-pot" consolidated process transforming cellulose to valuable chemicals, such as biodiesel.
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Affiliation(s)
- Ester Korkus Hamal
- Department of Chemical Engineering, Technion - Israel Institute of Technology, 3200003, Haifa, Israel.
| | - Gilad Alfassi
- Department of Biotechnology Engineering, Braude College of Engineering, Karmiel, Israel
| | - Margarita Antonenko
- Department of Chemical Engineering, Technion - Israel Institute of Technology, 3200003, Haifa, Israel
| | - Dmitry M Rein
- Department of Chemical Engineering, Technion - Israel Institute of Technology, 3200003, Haifa, Israel
| | - Yachin Cohen
- Department of Chemical Engineering, Technion - Israel Institute of Technology, 3200003, Haifa, Israel
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2
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Zhang C, Chen H, Zhu Y, Zhang Y, Li X, Wang F. Saccharomyces cerevisiae cell surface display technology: Strategies for improvement and applications. Front Bioeng Biotechnol 2022; 10:1056804. [PMID: 36568309 PMCID: PMC9767963 DOI: 10.3389/fbioe.2022.1056804] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 11/25/2022] [Indexed: 12/13/2022] Open
Abstract
Microbial cell surface display technology provides a powerful platform for engineering proteins/peptides with enhanced properties. Compared to the classical intracellular and extracellular expression (secretion) systems, this technology avoids enzyme purification, substrate transport processes, and is an effective solution to enzyme instability. Saccharomyces cerevisiae is well suited to cell surface display as a common cell factory for the production of various fuels and chemicals, with the advantages of large cell size, being a Generally Regarded As Safe (GRAS) organism, and post-translational processing of secreted proteins. In this review, we describe various strategies for constructing modified S. cerevisiae using cell surface display technology and outline various applications of this technology in industrial processes, such as biofuels and chemical products, environmental pollution treatment, and immunization processes. The approaches for enhancing the efficiency of cell surface display are also discussed.
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Affiliation(s)
- Chenmeng Zhang
- Jiangsu Co Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, China,Jiangsu Provincial Key Lab for Chemistry and Utilization of Agro Forest Biomass, Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, Nanjing, China,International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing, China
| | - Hongyu Chen
- Jiangsu Co Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, China,Jiangsu Provincial Key Lab for Chemistry and Utilization of Agro Forest Biomass, Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, Nanjing, China,International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing, China
| | - Yiping Zhu
- Jiangsu Co Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, China,Jiangsu Provincial Key Lab for Chemistry and Utilization of Agro Forest Biomass, Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, Nanjing, China,International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing, China
| | - Yu Zhang
- Jiangsu Co Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, China,Jiangsu Provincial Key Lab for Chemistry and Utilization of Agro Forest Biomass, Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, Nanjing, China,International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing, China
| | - Xun Li
- Jiangsu Co Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, China,Jiangsu Provincial Key Lab for Chemistry and Utilization of Agro Forest Biomass, Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, Nanjing, China,International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing, China
| | - Fei Wang
- Jiangsu Co Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, China,Jiangsu Provincial Key Lab for Chemistry and Utilization of Agro Forest Biomass, Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, Nanjing, China,International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing, China,*Correspondence: Fei Wang,
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3
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Zajki-Zechmeister K, Eibinger M, Nidetzky B. Enzyme Synergy in Transient Clusters of Endo- and Exocellulase Enables a Multilayer Mode of Processive Depolymerization of Cellulose. ACS Catal 2022; 12:10984-10994. [PMID: 36082050 PMCID: PMC9442579 DOI: 10.1021/acscatal.2c02377] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 08/12/2022] [Indexed: 11/29/2022]
Abstract
Biological degradation of cellulosic materials relies on the molecular-mechanistic principle that internally chain-cleaving endocellulases work synergistically with chain end-cleaving exocellulases in polysaccharide chain depolymerization. How endo-exo synergy becomes effective in the deconstruction of a solid substrate that presents cellulose chains assembled into crystalline material is an open question of the mechanism, with immediate implications on the bioconversion efficiency of cellulases. Here, based on single-molecule evidence from real-time atomic force microscopy, we discover that endo- and exocellulases engage in the formation of transient clusters of typically three to four enzymes at the cellulose surface. The clusters form specifically at regular domains of crystalline cellulose microfibrils that feature molecular defects in the polysaccharide chain organization. The dynamics of cluster formation correlates with substrate degradation through a multilayer-processive mode of chain depolymerization, overall leading to the directed ablation of single microfibrils from the cellulose surface. Each multilayer-processive step involves the spatiotemporally coordinated and mechanistically concerted activity of the endo- and exocellulases in close proximity. Mechanistically, the cooperativity with the endocellulase enables the exocellulase to pass through its processive cycles ∼100-fold faster than when acting alone. Our results suggest an advanced paradigm of efficient multienzymatic degradation of structurally organized polymer materials by endo-exo synergetic chain depolymerization.
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Affiliation(s)
- Krisztina Zajki-Zechmeister
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
| | - Manuel Eibinger
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
| | - Bernd Nidetzky
- Institute
of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 10-12/1, 8010 Graz, Austria
- Austrian
Centre of Industrial Biotechnology, Petersgasse 14, 8010 Graz, Austria
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4
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Qu Y, Qin Z, Zhang R, Wu D, Ji F, Shi Z, Zhao S, Liu L, Yu J. High-efficiency and recyclability of ramie degumming catalyzed by FeCl 3 in organic solvent. Carbohydr Polym 2020; 239:116250. [PMID: 32414442 DOI: 10.1016/j.carbpol.2020.116250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 03/27/2020] [Accepted: 03/31/2020] [Indexed: 11/24/2022]
Abstract
Although traditional alkaline (TAL) process for ramie degumming is commonly used in the industry, it causes severe environmental concerns. In this work, an emerging organic solvent degumming process utilizing FeCl3 catalyst (FeCl3-OS) was developed in one step. The influences of FeCl3-OS system on fiber properties (e.g. residual gum content, tenacity, degree of polymerization (DP), etc.) were evaluated, and the recyclability of degumming solution was also studied. The results indicated that ramie fiber could be isolated with FeCl3-OS treatment (FeCl3 1.0 %, 200 ℃, 121 min), and the tenacity and residual gum content of refined fibers were 7.9 cN/dtex and 3.88 %, respectively. Fibers treated in FeCl3-OS system were endowed better moisture sorption (9.2 %) and higher yield (75.2 %) compared with that in TAL system. Moreover, fibers with five cycles' treatment possessed outstanding performances, that was 4.44 cN/dtex of tenacity and 4.33 % of residual gum content, which fulfilled the requirements of the spinning process.
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Affiliation(s)
- Yongshuai Qu
- Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai, 201620, China
| | - Zhihui Qin
- Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai, 201620, China
| | - Ruiyun Zhang
- Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai, 201620, China; Innovation Center for Textile Science and Technology, Donghua University, Shanghai, 201620, China.
| | - Dequn Wu
- Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai, 201620, China; Innovation Center for Textile Science and Technology, Donghua University, Shanghai, 201620, China
| | - Feng Ji
- Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai, 201620, China
| | - Zhaohe Shi
- Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai, 201620, China
| | - Shuyuan Zhao
- Key Laboratory of Textile Science & Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai, 201620, China
| | - Liu Liu
- Innovation Center for Textile Science and Technology, Donghua University, Shanghai, 201620, China
| | - Jianyong Yu
- Innovation Center for Textile Science and Technology, Donghua University, Shanghai, 201620, China
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5
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Draft genome sequence of Parvularcula flava strain NH6-79 T, revealing its role as a cellulolytic enzymes producer. Arch Microbiol 2020; 202:2591-2597. [PMID: 32607725 DOI: 10.1007/s00203-020-01967-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 06/17/2020] [Accepted: 06/24/2020] [Indexed: 01/03/2023]
Abstract
To date, the genus Parvularcula consists of 6 species and no potential application of this genus was reported. Current study presents the genome sequence of Parvularcula flava strain NH6-79 T and its cellulolytic enzyme analysis. The assembled draft genome of strain NH6-79 T consists of 9 contigs and 7 scaffolds with 3.68 Mbp in size and GC content of 59.87%. From a total of 3,465 genes predicted, 96 of them are annotated as glycoside hydrolases (GHs). Within these GHs, 20 encoded genes are related to cellulosic biomass degradation, including 12 endoglucanases (5 GH10, 4 GH5, and 3 GH51), 2 exoglucanases (GH9) and 6 β-glucosidases (GH3). In addition, highest relative enzyme activities (endoglucanase, exoglucanase, and β-glucosidase) were observed at 27th hour when the strain was cultured in the carboxymethyl cellulose/Avicel®-containing medium for 45 h. The combination of genome analysis with experimental studies indicated the ability of strain NH6-79 T to produce extracellular endoglucanase, exoglucanase, and β-glucosidase. These findings suggest the potential of Parvularcula flava strain NH6-79 T in cellulose-containing biomass degradation and that the strain could be used in cellulosic biorefining process.
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6
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Claes A, Deparis Q, Foulquié-Moreno MR, Thevelein JM. Simultaneous secretion of seven lignocellulolytic enzymes by an industrial second-generation yeast strain enables efficient ethanol production from multiple polymeric substrates. Metab Eng 2020; 59:131-141. [DOI: 10.1016/j.ymben.2020.02.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 02/01/2020] [Accepted: 02/18/2020] [Indexed: 01/22/2023]
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7
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Partition usage of cellulose by coupling approach of supercritical carbon dioxide and cellulase to reducing sugar and nanocellulose. Carbohydr Polym 2020; 229:115533. [PMID: 31826392 DOI: 10.1016/j.carbpol.2019.115533] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 10/19/2019] [Accepted: 10/24/2019] [Indexed: 11/23/2022]
Abstract
Cellulose is the most abundant renewable resource on earth, and its economic utilization has long been a hot research topic. To address these challenges, based on the coexistence of crystalline and amorphous structures within cellulose, we coupled supercritical carbon dioxide (SC-CO2) and cellulase to utilize cellulose subregions. This approach is taken into consideration from the structure of cellulose. Cellulose amorphous regions were enzymatically hydrolysed into reducing sugar, and crystalline regions were converted to nanocellulose, representing efficient use of available raw material. This nanocellulose exhibited different properties with these derived from the traditional method. The smallest effective diameter almost was approximately 5nm, suggesting good uniformity and stability of the nanocellulose. Cellulose characterization results showed that the coupled method exposed more free hydroxyl groups which enhanced the accessibility between the cellulose and substrate, and the stability of nanocellulose. The established process was tested on cotton linters and similar results were obtained.
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8
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Faba L, Garcés D, Díaz E, Ordóñez S. Carbon Materials as Phase-Transfer Promoters for Obtaining 5-Hydroxymethylfurfural from Cellulose in a Biphasic System. CHEMSUSCHEM 2019; 12:3769-3777. [PMID: 31240829 DOI: 10.1002/cssc.201901264] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/04/2019] [Indexed: 06/09/2023]
Abstract
Different carbonaceous materials were tested as mass-transfer promoters for increasing the yield of 5-hydroxymethylfurfural (5-HMF) in biphasic cellulose hydrolysis. The benefits of working with a biphasic system (water/methyl isobutyl ketone) under soft acid conditions were taken as starting point (no humins or levulinic acid production), with slow extraction kinetics as the weakest point of this approach. Carbon nanotubes (CNTs) and activated carbon (AC) were proposed to improve 5-HMF liquid-liquid mass transfer. A kinetic analysis of the extraction process indicated the competition between 5-HMF and glucose adsorption as the main cause of the poor results obtained with AC. In contrast, very promising results were obtained with CNTs, mainly at 1.5 wt % loading, with complete transfer of HMF and a high global mass-transfer coefficient. The use of CNTs improved the amount of 5-HMF in the organic phase by more than 270 %.
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Affiliation(s)
- Laura Faba
- CRC Research Group, Department of Chemical and Environmental Engineering, University of Oviedo, c/ Julián Clavería s/n, 33006, Oviedo, Spain
| | - Diego Garcés
- CRC Research Group, Department of Chemical and Environmental Engineering, University of Oviedo, c/ Julián Clavería s/n, 33006, Oviedo, Spain
| | - Eva Díaz
- CRC Research Group, Department of Chemical and Environmental Engineering, University of Oviedo, c/ Julián Clavería s/n, 33006, Oviedo, Spain
| | - Salvador Ordóñez
- CRC Research Group, Department of Chemical and Environmental Engineering, University of Oviedo, c/ Julián Clavería s/n, 33006, Oviedo, Spain
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9
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Zhai R, Hu J, Saddler JN. Minimizing cellulase inhibition of whole slurry biomass hydrolysis through the addition of carbocation scavengers during acid-catalyzed pretreatment. BIORESOURCE TECHNOLOGY 2018; 258:12-17. [PMID: 29518686 DOI: 10.1016/j.biortech.2018.02.124] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 02/25/2018] [Accepted: 02/26/2018] [Indexed: 05/20/2023]
Abstract
The aim of this work was to study how to minimize cellulase inhibition of whole slurry biomass hydrolysis through addition of carbocation scavengers during acid-catalyzed pretreatment. Various potential carbocation scavengers were compared and their inhibition mitigating effects towards the hydrolytic performance of cellulase enzymes was assessed. The results indicated that the addition of carbocation scavengers during the pretreatment process could not only alleviate the inhibitory effect of the phenolics on the enzymatic hydrolysis but also increase the accessibility of cellulases to the pretreated substrates. It appeared that lignin-derived compounds such as 4-hydroxybenzoic acid, vanillic acid, syringic acid could all serve as efficient scavengers to alleviate the inhibitory effect of phenolics on cellulose hydrolysis where the syringic acid showed the best mitigating effect. By combining the carbocation scavengers in the pretreatment process, an improved cellulose hydrolysis of the pretreated whole slurry could be achieved without any post detoxification step.
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Affiliation(s)
- Rui Zhai
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing 210094, China; Forest Products Biotechnology and Bioenergy Group, Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada
| | - Jinguang Hu
- Forest Products Biotechnology and Bioenergy Group, Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada.
| | - Jack N Saddler
- Forest Products Biotechnology and Bioenergy Group, Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada
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10
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Hu J, Tian D, Renneckar S, Saddler JN. Enzyme mediated nanofibrillation of cellulose by the synergistic actions of an endoglucanase, lytic polysaccharide monooxygenase (LPMO) and xylanase. Sci Rep 2018; 8:3195. [PMID: 29453372 PMCID: PMC5816652 DOI: 10.1038/s41598-018-21016-6] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 01/29/2018] [Indexed: 01/26/2023] Open
Abstract
Physiochemical methods have generally been used to “open-up” biomass substrates/pulps and have been the main method used to fibrillate cellulose. However, recent work has shown that canonical cellulase enzymes such as endoglucanases, in combination with “amorphogenesis inducing” proteins such as lytic polysaccharide monooxygenases (LPMO), swollenin and hemicellulases, are able to increase cellulose accessibility. In the work reported here different combinations of endoglucanase, LPMO and xylanase were applied to Kraft pulps to assess their potential to induce fibrillation at low enzyme loading over a short time period. Although gross fiber properties (fiber length, width and morphology) were relatively unchanged, over a short period of time, the intrinsic physicochemical characteristics of the pulp fibers (e.g. cellulose accessibility/DP/crystallinity/charge) were positively enhanced by the synergistic cooperation of the enzymes. LPMO addition resulted in the oxidative cleavage of the pulps, increasing the negative charge (~100 mmol kg−1) on the cellulose fibers. This improved cellulose nanofibrilliation while stabilizing the nanofibril suspension (zeta potential ζ = ~60 mV), without sacrificing nanocellulose thermostability. The combination of endoglucanase, LPMO and xylanases was shown to facilitate nanofibrillation, potentially reducing the need for mechanical refining while resulting in a pulp with a more uniform nanofibril composition.
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Affiliation(s)
- Jinguang Hu
- Department of Wood Science, Forest Products Biotechnology/Bioenergy Group, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Dong Tian
- Department of Wood Science, Forest Products Biotechnology/Bioenergy Group, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada.,Institute of Ecological and Environmental Sciences, Sichuan Agricultural University, Chengdu, Sichuan, 611130, PR China
| | - Scott Renneckar
- Department of Wood Science, Advanced Renewable Materials Lab, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Jack N Saddler
- Department of Wood Science, Forest Products Biotechnology/Bioenergy Group, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada.
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11
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Kansou K, Rémond C, Paës G, Bonnin E, Tayeb J, Bredeweg B. Testing scientific models using Qualitative Reasoning: Application to cellulose hydrolysis. Sci Rep 2017; 7:14122. [PMID: 29074872 PMCID: PMC5658447 DOI: 10.1038/s41598-017-14281-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 10/06/2017] [Indexed: 12/17/2022] Open
Abstract
With the accumulation of scientific information in natural science, even experts can find difficult to keep integrating new piece of information. It is critical to explore modelling solutions able to capture information scattered in publications as a computable representation form. Traditional modelling techniques are important in that regard, but relying on numerical information comes with limitations for integrating results from distinct studies, high-level representations can be more suited. We present an approach to stepwise construct mechanistic explanation from selected scientific papers using the Qualitative Reasoning framework. As a proof of concept, we apply the approach to modelling papers about cellulose hydrolysis mechanism, focusing on the causal explanations for the decreasing of hydrolytic rate. Two explanatory QR models are built to capture classical explanations for the phenomenon. Our results show that none of them provides sufficient explanation for a set of basic experimental observations described in the literature. Combining the two explanations into a third one allowed to get a new and sufficient explanation for the experimental results. In domains where numerical data are scarce and strongly related to the experimental conditions, this approach can aid assessing the conceptual validity of an explanation and support integration of knowledge from different sources.
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Affiliation(s)
- Kamal Kansou
- INRA, Biopolymères Interactions Assemblages, BP 71267, 44316, Nantes, France.
| | - Caroline Rémond
- FARE laboratory, INRA, University of Reims Champagne-Ardenne, 51100, Reims, France
| | - Gabriel Paës
- FARE laboratory, INRA, University of Reims Champagne-Ardenne, 51100, Reims, France
| | - Estelle Bonnin
- INRA, Biopolymères Interactions Assemblages, BP 71267, 44316, Nantes, France
| | - Jean Tayeb
- FARE laboratory, INRA, University of Reims Champagne-Ardenne, 51100, Reims, France
| | - Bert Bredeweg
- Informatics Institute, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
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12
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Liu Z, Inokuma K, Ho SH, den Haan R, van Zyl WH, Hasunuma T, Kondo A. Improvement of ethanol production from crystalline cellulose via optimizing cellulase ratios in cellulolytic Saccharomyces cerevisiae. Biotechnol Bioeng 2017; 114:1201-1207. [PMID: 28112385 DOI: 10.1002/bit.26252] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/28/2016] [Accepted: 01/15/2017] [Indexed: 12/30/2022]
Abstract
Crystalline cellulose is one of the major contributors to the recalcitrance of lignocellulose to degradation, necessitating high dosages of cellulase to digest, thereby impeding the economic feasibility of cellulosic biofuels. Several recombinant cellulolytic yeast strains have been developed to reduce the cost of enzyme addition, but few of these strains are able to efficiently degrade crystalline cellulose due to their low cellulolytic activities. Here, by combining the cellulase ratio optimization with a novel screening strategy, we successfully improved the cellulolytic activity of a Saccharomyces cerevisiae strain displaying four different synergistic cellulases on the cell surface. The optimized strain exhibited an ethanol yield from Avicel of 57% of the theoretical maximum, and a 60% increase of ethanol titer from rice straw. To our knowledge, this work is the first optimization of the degradation of crystalline cellulose by tuning the cellulase ratio in a cellulase cell-surface display system. This work provides key insights in engineering the cellulase cocktail in a consolidated bioprocessing yeast strain. Biotechnol. Bioeng. 2017;114: 1201-1207. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Zhuo Liu
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Kentaro Inokuma
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Shih-Hsin Ho
- State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, PR 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
| | - Tomohisa Hasunuma
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Akihiko Kondo
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.,Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.,Biomass Engineering Program, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
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13
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Siqueira G, Arantes V, Saddler JN, Ferraz A, Milagres AMF. Limitation of cellulose accessibility and unproductive binding of cellulases by pretreated sugarcane bagasse lignin. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:176. [PMID: 28702081 PMCID: PMC5504807 DOI: 10.1186/s13068-017-0860-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 06/27/2017] [Indexed: 05/03/2023]
Abstract
BACKGROUND The effectiveness of the enzymatic hydrolysis of cellulose in plant cell wall is strongly influenced by the access of enzymes to cellulose, which is at least in part limited by the presence of lignin. Although physicochemical treatments preceding the enzymatic catalysis significantly overcome this recalcitrance, the residual lignin can still play a role in the process. Lignin is suggested to act as a barrier, hindering cellulose and limiting the access of the enzymes. It can also unspecifically bind cellulases, reducing the amount of enzymes available to act on cellulose. However, the limiting role of the lignin present in pretreated sugarcane bagasses has not been fully understood yet. RESULTS A set of sugarcane bagasses pretreated by five leading pretreatment technologies was created and used to assess their accessibility and the unproductive binding capacity of the resulting lignins. Steam explosion and alkaline sulfite pretreatments resulted in more accessible substrates, with approximately 90% of the cellulose hydrolyzed using high enzyme loadings. Enzymatic hydrolysis of alkaline-treated (NaOH) and steam-exploded sugarcane bagasses were strongly affected by unproductive binding at the lowest enzyme loading tested. Analysis of the extracted lignins confirmed the superior binding capacity of these lignins. Sulfite-based pretreatments (alkaline sulfite and acid sulfite) resulted in lignins with lower binding capacities compared to the analogue pretreatments without sulfite (alkaline and acidic). Strong acid groups present in sulfite-based pretreated substrates, attributed to sulfonated lignins, corroborated the lower binding capacities of the lignin present in these substrates. A more advanced enzyme preparation (Cellic CTec3) was shown to be less affected by unproductive binding at low enzyme loading. CONCLUSIONS Pretreatments that increase the accessibility and modify the lignin are necessary in order to decrease the protein binding capacity. The search for the called weak lignin-binding enzymes is of major importance if hydrolysis with low enzyme loadings is the goal for economically viable processes.
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Affiliation(s)
- Germano Siqueira
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CP 116, Lorena, SP 12602-810 Brazil
- Forest Products Biotechnology/Bioenergy Group, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4 Canada
| | - Valdeir Arantes
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CP 116, Lorena, SP 12602-810 Brazil
- Forest Products Biotechnology/Bioenergy Group, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4 Canada
| | - Jack N. Saddler
- Forest Products Biotechnology/Bioenergy Group, Faculty of Forestry, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4 Canada
| | - André Ferraz
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CP 116, Lorena, SP 12602-810 Brazil
| | - Adriane M. F. Milagres
- Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, CP 116, Lorena, SP 12602-810 Brazil
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14
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Song HT, Gao Y, Yang YM, Xiao WJ, Liu SH, Xia WC, Liu ZL, Yi L, Jiang ZB. Synergistic effect of cellulase and xylanase during hydrolysis of natural lignocellulosic substrates. BIORESOURCE TECHNOLOGY 2016; 219:710-715. [PMID: 27560367 DOI: 10.1016/j.biortech.2016.08.035] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 08/10/2016] [Accepted: 08/11/2016] [Indexed: 05/22/2023]
Abstract
Synergistic combination of cellulase and xylanase has been performed on pre-treated substrates in many previous studies, while few on natural substrates. In this study, three unpretreated lignocellulosic substrates were studied, including corncob, corn stover, and rice straw. The results indicated that when the mixed cellulase and xylanase were applied, reducing sugar concentrations were calculated as 19.53, 15.56, and 17.35mg/ml, respectively, based on the 3,5 dinitrosalicylic acid (DNS) method. Compared to the treatment with only cellulose, the hydrolysis yields caused by mixed cellulase and xylanase were improved by 133%, 164%, and 545%, respectively. In addition, the conversion yield of corncob, corn stover, and rice straw by cellulase-xylanase co-treatment reached 43.9%, 48.5%, and 40.2%, respectively, based on HPLC analysis, which confirmed the synergistic effect of cellulase-xylanase that was much higher than either of the single enzyme treatment. The substrate morphology was also evaluated to explore the synergistic mechanism of cellulase-xylanase.
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Affiliation(s)
- Hui-Ting Song
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, PR China; College of Resources and Environmental Science, Hubei University, Wuhan 430062, PR China.
| | - Yuan Gao
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, PR China.
| | - Yi-Min Yang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, PR China.
| | - Wen-Jing Xiao
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, PR China.
| | - Shi-Hui Liu
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, PR China.
| | - Wu-Cheng Xia
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, PR China.
| | - Zi-Lu Liu
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, PR China.
| | - Li Yi
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, PR China.
| | - Zheng-Bing Jiang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, PR China; Hubei Key Laboratory of Industrial Biotechnology, College of Life Science, Hubei University, Wuhan 430062, PR China.
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15
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Liu Z, Ho SH, Sasaki K, den Haan R, Inokuma K, Ogino C, van Zyl WH, Hasunuma T, Kondo A. Engineering of a novel cellulose-adherent cellulolytic Saccharomyces cerevisiae for cellulosic biofuel production. Sci Rep 2016; 6:24550. [PMID: 27079382 PMCID: PMC4832201 DOI: 10.1038/srep24550] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/26/2016] [Indexed: 11/09/2022] Open
Abstract
Cellulosic biofuel is the subject of increasing attention. The main obstacle toward its economic feasibility is the recalcitrance of lignocellulose requiring large amount of enzyme to break. Several engineered yeast strains have been developed with cellulolytic activities to reduce the need for enzyme addition, but exhibiting limited effect. Here, we report the successful engineering of a cellulose-adherent Saccharomyces cerevisiae displaying four different synergistic cellulases on the cell surface. The cellulase-displaying yeast strain exhibited clear cell-to-cellulose adhesion and a "tearing" cellulose degradation pattern; the adhesion ability correlated with enhanced surface area and roughness of the target cellulose fibers, resulting in higher hydrolysis efficiency. The engineered yeast directly produced ethanol from rice straw despite a more than 40% decrease in the required enzyme dosage for high-density fermentation. Thus, improved cell-to-cellulose interactions provided a novel strategy for increasing cellulose hydrolysis, suggesting a mechanism for promoting the feasibility of cellulosic biofuel production.
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Affiliation(s)
- Zhuo Liu
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Shih-Hsin Ho
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.,State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, PR China
| | - Kengo Sasaki
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Riaan den Haan
- Department of Biotechnology, University of the Western Cape, Bellville 7530, South Africa
| | - Kentaro Inokuma
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Chiaki Ogino
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Willem H van Zyl
- Department of Microbiology, University of Stellenbosch, Stellenbosch 7600, South Africa
| | - Tomohisa Hasunuma
- Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan
| | - Akihiko Kondo
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.,Biomass Engineering Program, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
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16
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Liu Z, Inokuma K, Ho SH, Haan RD, Hasunuma T, van Zyl WH, Kondo A. Combined cell-surface display- and secretion-based strategies for production of cellulosic ethanol with Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:162. [PMID: 26413161 PMCID: PMC4584016 DOI: 10.1186/s13068-015-0344-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/18/2015] [Indexed: 05/12/2023]
Abstract
BACKGROUND Engineering Saccharomyces cerevisiae to produce heterologous cellulases is considered as a promising strategy for production of bioethanol from lignocellulose. The production of cellulase is usually pursued by one of the two strategies: displaying enzyme on the cell surface or secreting enzyme into the medium. However, to our knowledge, the combination of the two strategies in a yeast strain has not been employed. RESULTS In this study, heterologous endoglucanase (EG) and cellobiohydrolase I (CBHI) were produced in a β-glucosidase displaying S. cerevisiae strain using cell-surface display, secretion, or a combined strategy. Strains EG-D-CBHI-D and EG-S-CBHI-S (with both enzymes displayed on the cell surface or with both enzymes secreted to the surrounding medium) showed higher ethanol production (2.9 and 2.6 g/L from 10 g/L phosphoric acid swollen cellulose, respectively), than strains EG-D-CBHI-S and EG-S-CBHI-D (with EG displayed on cell surface and CBHI secreted, or vice versa). After 3-cycle repeated-batch fermentation, the cellulose degradation ability of strain EG-D-CBHI-D remained 60 % of the 1st batch, at a level that was 1.7-fold higher than that of strain EG-S-CBHI-S. CONCLUSIONS This work demonstrated that placing EG and CBHI in the same space (on the cell surface or in the medium) was favorable for amorphous cellulose-based ethanol fermentation. In addition, the cellulolytic yeast strain that produced enzymes by the cell-surface display strategy performed better in cell-recycle batch fermentation compared to strains producing enzymes via the secretion strategy.
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Affiliation(s)
- Zhuo Liu
- />Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
| | - Kentaro Inokuma
- />Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
| | - Shih-Hsin Ho
- />Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
- />State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, 150090 People’s Republic of China
| | - Riaan den Haan
- />Department of Biotechnology, University of the Western Cape, Bellville, 7530 South Africa
| | - Tomohisa Hasunuma
- />Organization of Advanced Science and Technology, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
| | - Willem H. van Zyl
- />Department of Microbiology, University of Stellenbosch, Stellenbosch, 7600 South Africa
| | - Akihiko Kondo
- />Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe, 657-8501 Japan
- />Biomass Engineering Program, RIKEN, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045 Japan
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