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Duan S, Wu Y, Chao T, Zhang N, Wei Z, Ji R. Improving the catalytic activity and thermostability of Aspergillus niger xylanase through computational design. Protein Expr Purif 2024; 223:106561. [PMID: 39094812 DOI: 10.1016/j.pep.2024.106561] [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: 07/21/2024] [Revised: 07/26/2024] [Accepted: 07/30/2024] [Indexed: 08/04/2024]
Abstract
Xylanase plays the most important role in catalyzing xylan to xylose moieties. GH11 xylanases have been widely used in many fields, but most GH11 xylanases are mesophilic enzymes. To improve the catalytic activity and thermostability of Aspergillus niger xylanase (Xyn-WT), we predicted potential key mutation sites of Xyn-WT through multiple computer-aided enzyme engineering strategies. We introduce a simple and economical Ni affinity chromatography purification method to obtain high-purity xylanase and its mutants. Ten mutants (Xyn-A, Xyn-B, Xyn-C, E45T, Q93R, E45T/Q93R, A161P, Xyn-D, Xyn-E, Xyn-F) were identified. Among the ten mutants, four (Xyn-A, Xyn-C, A161P, Xyn-F) presented improved thermal stability and activity, with Xyn-F(A161P/E45T/Q93R) being the most thermally stable and active. Compared with Xyn-WT, after heat treatment at 55 °C and 60 °C for 10 min, the remaining enzyme activity of Xyn-F was 12 and 6 times greater than that of Xyn-WT, respectively, and Xyn-F was approximately 1.5 times greater than Xyn-WT when not heat treated. The pH adaptation of Xyn-F was also significantly enhanced. In summary, an improved catalytic activity and thermostability of the design variant Xyn-F has been reported.
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Affiliation(s)
- Shuyan Duan
- College of Food Science and Pharmaceutical Engineering, Zaozhuang University, Zaozhuang, Shandong, 277160, China.
| | - Yaoyao Wu
- College of Food Science and Pharmaceutical Engineering, Zaozhuang University, Zaozhuang, Shandong, 277160, China
| | - Tianzhu Chao
- College of Food Science and Pharmaceutical Engineering, Zaozhuang University, Zaozhuang, Shandong, 277160, China
| | - Nan Zhang
- College of Food Science and Pharmaceutical Engineering, Zaozhuang University, Zaozhuang, Shandong, 277160, China
| | - Zhaoyi Wei
- College of Food Science and Pharmaceutical Engineering, Zaozhuang University, Zaozhuang, Shandong, 277160, China
| | - Rui Ji
- Shandong Academy of Pharmaceutical Sciences, Key Laboratory of Biopharmaceuticals, Jinan, 250101, China.
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2
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Liang S, Wang X, Sun S, Xie L, Dang X. Extraction of chitin from flammulina velutipes waste: A low-concentration acid pretreatment and aspergillus Niger fermentation approach. Int J Biol Macromol 2024; 273:133224. [PMID: 38897518 DOI: 10.1016/j.ijbiomac.2024.133224] [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: 12/16/2023] [Revised: 06/03/2024] [Accepted: 06/15/2024] [Indexed: 06/21/2024]
Abstract
In recent years, with the booming of the edible mushroom industry, chitin production has become increasingly dependent on fungi and other non-traditional sources. Fungal chitin has advantages including superior performance, simpler separation processes, abundant raw materials, and the absence of shellfish allergens. As a kind of edible mushroom, flammulina velutipes (F. velutipes) also has the advantages of wide source and large annual yield. This provided the possibility for the extraction of chitin. Here, a procedure to extract chitin from F. velutipes waste be presented. This method comprises low-concentration acid pretreatment coupled with consolidated bioprocessing with Aspergillus niger. Characterization by SEM, FTIR, XRD, NMR, and TGA confirmed that the extracted chitin was β-chitin. To achieve optimal fermentation of F. velutipes waste (80 g/L), ammonium sulfate and glucose were selected as nitrogen and carbon sources (5 g/L), with a fermentation time of 5 days. The extracted chitin could be further deacetylated and purified to obtain high-purity chitosan (99.2 % ± 1.07 %). This chitosan exhibited a wide degree of deacetylation (50.0 % ± 1.33 % - 92.1 % ± 0.97 %) and a molecular weight distribution of 92-192 kDa. Notably, the yield of chitosan extracted in this study was increased by 56.3 % ± 0.47 % compared to the traditional chemical extraction method.
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Affiliation(s)
- Shuang Liang
- Institute of Biomass and Function Materials & National Demonstration Centre for Experimental Light Chemistry Engineering Education, College of Bioresources Chemistry and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, PR China
| | - Xuechuan Wang
- Institute of Biomass and Function Materials & National Demonstration Centre for Experimental Light Chemistry Engineering Education, College of Bioresources Chemistry and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, PR China.
| | - Siwei Sun
- Institute of Basic and Translational Medicine, Xi'an Medical University, Xi'an, Shaanxi 710021, PR China
| | - Long Xie
- College of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi 710021, PR China
| | - Xugang Dang
- Institute of Biomass and Function Materials & National Demonstration Centre for Experimental Light Chemistry Engineering Education, College of Bioresources Chemistry and Materials Engineering, Shaanxi University of Science and Technology, Xi'an 710021, PR China; Hubei Provincial Engineering Laboratory for Clean Production and High-Value Utilization of Bio-Based Textile Materials, Wuhan Textile University, Wuhan 430200, PR China.
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3
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Ma XY, Coleman B, Prabhu P, Yang M, Wen F. Engineering Compositionally Uniform Yeast Whole-Cell Biocatalysts with Maximized Surface Enzyme Density for Cellulosic Biofuel Production. ACS Synth Biol 2024; 13:1225-1236. [PMID: 38551819 DOI: 10.1021/acssynbio.3c00669] [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] [Indexed: 04/20/2024]
Abstract
In recent decades, whole-cell biocatalysis has played an increasingly important role in the food, pharmaceutical, and energy sector. One promising application is the use of ethanologenic yeast displaying minicellulosomes on the cell surface to combine cellulose hydrolysis and fermentation into a single step for consolidated bioprocessing. However, cellulosic ethanol production using existing yeast whole-cell biocatalysts (yWCBs) has not reached industrial feasibility due to their inefficient cellulose hydrolysis. As prior studies have demonstrated enzyme density on the yWCB surface to be one of the most important parameters for enhancing cellulose hydrolysis, we sought to maximize this parameter at both the population and single-cell levels in yWCBs displaying tetrafunctional minicellulosomes. At the population level, enzyme density is limited by the presence of a nondisplay population constituting 25-50% of all cells. In this study, we identified the cause to be plasmid loss and successfully eliminated the nondisplay population to generate compositionally uniform yWCBs. At the single-cell level, we demonstrate that enzyme density is limited by molecular crowding, which hinders minicellulosome assembly. By adjusting the integrated gene copy number, we obtained yWCBs of tunable enzyme display levels. This tunability allowed us to avoid the crowding-limited regime and achieve a maximum enzyme density per cell. As a result, the best strain showed a cellulose-to-ethanol yield of 4.92 g/g, corresponding to 96% of the theoretical maximum and near-complete conversion (∼96%) of the starting cellulose (1% PASC). Our holistic engineering strategy that combines a population and single-cell level approach is broadly applicable to enhance the WCB performance in other biocatalytic cascade schemes.
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Affiliation(s)
- Xiao Yin Ma
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Catalysis Science and Technology Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Bryan Coleman
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Catalysis Science and Technology Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Ponnandy Prabhu
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Margaret Yang
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Fei Wen
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Catalysis Science and Technology Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
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Dantas-Berto ILO, Viana RLS, de Medeiros MJC, Nobre LTDB, Luchiari AC, Medeiros VP, Paiva WS, Melo-Silveira RF, Rocha HAO. Toward Enhanced Antioxidant and Protective Potential: Conjugation of Corn Cob Xylan with Gallic Acid as a Novel Approach. Int J Mol Sci 2024; 25:2855. [PMID: 38474103 DOI: 10.3390/ijms25052855] [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: 02/06/2024] [Revised: 02/14/2024] [Accepted: 02/17/2024] [Indexed: 03/14/2024] Open
Abstract
Maize ranks as the second most widely produced crop globally, yielding approximately 1.2 billion tons, with corn cob being its primary byproduct, constituting 18 kg per 100 kg of corn. Agricultural corn production generates bioactive polysaccharide-rich byproducts, including xylan (Xyl). In this study, we used the redox method to modify corn cob xylan with gallic acid, aiming to enhance its antioxidant and protective capacity against oxidative stress. The conjugation process resulted in a new molecule termed conjugated xylan-gallic acid (Xyl-GA), exhibiting notable improvements in various antioxidant parameters, including total antioxidant capacity (1.4-fold increase), reducing power (1.2-fold increase), hydroxyl radical scavenging (1.6-fold increase), and cupric chelation (27.5-fold increase) when compared with unmodified Xyl. At a concentration of 1 mg/mL, Xyl-GA demonstrated no cytotoxicity, significantly increased fibroblast cell viability (approximately 80%), and effectively mitigated intracellular ROS levels (reduced by 100%) following oxidative damage induced by H2O2. Furthermore, Xyl-GA exhibited non-toxicity toward zebrafish embryos, offered protection against H2O2-induced stress, and reduced the rate of cells undergoing apoptosis resulting from H2O2 exposure. In conclusion, our findings suggest that Xyl-GA possesses potential therapeutic value in addressing oxidative stress-related disturbances. Further investigations are warranted to elucidate the molecular structure of this novel compound and establish correlations with its pharmacological activities.
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Affiliation(s)
- Isabelle Luna Oliveira Dantas-Berto
- Graduate Program of Health Sciences, Federal University of Rio Grande do Norte (UFRN), Natal 59078-970, RN, Brazil
- Laboratory of Biotechnology of Natural Polymers (BIOPOL), Graduate Program of Biochemistry and Molecular Biology, Bioscience Center, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, RN, Brazil
| | - Rony Lucas Silva Viana
- Laboratory of Biotechnology of Natural Polymers (BIOPOL), Graduate Program of Biochemistry and Molecular Biology, Bioscience Center, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, RN, Brazil
| | - Mayara Jane Campos de Medeiros
- Coordination Chemistry and Polymers Laboratory (LQCPol), Department of Chemistry, Institute of Chemistry, Federal University of Rio Grande do Norte (UFRN), Natal 59078-970, RN, Brazil
| | - Leonardo Thiago Duarte Barreto Nobre
- Laboratory of Biotechnology of Natural Polymers (BIOPOL), Graduate Program of Biochemistry and Molecular Biology, Bioscience Center, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, RN, Brazil
| | - Ana Carolina Luchiari
- Laboratory of Ornamental Fish, Federal University of Rio Grande do Norte, Natal 59078-970, RN, Brazil
| | | | - Weslley Souza Paiva
- Laboratory of Biotechnology of Natural Polymers (BIOPOL), Graduate Program of Biochemistry and Molecular Biology, Bioscience Center, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, RN, Brazil
| | - Raniere Fagundes Melo-Silveira
- Laboratory of Biotechnology of Natural Polymers (BIOPOL), Graduate Program of Biochemistry and Molecular Biology, Bioscience Center, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, RN, Brazil
| | - Hugo Alexandre Oliveira Rocha
- Graduate Program of Health Sciences, Federal University of Rio Grande do Norte (UFRN), Natal 59078-970, RN, Brazil
- Laboratory of Biotechnology of Natural Polymers (BIOPOL), Graduate Program of Biochemistry and Molecular Biology, Bioscience Center, Federal University of Rio Grande do Norte-UFRN, Natal 59078-970, RN, Brazil
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5
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Ma X, Sun C, Xian M, Guo J, Zhang R. Progress in research on the biosynthesis of 1,2,4-butanetriol by engineered microbes. World J Microbiol Biotechnol 2024; 40:68. [PMID: 38200399 DOI: 10.1007/s11274-024-03885-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Accepted: 01/05/2024] [Indexed: 01/12/2024]
Abstract
1,2,4-butanetriol (BT) is a polyol with unique chemical properties, which has a stereocenter and can be divided into D-BT (the S-enantiomer) and L-BT (the R-enantiomer). BT can be used for the synthesis of 1,2,4-butanetriol trinitrate, 3-hydroxytetrahydrofuran, polyurethane, and other chemicals. It is widely used in the military industry, medicine, tobacco, polymer. At present, the BT is mainly synthesized by chemical methods, which are accompanied by harsh reaction conditions, poor selectivity, many by-products, and environmental pollution. Therefore, BT biosynthesis methods with the advantages of mild reaction conditions and green sustainability have become a current research hotspot. In this paper, the research status of microbial synthesis of BT was summarized from the following three aspects: (1) the biosynthetic pathway establishment for BT from xylose; (2) metabolic engineering strategies employed for improving BT production from xylose; (3) other substrates for BT production. Finally, the challenges and prospects of biosynthetic BT were discussed for future methods to improve competitiveness for industrial production.
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Affiliation(s)
- Xiangyu Ma
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chao Sun
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
- Shandong Energy Institute, Qingdao, 266101, China
- Qingdao New Energy Shandong Laboratory, Qingdao, 266101, China
| | - Mo Xian
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
- Shandong Energy Institute, Qingdao, 266101, China
- Qingdao New Energy Shandong Laboratory, Qingdao, 266101, China
| | - Jing Guo
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
- Shandong Energy Institute, Qingdao, 266101, China.
- Qingdao New Energy Shandong Laboratory, Qingdao, 266101, China.
| | - Rubing Zhang
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
- Shandong Energy Institute, Qingdao, 266101, China.
- Qingdao New Energy Shandong Laboratory, Qingdao, 266101, China.
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6
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Ramos MDN, Sandri JP, Claes A, Carvalho BT, Thevelein JM, Zangirolami TC, Milessi TS. Effective application of immobilized second generation industrial Saccharomyces cerevisiae strain on consolidated bioprocessing. N Biotechnol 2023; 78:153-161. [PMID: 37913920 DOI: 10.1016/j.nbt.2023.10.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 09/09/2023] [Accepted: 10/28/2023] [Indexed: 11/03/2023]
Abstract
Integrated bioprocessing strategies can facilitate ethanol production from both cellulose and hemicellulose fractions of lignocellulosic biomass. Consolidated bioprocessing (CBP) is an approach that combines enzyme production, biomass hydrolysis and sugar fermentation in a single step. However, technologies that propose the use of microorganisms together with solid biomass present the difficulty of the recovery and reuse of the biocatalyst, which can be overcome by cell immobilization. In this regard, this work applied immobilized cells of AC14 yeast, a recombinant yeast that secretes 7 hydrolytic enzymes, in the CBP process in a successful proof-of-concept for the enzyme access to the substrate polymers. The most appropriate cell load for CBP under the conditions studied with immobilized cells was selected among three optical densities (OD) 10, 55 and 100. These experiments were performed with free cells to ensure that the results were not biased by mass limitations effects. OD 10 achieved 100% of the sugar consumption and the higher specific production of enzymes, being selected for further studies. Diffusional effects were observed with immobilized cells under static conditions. However, mass transfer limitations were mitigated under agitation, with an 18.5% increase in substrate consumption rate (from 2.7 to 3.5 g/L/h), reaching the same substrate uptake rates as free cells. In addition, immobilized cells achieved 100% hydrolysis and consumption of all substrates offered within only 12 h. Overall, this is the first report of a successful application of immobilized yeast cells in CBP processes for bioethanol production, a promising technology that can be extended to other biorefinery bioproducts.
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Affiliation(s)
- Márcio D N Ramos
- Graduate Program of Chemical Engineering, Federal University of São Carlos (PPGEQ-UFSCar), Rodovia Washington Luís, km 235, 13565-905 São Carlos, SP, Brazil.
| | - Juliana P Sandri
- Graduate Program of Chemical Engineering, Federal University of São Carlos (PPGEQ-UFSCar), Rodovia Washington Luís, km 235, 13565-905 São Carlos, SP, Brazil
| | - Arne Claes
- NovelYeast bv, Bio-Incubator BIO4, Gaston Geenslaan 3, Leuven-Heverlee, Belgium
| | - Bruna T Carvalho
- NovelYeast bv, Bio-Incubator BIO4, Gaston Geenslaan 3, Leuven-Heverlee, Belgium
| | - Johan M Thevelein
- NovelYeast bv, Bio-Incubator BIO4, Gaston Geenslaan 3, Leuven-Heverlee, Belgium
| | - Teresa C Zangirolami
- Graduate Program of Chemical Engineering, Federal University of São Carlos (PPGEQ-UFSCar), Rodovia Washington Luís, km 235, 13565-905 São Carlos, SP, Brazil; Department of Chemical Engineering, Federal University of São Carlos, Rodovia Washington Luís, km 235, 13565-905 São Carlos, SP, Brazil
| | - Thais S Milessi
- Graduate Program of Chemical Engineering, Federal University of São Carlos (PPGEQ-UFSCar), Rodovia Washington Luís, km 235, 13565-905 São Carlos, SP, Brazil; Department of Chemical Engineering, Federal University of São Carlos, Rodovia Washington Luís, km 235, 13565-905 São Carlos, SP, Brazil; Graduate Program of Energy Engineering, Institute of Natural Resources, Federal University of Itajubá, Av. Benedito Pereira dos Santos, 1303, 37500-903 Itajubá, MG, Brazil.
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7
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Qi W, Feng Q, Wang W, Zhang Y, Hu Y, Shakeel U, Xiao L, Wang L, Chen H, Liang C. Combination of surfactants and enzyme cocktails for enhancing woody biomass saccharification and bioethanol production from lab-scale to pilot-scale. BIORESOURCE TECHNOLOGY 2023:129343. [PMID: 37348567 DOI: 10.1016/j.biortech.2023.129343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 06/24/2023]
Abstract
Converting woody biomass to bioethanol might be more affordable, environmentally friendly, and efficient for making biofuel commercially feasible, but it would still need a significant optimization process and expand pilot-scale research. A combination of commercial low enzymes loading at 10 FPU/g glucan and compound additives utilizing Tween 80, PEG8000 and sophorolipid applied from lab-scale to pilot-scale have been studied in this work at economically viable dosages for enhancing bioethanol production. In lab-scale saccharification and fermentation, pretreated poplar at a high solid loading of 20% yielded the highest ethanol titers of 30.96 g/L and theoretical ethanol yield of 92.79%. Additionally, pilot-scale operation was used to investigate the bioethanol amplification, a final volume of 33 m3 which yielded the greatest ethanol amount of 599.6 kg from poplar wood while gaining on-site value-added production of hemicellulosic and cellobiose liquor 1122 kg and lignin residues 2292 kg.
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Affiliation(s)
- Wei Qi
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qifa Feng
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wen Wang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu Zhang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yunzi Hu
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China
| | - Usama Shakeel
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China
| | - Lin Xiao
- Longlive Bio-technology Co., Ltd., Yucheng City, Shandong Province 251200, China
| | - Lan Wang
- State Key Laboratory of Biochemical Engineering, Beijing Key Laboratory of Biomass Refining Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Hongzhang Chen
- State Key Laboratory of Biochemical Engineering, Beijing Key Laboratory of Biomass Refining Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Cuiyi Liang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China.
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8
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Troiano DT, Hofmann T, Brethauer S, Studer MHP. Toward optimal use of biomass as carbon source for chemical bioproduction. Curr Opin Biotechnol 2023; 81:102942. [PMID: 37062153 DOI: 10.1016/j.copbio.2023.102942] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 03/04/2023] [Accepted: 03/17/2023] [Indexed: 04/18/2023]
Abstract
Biomass is widely identified as a promising, renewable replacement for fossil feedstocks in the production of energy, fuels, and chemicals. However, the sustainable supply of biomass is limited. Economic and ecological criteria support prioritization of biomass as a carbon source for organic chemicals; however, utilization for energy currently dominates. Therefore, to optimize the use of available biomass feedstock, biorefining development must focus on high carbon efficiencies and enabling the conversion of all biomass fractions, including lignin and fermentation-derived CO2. Additionally, novel technological platforms should allow the incorporation of nontraditional, currently underutilized carbon feedstocks (e.g. manure) into biorefining processes. To this end, funneling of waste feedstocks to a single product (e.g. methane) and subsequent conversion to chemicals is a promising approach.
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Affiliation(s)
- Derek T Troiano
- School of Agricultural, Forest, and Food Sciences, Bern University of Applied Sciences, CH-3052 Zollikofen, Switzerland
| | - Tobias Hofmann
- School of Agricultural, Forest, and Food Sciences, Bern University of Applied Sciences, CH-3052 Zollikofen, Switzerland
| | - Simone Brethauer
- School of Agricultural, Forest, and Food Sciences, Bern University of Applied Sciences, CH-3052 Zollikofen, Switzerland
| | - Michael H-P Studer
- School of Agricultural, Forest, and Food Sciences, Bern University of Applied Sciences, CH-3052 Zollikofen, Switzerland.
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9
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Lu SY, Liu S, Patel MH, Glenzinski KM, Skory CD. Saccharomyces cerevisiae surface display of endolysin LysKB317 for control of bacterial contamination in corn ethanol fermentations. Front Bioeng Biotechnol 2023; 11:1162720. [PMID: 37091344 PMCID: PMC10117863 DOI: 10.3389/fbioe.2023.1162720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 03/20/2023] [Indexed: 04/09/2023] Open
Abstract
Control of bacterial contamination in bioethanol fermentation facilities has traditionally relied on chemical-based products such as hop acids and use of antibiotics. Recent emphasis on antibiotic stewardship has prompted new research into the development of alternative approaches to microbial remediation strategies. We recently described a recombinant peptidoglycan hydrolase, endolysin LysKB317, which inhibited Limosilactobacillus fermentum strains in corn mash fermentation. Here, Saccharomyces cerevisiae EBY100 was used to anchor recombinant LysKB317 using cell surface display with the a-agglutinin proteins Aga1p–Aga2p. Immunostaining and confocal fluorescence were used for localization of the extracellular interface of the cells. Yeast surface-expressed endolysin demonstrated an 83.8% decrease in bacterial cell counts compared to a 9.5% decrease in control yeast. Recombinant S. cerevisiae expressing LysKB317 used for small-scale corn mash fermentation, when infected with L. fermentum, could proactively control bacterial infection for 72 h with at least 1-log fold reduction. Analysis of fermentation products showed improved ethanol concentrations from 3.4% to at least 5.9% compared to the infection-only control and reduced levels of lactic and acetic acid from 34.7 mM to 13.8 mM and 25.5 mM to 18.1 mM, respectively. In an optimized yeast surface display system, proactive treatment of bacterial contaminants by endolysin LysKB317 can improve fermentation efficiency in the presence of L. fermentum contamination.
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Affiliation(s)
- Shao-Yeh Lu
- Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, Peoria, IL, United States
- *Correspondence: Shao-Yeh Lu,
| | - Siqing Liu
- Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, Peoria, IL, United States
| | - Maulik H. Patel
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN, United States
| | - Kristina M. Glenzinski
- Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, Peoria, IL, United States
| | - Christopher D. Skory
- Renewable Product Technology Research Unit, National Center for Agricultural Utilization Research, USDA, Agricultural Research Service, Peoria, IL, United States
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Baptista SL, Romaní A, Cunha JT, Domingues L. Multi-feedstock biorefinery concept: Valorization of winery wastes by engineered yeast. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 326:116623. [PMID: 36368200 DOI: 10.1016/j.jenvman.2022.116623] [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: 08/05/2022] [Revised: 10/21/2022] [Accepted: 10/23/2022] [Indexed: 06/16/2023]
Abstract
The wine industry produces significant amounts of by-products and residues that are not properly managed, posing an environmental problem. Grape must surplus, vine shoots, and wine lees have the potential to be used as renewable resources for the production of energy and chemicals. Metabolic engineering efforts have established Saccharomyces cerevisiae as an efficient microbial cell factory for biorefineries. Current biorefineries designed for producing multiple products often rely on just one feedstock, but the bioeconomy would clearly benefit if these biorefineries could efficiently convert multiple feedstocks. Moreover, to reduce the environmental impact of fossil fuel consumption and maximize production economics, a biorefinery should be capable to supplement the manufacture of biofuel with the production of high-value products. This study proposes an integrated approach for the valorization of diverse wastes resulting from winemaking processes through the biosynthesis of xylitol and ethanol. Using genetically modified S. cerevisiae strains, the xylose-rich hemicellulosic fraction of hydrothermally pretreated vine shoots was converted into xylitol, and the cellulosic fraction was used to produce bioethanol. In addition, grape must, enriched in sugars, was efficiently used as a low-cost source for yeast propagation. The production of xylitol was optimized, in a Simultaneous Saccharification and Fermentation process configuration, by adjusting the inoculum size and enzyme loading. Furthermore, a yeast strain displaying cellulases in the cell surface was applied for the production of bioethanol from the glucan-rich cellulosic. With the addition of grape must and/or wine lees, high ethanol concentrations were reached, which are crucial for the economic feasibility of distillation. This integrated multi-feedstock valorization provides a synergistic alternative for converting a range of winery wastes and by-products into biofuel and an added-value chemical while decreasing waste released to the environment.
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Affiliation(s)
- Sara L Baptista
- CEB - Centre of Biological Engineering, University of Minho, Braga, Portugal; LABBELS - Associate Laboratory, Braga, Guimarães, Portugal
| | - Aloia Romaní
- Department of Chemical Engineering, Faculty of Science, University of Vigo (Campus Ourense), As Lagoas, 32004, Ourense, Spain
| | - Joana T Cunha
- CEB - Centre of Biological Engineering, University of Minho, Braga, Portugal; LABBELS - Associate Laboratory, Braga, Guimarães, Portugal
| | - Lucília Domingues
- CEB - Centre of Biological Engineering, University of Minho, Braga, Portugal; LABBELS - Associate Laboratory, Braga, Guimarães, Portugal.
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11
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Rodríguez-Martínez B, Coelho E, Gullón B, Yáñez R, Domingues L. Potato peels waste as a sustainable source for biotechnological production of biofuels: Process optimization. WASTE MANAGEMENT (NEW YORK, N.Y.) 2023; 155:320-328. [PMID: 36413884 DOI: 10.1016/j.wasman.2022.11.007] [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: 08/22/2022] [Revised: 10/21/2022] [Accepted: 11/05/2022] [Indexed: 06/16/2023]
Abstract
Potato peel waste (PPW) is a starchy by-product generated in great amounts during the industrial processing of potatoes. It can be used as a low cost alternative, and renewable feedstock for the production of second generation bioethanol. In order to intensify this process, Saccharomyces cerevisiae Ethanol Red®, a robust and thermotolerant yeast strain, was selected and two experimental designs and response surfaces assessment were conducted to enable very high gravity fermentations (VHGF) using PPW as feedstock. The first one focused on the optimization of the liquefaction and enzymatic hydrolysis stages, enabling a maximum ethanol concentration of 116.5 g/L and a yield of 80.4 % at 72 h of fermentation; whereas, the second one, focus on the optimization of the pre-saccharification and fermentation stages, which further increased process productivity, leading to a maximum ethanol concentration of 108.8 g/L and a yield of 75.1 % after 54 h of fermentation. These results allowed the definition of an intensified pre-saccharification and simultaneous saccharification and fermentation (PSSF) process for ethanol production from PPW, resorting to short liquefaction and pre-saccharification times, 2 h and 10 h respectively, at an enzyme loading of 80 U/g PPW of Viscozyme and 5 UE/g PPW of SAN Super and a higher fermentation temperature of 34 °C due to the use of a thermotolerant yeast. Overall, with these conditions and solely from PPW without any supplementation, the outlined PSSF process allowed reaching a high ethanol concentration and yield (104.1 g/L and 71.9 %, respectively) standing at high productivities with only 54 h of fermentation.
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Affiliation(s)
- Beatriz Rodríguez-Martínez
- Universidade de Vigo, Departamento de Enxeñaría Química, Facultade de Ciencias, As Lagoas, 32004 Ourense, Spain
| | - Eduardo Coelho
- CEB-Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal; LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
| | - Beatriz Gullón
- Universidade de Vigo, Departamento de Enxeñaría Química, Facultade de Ciencias, As Lagoas, 32004 Ourense, Spain
| | - Remedios Yáñez
- Universidade de Vigo, Departamento de Enxeñaría Química, Escola de Enxeñaría Industrial, Campus Lagoas-Marcosende 9, Vigo 36310, Spain; CINBIO, Universidade de Vigo, 36310 Vigo, Spain.
| | - Lucília Domingues
- CEB-Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal; LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
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12
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Coimbra L, Malan K, Fagúndez A, Guigou M, Lareo C, Fernández B, Pratto M, Batista S. Fermentation of D-xylose to Ethanol by Saccharomyces cerevisiae CAT-1 Recombinant Strains. BIOENERGY RESEARCH 2023; 16:1001-1012. [PMID: 36248719 PMCID: PMC9540035 DOI: 10.1007/s12155-022-10514-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 08/27/2022] [Indexed: 05/09/2023]
Abstract
Ethanol production by the D-xylose fermentation of lignocellulosic biomass would augment environmental sustainability by increasing the yield of biofuel obtained per cultivated area. A set of recombinant strains derived from the industrial strain Saccharomyces cerevisiae CAT-1 was developed for this purpose. First, two recombinant strains were obtained by the chromosomal insertion of genes involved in the assimilation and transport of D-xylose (Gal2-N376F). Strain CAT-1-XRT was developed with heterologous genes for D-xylose metabolism from the oxo-reductive pathway of Scheffersomyces stipitis (XYL1-K270R, XYL2); and strain CAT-1-XIT, with D-xylose isomerase (xylA gene, XI) from Streptomyces coelicolor. Moreover, both recombinant strains contained extra copies of homologous genes for xylulose kinase (XK) and transaldolase (TAL1). Furthermore, plasmid (pRS42K::XI) was constructed with xylA from Piromyces sp. transferred to CAT-1, CAT-1-XRT, and CAT-1-XIT, followed by an evolution protocol. After 10 subcultures, CAT-1-XIT (pRS42K::XI) consumed 74% of D-xylose, producing 12.6 g/L ethanol (0.31 g ethanol/g D-xylose). The results of this study show that CAT-1-XIT (pRS42K::XI) is a promising recombinant strain for the efficient utilization of D-xylose to produce ethanol from lignocellulosic materials.
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Affiliation(s)
- Lucía Coimbra
- Laboratorio de Microbiología Molecular, Departamento BIOGEM, Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, 11600 Montevideo, CP Uruguay
| | - Karen Malan
- Laboratorio de Microbiología Molecular, Departamento BIOGEM, Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, 11600 Montevideo, CP Uruguay
| | - Alejandra Fagúndez
- Laboratorio de Microbiología Molecular, Departamento BIOGEM, Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, 11600 Montevideo, CP Uruguay
| | - Mairan Guigou
- Departamento de Bioingeniería, Facultad de Ingeniería, Instituto de Ingeniería Química, Universidad de La República. Julio Herrera Y Reissig 565, 11300 Montevideo, CP Uruguay
| | - Claudia Lareo
- Departamento de Bioingeniería, Facultad de Ingeniería, Instituto de Ingeniería Química, Universidad de La República. Julio Herrera Y Reissig 565, 11300 Montevideo, CP Uruguay
| | - Belén Fernández
- Laboratorio de Microbiología Molecular, Departamento BIOGEM, Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, 11600 Montevideo, CP Uruguay
| | - Martín Pratto
- Departamento de Bioingeniería, Facultad de Ingeniería, Instituto de Ingeniería Química, Universidad de La República. Julio Herrera Y Reissig 565, 11300 Montevideo, CP Uruguay
| | - Silvia Batista
- Laboratorio de Microbiología Molecular, Departamento BIOGEM, Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, 11600 Montevideo, CP Uruguay
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13
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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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14
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Efficient Corncob Biorefinery for Ethanol Initiated by a Novel Pretreatment of Densifying Lignocellulosic Biomass with Sulfuric Acid. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8110661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Corncob is a potential feedstock for biorefineries to produce cellulosic ethanol and other chemicals. Densifying lignocellulosic biomass with chemicals followed by autoclave (DLCA) has been confirmed an efficient and economical pretreatment method, and it was applied in the present work for conversion of corncob to bioethanol. The dosage of sulfuric acid, solid loading of biomass, and autoclave time for pretreatment were investigated. Enzymatic hydrolysis at 25–35% solids loadings resulted in 91–97% sugar conversions. Fermentation of the resulted hydrolysates went well with the highest ethanol titer reaching 75.71 g/L at 35% solid loading. Simultaneous saccharification and co-fermentation was applied to further improve xylose consumption at high solids loadings and the ethanol titer was enhanced to 82.0 g/L at 35% solid loading with an ethanol yield of 21.67 kg/100 kg corncob. This study demonstrated DLCA provided a highly digestible and highly fermentable corncob for biorefinery.
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15
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Overexpression of LAS21 in Cellulase-Displaying Saccharomyces cerevisiae for High-Yield Ethanol Production from Pretreated Sugarcane Bagasse. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8110652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The valorization of lignocellulosic feedstocks into biofuels and biochemicals has received much attention due to its environmental friendliness and sustainability. However, engineering an ideal microorganism that can both produce sufficient cellulases and ferment ethanol is highly challenging. In this study, we have tested seven different genes that are involved in glycosylphosphatidylinositol (GPI) biosynthesis and remodeling for the improvement of cellulase activity tethered on the S. cerevisiae cell surface. It was found that the overexpression of LAS21 can improve β-glucosidase activity by 48.8% compared to the original strain. Then, the three cellulase genes (cellobiohydrolase, endoglucanase, and β-glucosidase) and the LAS21 gene were co-introduced into a diploid thermotolerant S. cerevisiae strain by a multiple-round transformation approach, resulting in the cellulolytic ECBLCCE5 strain. Further optimization of the bioprocess parameters was found to enhance the ethanol yield of the ECBLCCE5 strain. Scaling up the valorization of pretreated sugarcane bagasses in a 1 L bioreactor resulted in a maximum ethanol concentration of 28.0 g/L (86.5% of theoretical yield). Our study provides a promising way to improve the economic viability of second-generation ethanol production. Moreover, the engineering of genes involved in GPI biosynthesis and remodeling can be applied to other yeast cell surface display applications.
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16
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Zanuso E, Ruiz HA, Domingues L, Teixeira JA. Oscillatory flow bioreactor operating at high solids loading for enzymatic hydrolysis of lignocellulosic biomass. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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17
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Costa CE, Romaní A, Teixeira JA, Domingues L. Resveratrol production for the valorisation of lactose-rich wastes by engineered industrial Saccharomyces cerevisiae. BIORESOURCE TECHNOLOGY 2022; 359:127463. [PMID: 35710047 DOI: 10.1016/j.biortech.2022.127463] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 06/08/2022] [Accepted: 06/10/2022] [Indexed: 06/15/2023]
Abstract
Resveratrol is an antioxidant with applications in the food and cosmetic industries. Its biosynthesis can side the hindrances of its extraction from plants. The dairy industry generates tonnes of lactose-rich wastes, which can be a carbon source. Saccharomyces cerevisiae is an industrial workhorse for biotechnological processes, being unable to naturally metabolise lactose. Here, an S. cerevisiae strain was engineered for de novo production of resveratrol from lactose. A resveratrol titre of 210 mg/L from 100 g/L of lactose in synthetic media was achieved. Process optimization increased by 35% the production by a two-stage process, one favouring ethanol production and a subsequent one with stronger agitation favouring ethanol and lactose consumption with conversion into resveratrol. Resveratrol production from cheese whey was further attained. To the best knowledge of the authors, this is the first report on resveratrol production from lactose, relevant in dairy wastes, establishing grounds for future resveratrol-producing lactose-based processes.
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Affiliation(s)
- Carlos E Costa
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal; LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
| | - Aloia Romaní
- Department of Chemical Engineering, Faculty of Science, University of Vigo (Campus Ourense), As Lagoas, 32004 Ourense, Spain
| | - José A Teixeira
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal; LABBELS - Associate Laboratory, Braga/Guimarães, Portugal
| | - Lucília Domingues
- CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal; LABBELS - Associate Laboratory, Braga/Guimarães, Portugal.
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18
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Singhania RR, Patel AK, Singh A, Haldar D, Soam S, Chen CW, Tsai ML, Dong CD. Consolidated bioprocessing of lignocellulosic biomass: Technological advances and challenges. BIORESOURCE TECHNOLOGY 2022; 354:127153. [PMID: 35421566 DOI: 10.1016/j.biortech.2022.127153] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/08/2022] [Accepted: 04/09/2022] [Indexed: 06/14/2023]
Abstract
Consolidated bioprocessing (CBP) is characterized by a single-step production of value-added compounds directly from biomass in a single vessel. This strategy has the capacity to revolutionize the whole biorefinery concept as it can significantly reduce the infrastructure input and use of chemicals for various processing steps which can make it economically and environmentally benign. Although the proof of concept has been firmly established in the past, commercialization has been limited due to the low conversion efficiency of the technology. Either a native single microbe, genetically modified microbe or a consortium can be employed. The major challenge in developing a cost-effective and feasible CBP process is the recognition of bifunctional catalysts combining the capability to use the substrates and transform them into value-added products with high efficiency. This article presents an in-depth analysis of the current developments in CBP around the globe and the possibilities of advancements in the future.
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Affiliation(s)
- Reeta Rani Singhania
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan; Centre for Energy and Environmental Sustainability, Lucknow 226 029, India
| | - Anil Kumar Patel
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan; Centre for Energy and Environmental Sustainability, Lucknow 226 029, India
| | - Anusuiya Singh
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Dibyajyoti Haldar
- Department of Biotechnology, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu 641114, India
| | - Shveta Soam
- Department of Building Engineering, Energy Systems and Sustainability Science, University of Gävle, Kungsbäcksvägen 47, 80176 Gävle, Sweden
| | - Chiu-Wen Chen
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan; Institute of Aquatic Science and Technology, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Mei-Ling Tsai
- Department of Seafood Science, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Cheng-Di Dong
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan; Institute of Aquatic Science and Technology, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan.
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19
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Li Y, Li C, Huang H, Rao S, Zhang Q, Zhou J, Li J, Du G, Liu S. Significantly Enhanced Thermostability of Aspergillus niger Xylanase by Modifying Its Highly Flexible Regions. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:4620-4630. [PMID: 35404048 DOI: 10.1021/acs.jafc.2c01343] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this study, the thermostability of an acid-resistant GH11 xylanase (xynA) from Aspergillus niger AG11 was enhanced through systematic modification of its four highly flexible regions (HFRs) predicted using MD simulations. Among them, HFR I (residues 92-100) and HFR II (residues 121-130) were modified by iterative saturation mutagenesis (ISM), yielding mutants G92F/G97S/G100K and T121V/A124P/I126V/T129L/A130N, respectively. For HFR III, the N-(residues 1-37) and C-termini (residues 179-188) were, respectively, substituted with the corresponding sequences from thermophilic EvXyn11TS and Nesterenkonia xinjiangensis xylanase. N-Glycosylation was introduced into HFR IV (residues 50-70) through site-directed mutation (A55N/D57S/S61N) and the recombinant expression in A. niger AG11. Combining these positive mutations from each HFR yielded the variant xynAm1 with 137.6- and 1.3-fold increases in half-life at 50 °C and specific activity compared to the wild-type xynA, respectively. With the highest thermostability at 80 and 90 °C in reports, xynAm1 could be a robust candidate for industrial applications in functional foods, feed products, and bioethanol production.
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Affiliation(s)
- Yangyang Li
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Cen Li
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Hao Huang
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Shengqi Rao
- College of Food Science and Engineering, Yangzhou University, Yangzhou 214122, China
| | - Quan Zhang
- Dalian Research Institute of Petroleum and Petrochemicals, SINOPEC, Dalian 116000, China
| | - Jingwen Zhou
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
- Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jianghua Li
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Guocheng Du
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Song Liu
- National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
- School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
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20
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Sharma J, Kumar V, Prasad R, Gaur NA. Engineering of Saccharomyces cerevisiae as a consolidated bioprocessing host to produce cellulosic ethanol: Recent advancements and current challenges. Biotechnol Adv 2022; 56:107925. [DOI: 10.1016/j.biotechadv.2022.107925] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/24/2022] [Accepted: 02/06/2022] [Indexed: 01/01/2023]
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21
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Gronchi N, De Bernardini N, Cripwell RA, Treu L, Campanaro S, Basaglia M, Foulquié-Moreno MR, Thevelein JM, Van Zyl WH, Favaro L, Casella S. Natural Saccharomyces cerevisiae Strain Reveals Peculiar Genomic Traits for Starch-to-Bioethanol Production: the Design of an Amylolytic Consolidated Bioprocessing Yeast. Front Microbiol 2022; 12:768562. [PMID: 35126325 PMCID: PMC8815085 DOI: 10.3389/fmicb.2021.768562] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 12/17/2021] [Indexed: 11/13/2022] Open
Abstract
Natural yeast with superior fermentative traits can serve as a platform for the development of recombinant strains that can be used to improve the sustainability of bioethanol production from starch. This process will benefit from a consolidated bioprocessing (CBP) approach where an engineered strain producing amylases directly converts starch into ethanol. The yeast Saccharomyces cerevisiae L20, previously selected as outperforming the benchmark yeast Ethanol Red, was here subjected to a comparative genomic investigation using a dataset of industrial S. cerevisiae strains. Along with Ethanol Red, strain L20 was then engineered for the expression of α-amylase amyA and glucoamylase glaA genes from Aspergillus tubingensis by employing two different approaches (delta integration and CRISPR/Cas9). A correlation between the number of integrated copies and the hydrolytic abilities of the recombinants was investigated. L20 demonstrated important traits for the construction of a proficient CBP yeast. Despite showing a close relatedness to commercial wine yeast and the benchmark Ethanol Red, a unique profile of gene copy number variations (CNVs) was found in L20, mainly encoding membrane transporters and secretion pathway proteins but also the fermentative metabolism. Moreover, the genome annotation disclosed seven open reading frames (ORFs) in L20 that are absent in the reference S288C genome. Genome engineering was successfully implemented for amylase production. However, with equal amylase gene copies, L20 proved its proficiency as a good enzyme secretor by exhibiting a markedly higher amylolytic activity than Ethanol Red, in compliance to the findings of the genomic exploration. The recombinant L20 dT8 exhibited the highest amylolytic activity and produced more than 4 g/L of ethanol from 2% starch in a CBP setting without the addition of supplementary enzymes. Based on the performance of this strain, an amylase/glucoamylase ratio of 1:2.5 was suggested as baseline for further improvement of the CBP ability. Overall, L20 showed important traits for the future construction of a proficient CBP yeast. As such, this work shows that natural S. cerevisiae strains can be used for the expression of foreign secreted enzymes, paving the way to strain improvement for the starch-to-bioethanol route.
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Affiliation(s)
- Nicoletta Gronchi
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, Legnaro, Italy
| | | | - Rosemary A Cripwell
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Laura Treu
- Department of Biology, University of Padua, Padua, Italy
| | | | - Marina Basaglia
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, Legnaro, Italy
| | | | - Johan M Thevelein
- Department of Molecular Microbiology, VIB, KU Leuven, Leuven, Belgium
- NovelYeast Bv, Open Bio-Incubator, Erasmus High School, Jette, Belgium
| | - Willem H Van Zyl
- Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
| | - Lorenzo Favaro
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, Legnaro, Italy
| | - Sergio Casella
- Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, Legnaro, Italy
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Narisetty V, Cox R, Bommareddy R, Agrawal D, Ahmad E, Pant KK, Chandel AK, Bhatia SK, Kumar D, Binod P, Gupta VK, Kumar V. Valorisation of xylose to renewable fuels and chemicals, an essential step in augmenting the commercial viability of lignocellulosic biorefineries. SUSTAINABLE ENERGY & FUELS 2021; 6:29-65. [PMID: 35028420 PMCID: PMC8691124 DOI: 10.1039/d1se00927c] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 10/25/2021] [Indexed: 05/30/2023]
Abstract
Biologists and engineers are making tremendous efforts in contributing to a sustainable and green society. To that end, there is growing interest in waste management and valorisation. Lignocellulosic biomass (LCB) is the most abundant material on the earth and an inevitable waste predominantly originating from agricultural residues, forest biomass and municipal solid waste streams. LCB serves as the renewable feedstock for clean and sustainable processes and products with low carbon emission. Cellulose and hemicellulose constitute the polymeric structure of LCB, which on depolymerisation liberates oligomeric or monomeric glucose and xylose, respectively. The preferential utilization of glucose and/or absence of the xylose metabolic pathway in microbial systems cause xylose valorization to be alienated and abandoned, a major bottleneck in the commercial viability of LCB-based biorefineries. Xylose is the second most abundant sugar in LCB, but a non-conventional industrial substrate unlike glucose. The current review seeks to summarize the recent developments in the biological conversion of xylose into a myriad of sustainable products and associated challenges. The review discusses the microbiology, genetics, and biochemistry of xylose metabolism with hurdles requiring debottlenecking for efficient xylose assimilation. It further describes the product formation by microbial cell factories which can assimilate xylose naturally and rewiring of metabolic networks to ameliorate xylose-based bioproduction in native as well as non-native strains. The review also includes a case study that provides an argument on a suitable pathway for optimal cell growth and succinic acid (SA) production from xylose through elementary flux mode analysis. Finally, a product portfolio from xylose bioconversion has been evaluated along with significant developments made through enzyme, metabolic and process engineering approaches, to maximize the product titers and yield, eventually empowering LCB-based biorefineries. Towards the end, the review is wrapped up with current challenges, concluding remarks, and prospects with an argument for intense future research into xylose-based biorefineries.
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Affiliation(s)
- Vivek Narisetty
- School of Water, Energy and Environment, Cranfield University Cranfield MK43 0AL UK +44 (0)1234754786
| | - Rylan Cox
- School of Water, Energy and Environment, Cranfield University Cranfield MK43 0AL UK +44 (0)1234754786
- School of Aerospace, Transport and Manufacturing, Cranfield University Cranfield MK43 0AL UK
| | - Rajesh Bommareddy
- Department of Applied Sciences, Northumbria University Newcastle upon Tyne NE1 8ST UK
| | - Deepti Agrawal
- Biochemistry and Biotechnology Area, Material Resource Efficiency Division, CSIR- Indian Institute of Petroleum Mohkampur Dehradun 248005 India
| | - Ejaz Ahmad
- Department of Chemical Engineering, Indian Institute of Technology (ISM) Dhanbad 826004 India
| | - Kamal Kumar Pant
- Department of Chemical Engineering, Indian Institute of Technology Delhi New Delhi 110016 India
| | - Anuj Kumar Chandel
- Department of Biotechnology, Engineering School of Lorena (EEL), University of São Paulo Lorena 12.602.810 Brazil
| | - Shashi Kant Bhatia
- Department of Biological Engineering, College of Engineering, Konkuk University Seoul 05029 Republic of Korea
| | - Dinesh Kumar
- School of Bioengineering & Food Technology, Shoolini University of Biotechnology and Management Sciences Solan 173229 Himachal Pradesh India
| | - Parmeswaran Binod
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (CSIR-NIIST) Thiruvananthapuram 695 019 Kerala India
| | | | - Vinod Kumar
- School of Water, Energy and Environment, Cranfield University Cranfield MK43 0AL UK +44 (0)1234754786
- Department of Chemical Engineering, Indian Institute of Technology Delhi New Delhi 110016 India
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23
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Scapini T, Dos Santos MSN, Bonatto C, Wancura JHC, Mulinari J, Camargo AF, Klanovicz N, Zabot GL, Tres MV, Fongaro G, Treichel H. Hydrothermal pretreatment of lignocellulosic biomass for hemicellulose recovery. BIORESOURCE TECHNOLOGY 2021; 342:126033. [PMID: 34592451 DOI: 10.1016/j.biortech.2021.126033] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 09/21/2021] [Accepted: 09/23/2021] [Indexed: 06/13/2023]
Abstract
The hemicellulosic fraction recovery is of interest for integrated processes in biorefineries, considering the possibility of high economic value products produced from their structural compounds of this polysaccharide. However, to perform an efficient recovery, it is necessary to use biomass fractionation techniques, and hydrothermal pretreatment is highlighted as a valuable technique in the hemicellulose recovery by applying high temperatures and pressure, causing dissolution of the structure. Considering the possibility of this pretreatment technique for current approaches to hemicellulose recovery, this article aimed to explore the relevance of hydrothermal pretreatment techniques (sub and supercritical water) as a strategy for recovering the hemicellulosic fraction from lignocellulosic biomass. Discussions about potential products to be generated, current market profile, and perspectives and challenges of applying the technique are also addressed.
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Affiliation(s)
- Thamarys Scapini
- Laboratory of Microbiology and Bioprocess (LAMIBI), Federal University of Fronteira Sul, Erechim, RS, Brazil; Department of Biological Science, Graduate Program in Biotechnology and Bioscience, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Maicon S N Dos Santos
- Laboratory of Agroindustrial Processes Engineering (LAPE), Federal University of Santa Maria, Cachoeira do Sul, RS, Brazil
| | - Charline Bonatto
- Laboratory of Microbiology and Bioprocess (LAMIBI), Federal University of Fronteira Sul, Erechim, RS, Brazil
| | | | - Jéssica Mulinari
- Laboratory of Membrane Processes, Department of Chemical Engineering and Food Engineering, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Aline F Camargo
- Laboratory of Microbiology and Bioprocess (LAMIBI), Federal University of Fronteira Sul, Erechim, RS, Brazil; Department of Biological Science, Graduate Program in Biotechnology and Bioscience, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Natalia Klanovicz
- Laboratory of Microbiology and Bioprocess (LAMIBI), Federal University of Fronteira Sul, Erechim, RS, Brazil; Research Group in Advanced Oxidation Processes (AdOx), Department of Chemical Engineering, Escola Politécnica, University of São Paulo, São Paulo, SP, Brazil
| | - Giovani L Zabot
- Laboratory of Agroindustrial Processes Engineering (LAPE), Federal University of Santa Maria, Cachoeira do Sul, RS, Brazil
| | - Marcus V Tres
- Laboratory of Agroindustrial Processes Engineering (LAPE), Federal University of Santa Maria, Cachoeira do Sul, RS, Brazil
| | - Gislaine Fongaro
- Department of Biological Science, Graduate Program in Biotechnology and Bioscience, Federal University of Santa Catarina, Florianópolis, SC, Brazil; Laboratory of Applied Virology, Department of Microbiology, Immunology, and Parasitology, Federal University of Santa Catarina, Florianópolis, SC, Brazil
| | - Helen Treichel
- Laboratory of Microbiology and Bioprocess (LAMIBI), Federal University of Fronteira Sul, Erechim, RS, Brazil; Department of Biological Science, Graduate Program in Biotechnology and Bioscience, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
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24
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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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25
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Stress modulation as a means to improve yeasts for lignocellulose bioconversion. Appl Microbiol Biotechnol 2021; 105:4899-4918. [PMID: 34097119 DOI: 10.1007/s00253-021-11383-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 05/20/2021] [Accepted: 05/28/2021] [Indexed: 12/15/2022]
Abstract
The second-generation (2G) fermentation environment for lignocellulose conversion presents unique challenges to the fermentative organism that do not necessarily exist in other industrial fermentations. While extreme osmotic, heat, and nutrient starvation stresses are observed in sugar- and starch-based fermentation environments, additional pre-treatment-derived inhibitor stress, potentially exacerbated by stresses such as pH and product tolerance, exist in the 2G environment. Furthermore, in a consolidated bioprocessing (CBP) context, the organism is also challenged to secrete enzymes that may themselves lead to unfolded protein response and other stresses. This review will discuss responses of the yeast Saccharomyces cerevisiae to 2G-specific stresses and stress modulation strategies that can be followed to improve yeasts for this application. We also explore published -omics data and discuss relevant rational engineering, reverse engineering, and adaptation strategies, with the view of identifying genes or alleles that will make positive contributions to the overall robustness of 2G industrial strains. KEYPOINTS: • Stress tolerance is a key driver to successful application of yeast strains in biorefineries. • A wealth of data regarding stress responses has been gained through omics studies. • Integration of this knowledge could inform engineering of fit for purpose strains.
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26
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Strategies towards Reduction of Cellulases Consumption: Debottlenecking the Economics of Lignocellulosics Valorization Processes. POLYSACCHARIDES 2021. [DOI: 10.3390/polysaccharides2020020] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Lignocellulosic residues have been receiving growing interest as a promising source of polysaccharides, which can be converted into a variety of compounds, ranging from biofuels to bioplastics. Most of these can replace equivalent products traditionally originated from petroleum, hence representing an important environmental advantage. Lignocellulosic materials are theoretically unlimited, cheaper and may not compete with food crops. However, the conversion of these materials to simpler sugars usually requires cellulolytic enzymes. Being still associated with a high cost of production, cellulases are commonly considered as one of the main obstacles in the economic valorization of lignocellulosics. This work provides a brief overview of some of the most studied strategies that can allow an important reduction of cellulases consumption, hence improving the economy of lignocellulosics conversion. Cellulases recycling is initially discussed regarding the main processes to recover active enzymes and the most important factors that may affect enzyme recyclability. Similarly, the potential of enzyme immobilization is analyzed with a special focus on the contributions that some elements of the process can offer for prolonged times of operation and improved enzyme stability and robustness. Finally, the emergent concept of consolidated bioprocessing (CBP) is also described in the particular context of a potential reduction of cellulases consumption.
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27
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Abstract
Over the last decades, the constant growth of the world-wide industry has been leading to more and more concerns with its direct impact on greenhouse gas (GHG) emissions. Resulting from that, rising efforts have been dedicated to a global transition from an oil-based industry to cleaner biotechnological processes. A specific example refers to the production of bioethanol to substitute the traditional transportation fuels. Bioethanol has been produced for decades now, mainly from energy crops, but more recently, also from lignocellulosic materials. Aiming to improve process economics, the fermentation of very high gravity (VHG) mediums has for long received considerable attention. Nowadays, with the growth of multi-waste valorization frameworks, VHG fermentation could be crucial for bioeconomy development. However, numerous obstacles remain. This work initially presents the main aspects of a VHG process, giving then special emphasis to some of the most important factors that traditionally affect the fermentation organism, such as nutrients depletion, osmotic stress, and ethanol toxicity. Afterwards, some factors that could possibly enable critical improvements in the future on VHG technologies are discussed. Special attention was given to the potential of the development of new fermentation organisms, nutritionally complete culture media, but also on alternative process conditions and configurations.
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28
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Jin M, Shi Y, Du X, Wu S, Wang L, Qiao N, Yu D. High temperature treatment of hemicellulose in pulp-impregnated effluent improves the pre-hydrolysis efficiency. NEW J CHEM 2021. [DOI: 10.1039/d1nj00536g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
At 121 °C, the heat transfer effect and the movement of H3O+ are improved, thus the pre-hydrolysis is accelerated.
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Affiliation(s)
- Meitong Jin
- Sci-Tech Center for Clean Conversion and High-valued Utilization of Biomass
- Jilin Province
- Northeast Electric Power University
- Jilin 132012
- China
| | - Yunfen Shi
- Sci-Tech Center for Clean Conversion and High-valued Utilization of Biomass
- Jilin Province
- Northeast Electric Power University
- Jilin 132012
- China
| | - Xinhong Du
- Sci-Tech Center for Clean Conversion and High-valued Utilization of Biomass
- Jilin Province
- Northeast Electric Power University
- Jilin 132012
- China
| | - Song Wu
- Sci-Tech Center for Clean Conversion and High-valued Utilization of Biomass
- Jilin Province
- Northeast Electric Power University
- Jilin 132012
- China
| | - Lei Wang
- Sci-Tech Center for Clean Conversion and High-valued Utilization of Biomass
- Jilin Province
- Northeast Electric Power University
- Jilin 132012
- China
| | - Nan Qiao
- Sci-Tech Center for Clean Conversion and High-valued Utilization of Biomass
- Jilin Province
- Northeast Electric Power University
- Jilin 132012
- China
| | - Dayu Yu
- Sci-Tech Center for Clean Conversion and High-valued Utilization of Biomass
- Jilin Province
- Northeast Electric Power University
- Jilin 132012
- China
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29
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Cunha JT, Soares PO, Baptista SL, Costa CE, Domingues L. Engineered Saccharomyces cerevisiae for lignocellulosic valorization: a review and perspectives on bioethanol production. Bioengineered 2020; 11:883-903. [PMID: 32799606 PMCID: PMC8291843 DOI: 10.1080/21655979.2020.1801178] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The biorefinery concept, consisting in using renewable biomass with economical and energy goals, appeared in response to the ongoing exhaustion of fossil reserves. Bioethanol is the most prominent biofuel and has been considered one of the top chemicals to be obtained from biomass. Saccharomyces cerevisiae, the preferred microorganism for ethanol production, has been the target of extensive genetic modifications to improve the production of this alcohol from renewable biomasses. Additionally, S. cerevisiae strains from harsh industrial environments have been exploited due to their robust traits and improved fermentative capacity. Nevertheless, there is still not an optimized strain capable of turning second generation bioprocesses economically viable. Considering this, and aiming to facilitate and guide the future development of effective S. cerevisiae strains, this work reviews genetic engineering strategies envisioning improvements in 2nd generation bioethanol production, with special focus in process-related traits, xylose consumption, and consolidated bioprocessing. Altogether, the genetic toolbox described proves S. cerevisiae to be a key microorganism for the establishment of a bioeconomy, not only for the production of lignocellulosic bioethanol, but also having potential as a cell factory platform for overall valorization of renewable biomasses.
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Affiliation(s)
- Joana T Cunha
- CEB - Centre of Biological Engineering, University of Minho, Campus Gualtar , Braga, Portugal
| | - Pedro O Soares
- CEB - Centre of Biological Engineering, University of Minho, Campus Gualtar , Braga, Portugal
| | - Sara L Baptista
- CEB - Centre of Biological Engineering, University of Minho, Campus Gualtar , Braga, Portugal
| | - Carlos E Costa
- CEB - Centre of Biological Engineering, University of Minho, Campus Gualtar , Braga, Portugal
| | - Lucília Domingues
- CEB - Centre of Biological Engineering, University of Minho, Campus Gualtar , Braga, Portugal
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