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Ali SA, Songdech P, Samakkarn W, Duangphakdee O, Soontorngun N. New regulatory role of Znf1 in transcriptional control of pentose phosphate pathway and ATP synthesis for enhanced isobutanol and acid tolerance. Yeast 2024. [PMID: 38708451 DOI: 10.1002/yea.3940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 02/20/2024] [Accepted: 04/15/2024] [Indexed: 05/07/2024] Open
Abstract
To develop a cost-effective microbial cell factory for the production of biofuels and biochemicals, an understanding of tolerant mechanisms is vital for the construction of robust host strains. Here, we characterized a new function of a key metabolic transcription factor named Znf1 and its involvement in stress response in Saccharomyces cerevisiae to enhance tolerance to advanced biofuel, isobutanol. RNA-sequencing analysis of the wild-type versus the znf1Δ deletion strains in glucose revealed a new role for transcription factor Znf1 in the pentose phosphate pathway (PPP) and energy generation. The gene expression analysis confirmed that isobutanol induces an adaptive cell response, resulting in activation of ATP1-3 and COX6 expression. These genes were Znf1 targets that belong to the electron transport chain, important to produce ATPs. Znf1 also activated PPP genes, required for the generation of key amino acids, cellular metabolites, and maintenance of NADP/NADPH redox balance. In glucose, Znf1 also mediated the upregulation of valine biosynthetic genes of the Ehrlich pathway, namely ILV3, ILV5, and ARO10, associated with the generation of key intermediates for isobutanol production. Using S. cerevisiae knockout collection strains, cells with deleted transcriptional regulatory gene ZNF1 or its targets displayed hypersensitivity to isobutanol and acid inhibitors; in contrast, overexpression of ZNF1 enhanced cell survival. Thus, the transcription factor Znf1 functions in the maintenance of energy homeostasis and redox balance at various checkpoints of yeast metabolic pathways. It ensures the rapid unwiring of gene transcription in response to toxic products/by-products generated during biofuel production. Importantly, we provide a new approach to enhance strain tolerance during the conversion of glucose to biofuels.
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Affiliation(s)
- Syed Azhar Ali
- Excellent Research Laboratory for Yeast Innovation, School of Bioresources and Technology, Division of Biochemical Technology, King Mongkut's University of Technology Thonburi, Bangkok, Thailand
| | - Pattanan Songdech
- Excellent Research Laboratory for Yeast Innovation, School of Bioresources and Technology, Division of Biochemical Technology, King Mongkut's University of Technology Thonburi, Bangkok, Thailand
| | - Wiwan Samakkarn
- Excellent Research Laboratory for Yeast Innovation, School of Bioresources and Technology, Division of Biochemical Technology, King Mongkut's University of Technology Thonburi, Bangkok, Thailand
| | - Orawan Duangphakdee
- Native Honeybee and Pollinator Research Center, King Mongkut's University of Technology Thonburi, Ratchaburi, Thailand
| | - Nitnipa Soontorngun
- Excellent Research Laboratory for Yeast Innovation, School of Bioresources and Technology, Division of Biochemical Technology, King Mongkut's University of Technology Thonburi, Bangkok, Thailand
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Torello Pianale L, Caputo F, Olsson L. Four ways of implementing robustness quantification in strain characterisation. Biotechnol Biofuels Bioprod 2023; 16:195. [PMID: 38115067 PMCID: PMC10729505 DOI: 10.1186/s13068-023-02445-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 12/05/2023] [Indexed: 12/21/2023]
Abstract
BACKGROUND In industrial bioprocesses, microorganisms are generally selected based on performance, whereas robustness, i.e., the ability of a system to maintain a stable performance, has been overlooked due to the challenges in its quantification and implementation into routine experimental procedures. This work presents four ways of implementing robustness quantification during strain characterisation. One Saccharomyces cerevisiae laboratory strain (CEN.PK113-7D) and two industrial strains (Ethanol Red and PE2) grown in seven different lignocellulosic hydrolysates were assessed for growth-related functions (specific growth rate, product yields, etc.) and eight intracellular parameters (using fluorescent biosensors). RESULTS Using flasks and high-throughput experimental setups, robustness was quantified in relation to: (i) stability of growth functions in response to the seven hydrolysates; (ii) stability of growth functions across different strains to establish the impact of perturbations on yeast metabolism; (iii) stability of intracellular parameters over time; (iv) stability of intracellular parameters within a cell population to indirectly quantify population heterogeneity. Ethanol Red was the best-performing strain under all tested conditions, achieving the highest growth function robustness. PE2 displayed the highest population heterogeneity. Moreover, the intracellular environment varied in response to non-woody or woody lignocellulosic hydrolysates, manifesting increased oxidative stress and unfolded protein response, respectively. CONCLUSIONS Robustness quantification is a powerful tool for strain characterisation as it offers novel information on physiological and biochemical parameters. Owing to the flexibility of the robustness quantification method, its implementation was successfully validated at single-cell as well as high-throughput levels, showcasing its versatility and potential for several applications.
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Affiliation(s)
- Luca Torello Pianale
- Industrial Biotechnology Division, Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | - Fabio Caputo
- Industrial Biotechnology Division, Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | - Lisbeth Olsson
- Industrial Biotechnology Division, Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden.
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Dolpatcha S, Phong HX, Thanonkeo S, Klanrit P, Yamada M, Thanonkeo P. Adaptive laboratory evolution under acetic acid stress enhances the multistress tolerance and ethanol production efficiency of Pichia kudriavzevii from lignocellulosic biomass. Sci Rep 2023; 13:21000. [PMID: 38017261 PMCID: PMC10684600 DOI: 10.1038/s41598-023-48408-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Accepted: 11/26/2023] [Indexed: 11/30/2023] Open
Abstract
Second-generation bioethanol production using lignocellulosic biomass as feedstock requires a highly efficient multistress-tolerant yeast. This study aimed to develop a robust yeast strain of P. kudriavzevii via the adaptive laboratory evolution (ALE) technique. The parental strain of P. kudriavzevii was subjected to repetitive long-term cultivation in medium supplemented with a gradually increasing concentration of acetic acid, the major weak acid liberated during the lignocellulosic pretreatment process. Three evolved P. kudriavzevii strains, namely, PkAC-7, PkAC-8, and PkAC-9, obtained in this study exhibited significantly higher resistance toward multiple stressors, including heat, ethanol, osmotic stress, acetic acid, formic acid, furfural, 5-(hydroxymethyl) furfural (5-HMF), and vanillin. The fermentation efficiency of the evolved strains was also improved, yielding a higher ethanol concentration, productivity, and yield than the parental strain, using undetoxified sugarcane bagasse hydrolysate as feedstock. These findings provide evidence that ALE is a practical approach for increasing the multistress tolerance of P. kudriavzevii for stable and efficient second-generation bioethanol production from lignocellulosic biomass.
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Affiliation(s)
- Sureeporn Dolpatcha
- Department of Biotechnology, Faculty of Technology, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Huynh Xuan Phong
- Department of Microbial Biotechnology, Institute of Food and Biotechnology, Can Tho University, Can Tho, 900000, Vietnam
| | - Sudarat Thanonkeo
- Walai Rukhavej Botanical Research Institute, Mahasarakham University, Maha Sarakham, 44150, Thailand
| | - Preekamol Klanrit
- Department of Biotechnology, Faculty of Technology, Khon Kaen University, Khon Kaen, 40002, Thailand
- Fermentation Research Center for Value Added Agricultural Products (FerVAAPs), Faculty of Technology, Khon Kaen University, Khon Kaen, 40002, Thailand
| | - Mamoru Yamada
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi, 753-8515, Japan
- Research Center for Thermotolerant Microbial Resources, Yamaguchi University, Yamaguchi, 753-8515, Japan
| | - Pornthap Thanonkeo
- Department of Biotechnology, Faculty of Technology, Khon Kaen University, Khon Kaen, 40002, Thailand.
- Fermentation Research Center for Value Added Agricultural Products (FerVAAPs), Faculty of Technology, Khon Kaen University, Khon Kaen, 40002, Thailand.
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Kłosowski G, Koim-Puchowska B, Dróżdż-Afelt J, Mikulski D. The Reaction of the Yeast Saccharomyces cerevisiae to Contamination of the Medium with Aflatoxins B 2 and G 1, Ochratoxin A and Zearalenone in Aerobic Cultures. Int J Mol Sci 2023; 24:16401. [PMID: 38003590 PMCID: PMC10671187 DOI: 10.3390/ijms242216401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 10/25/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
The mechanisms by which yeast cells respond to environmental stress include the production of heat shock proteins (HSPs) and the reduction of oxidative stress. The response of yeast exposed to aflatoxins B2+G1 (AFB2+G1), ochratoxin A (OTA), and zearalenone (ZEA) in aerobic conditions was studied. After 72 h of yeast cultivation in media contaminated with mycotoxins, the growth of yeast biomass, the level of malondialdehyde, and the activity of superoxide dismutase, glutathione S-transferase and glutathione peroxidase were examined; the expression profile of the following heat shock proteins was also determined: HSP31, HSP40, HSP60, HSP70, and HSP104. It was demonstrated that at the tested concentrations, both AFB2+G1 and ZEA inhibited yeast biomass growth. OTA at a concentration of 8.4 [µg/L] raised the MDA level. Intensified lipoperoxidation and increased activity of SOD and GPx were observed, regardless of the level of contamination with ZEA (300 µg/L or 900 µg/L). Increased contamination with AFB2+G1 and OTA caused an increase in the production of most HSPs tested (HSP31, HSP40, HSP70, HSP104). ZEA contamination in the used concentration ranges reduced the production of HSP31. The response of yeast cells to the presence of mycotoxin as a stressor resulted in the expression of certain HSPs, but the response was not systematic, which was manifested in different profiles of protein expression depending on the mycotoxin used. The tested mycotoxins influenced the induction of oxidative stress in yeast cells to varying degrees, which resulted in the activation of mainly SOD without GST mobilization or with a small involvement of GPx.
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Affiliation(s)
- Grzegorz Kłosowski
- Department of Biotechnology, Faculty of Biological Sciences, Kazimierz Wielki University, ul. K. J. Poniatowskiego 12, 85-671 Bydgoszcz, Poland (J.D.-A.); (D.M.)
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Procópio DP, Lee JW, Shin J, Tramontina R, Ávila PF, Brenelli LB, Squina FM, Damasio A, Rabelo SC, Goldbeck R, Franco TT, Leak D, Jin YS, Basso TO. Metabolic engineering of Saccharomyces cerevisiae for second-generation ethanol production from xylo-oligosaccharides and acetate. Sci Rep 2023; 13:19182. [PMID: 37932303 PMCID: PMC10628280 DOI: 10.1038/s41598-023-46293-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 10/30/2023] [Indexed: 11/08/2023] Open
Abstract
Simultaneous intracellular depolymerization of xylo-oligosaccharides (XOS) and acetate fermentation by engineered Saccharomyces cerevisiae offers significant potential for more cost-effective second-generation (2G) ethanol production. In the present work, the previously engineered S. cerevisiae strain, SR8A6S3, expressing enzymes for xylose assimilation along with an optimized route for acetate reduction, was used as the host for expressing two β-xylosidases, GH43-2 and GH43-7, and a xylodextrin transporter, CDT-2, from Neurospora crassa, yielding the engineered SR8A6S3-CDT-2-GH34-2/7 strain. Both β-xylosidases and the transporter were introduced by replacing two endogenous genes, GRE3 and SOR1, that encode aldose reductase and sorbitol (xylitol) dehydrogenase, respectively, and catalyse steps in xylitol production. The engineered strain, SR8A6S3-CDT-2-GH34-2/7 (sor1Δ gre3Δ), produced ethanol through simultaneous XOS, xylose, and acetate co-utilization. The mutant strain produced 60% more ethanol and 12% less xylitol than the control strain when a hemicellulosic hydrolysate was used as a mono- and oligosaccharide source. Similarly, the ethanol yield was 84% higher for the engineered strain using hydrolysed xylan, compared with the parental strain. Xylan, a common polysaccharide in lignocellulosic residues, enables recombinant strains to outcompete contaminants in fermentation tanks, as XOS transport and breakdown occur intracellularly. Furthermore, acetic acid is a ubiquitous toxic component in lignocellulosic hydrolysates, deriving from hemicellulose and lignin breakdown. Therefore, the consumption of XOS, xylose, and acetate expands the capabilities of S. cerevisiae for utilization of all of the carbohydrate in lignocellulose, potentially increasing the efficiency of 2G biofuel production.
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Affiliation(s)
- Dielle Pierotti Procópio
- Department of Chemical Engineering, Escola Politécnica, Universidade de São Paulo (USP), São Paulo, SP, 05508-010, Brazil
- Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo), São Paulo, SP, 05508-900, Brazil
| | - Jae Won Lee
- DOE Center for Advanced Bioenergy and Bioproducts Innovation (CABER), University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign (UIUC), Urbana, IL, 61801, USA
| | - Jonghyeok Shin
- DOE Center for Advanced Bioenergy and Bioproducts Innovation (CABER), University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign (UIUC), Urbana, IL, 61801, USA
- Synthetic Biology & Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Republic of Korea
| | - Robson Tramontina
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083-862, Brazil
- Environment and Technological Processes Program, University of Sorocaba (UNISO), Sorocaba, SP, 18023-000, Brazil
| | - Patrícia Felix Ávila
- School of Food Engineering, University of Campinas (UNICAMP), Campinas, SP, 13083-862, Brazil
| | - Lívia Beatriz Brenelli
- Interdisciplinary Centre of Energy Planning, University of Campinas (UNICAMP), Campinas, SP, 13083-896, Brazil
| | - Fabio Márcio Squina
- Environment and Technological Processes Program, University of Sorocaba (UNISO), Sorocaba, SP, 18023-000, Brazil
| | - André Damasio
- Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, SP, 13083-862, Brazil
| | - Sarita Cândida Rabelo
- Departament of Bioprocesses and Biotechnology, School of Agriculture, Sao Paulo State University (UNESP), Botucatu, SP, 18618-687, Brazil
| | - Rosana Goldbeck
- School of Food Engineering, University of Campinas (UNICAMP), Campinas, SP, 13083-862, Brazil
| | - Telma Teixeira Franco
- Interdisciplinary Centre of Energy Planning, University of Campinas (UNICAMP), Campinas, SP, 13083-896, Brazil
- School of Chemical Engineering, University of Campinas (UNICAMP), Campinas, SP, 13083-852, Brazil
| | - David Leak
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Yong-Su Jin
- DOE Center for Advanced Bioenergy and Bioproducts Innovation (CABER), University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign (UIUC), Urbana, IL, 61801, USA
| | - Thiago Olitta Basso
- Department of Chemical Engineering, Escola Politécnica, Universidade de São Paulo (USP), São Paulo, SP, 05508-010, Brazil.
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Fernandes MA, Mota MN, Faria NT, Sá-Correia I. An Evolved Strain of the Oleaginous Yeast Rhodotorula toruloides, Multi-Tolerant to the Major Inhibitors Present in Lignocellulosic Hydrolysates, Exhibits an Altered Cell Envelope. J Fungi (Basel) 2023; 9:1073. [PMID: 37998878 PMCID: PMC10672028 DOI: 10.3390/jof9111073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 10/24/2023] [Accepted: 10/31/2023] [Indexed: 11/25/2023] Open
Abstract
The presence of toxic compounds in lignocellulosic hydrolysates (LCH) is among the main barriers affecting the efficiency of lignocellulose-based fermentation processes, in particular, to produce biofuels, hindering the production of intracellular lipids by oleaginous yeasts. These microbial oils are promising sustainable alternatives to vegetable oils for biodiesel production. In this study, we explored adaptive laboratory evolution (ALE), under methanol- and high glycerol concentration-induced selective pressures, to improve the robustness of a Rhodotorula toruloides strain, previously selected to produce lipids from sugar beet hydrolysates by completely using the major C (carbon) sources present. An evolved strain, multi-tolerant not only to methanol but to four major inhibitors present in LCH (acetic acid, formic acid, hydroxymethylfurfural, and furfural) was isolated and the mechanisms underlying such multi-tolerance were examined, at the cellular envelope level. Results indicate that the evolved multi-tolerant strain has a cell wall that is less susceptible to zymolyase and a decreased permeability, based on the propidium iodide fluorescent probe, in the absence or presence of those inhibitors. The improved performance of this multi-tolerant strain for lipid production from a synthetic lignocellulosic hydrolysate medium, supplemented with those inhibitors, was confirmed.
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Affiliation(s)
- Mónica A. Fernandes
- iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
- i4HB—Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
| | - Marta N. Mota
- iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
- i4HB—Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
| | - Nuno T. Faria
- iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
- i4HB—Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
| | - Isabel Sá-Correia
- iBB—Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
- i4HB—Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisbon, Portugal
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Mikulski D, Kłosowski G. High-pressure microwave-assisted pretreatment of softwood, hardwood and non-wood biomass using different solvents in the production of cellulosic ethanol. Biotechnol Biofuels Bioprod 2023; 16:19. [PMID: 36750940 PMCID: PMC9906915 DOI: 10.1186/s13068-023-02272-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 01/29/2023] [Indexed: 02/09/2023]
Abstract
BACKGROUND Pretreatment is an indispensable stage of the preparation of lignocellulosic biomass with key significance for the effectiveness of hydrolysis and the efficiency of the production of cellulosic ethanol. A significant increase in the susceptibility of the raw material to further degradation can be attained as a result of effective delignification in high-pressure conditions. With this in mind, a method of high-pressure pretreatment using microwave radiation and various solvents (water, 40% w/v NaCS, 1% v/v H2SO4, 1% w/v NaOH or 60% v/v EtOH with an addition of 1% v/v H2SO4) was developed, enabling the acquisition of biomass with an increased susceptibility to the process of enzymatic hydrolysis. The medium obtained in this way can be used for the production of cellulosic ethanol via high-gravity technology (lignocellulosic media containing from 15 to 20% dry weight of biomass). For every type of biomass (pine chips, beech chips and wheat straw), a solvent was selected to be used during the pretreatment, guaranteeing the acquisition of a medium highly susceptible to the process of enzymatic hydrolysis. RESULTS The highest efficiency of the hydrolysis of biomass, amounting to 71.14 ± 0.97% (glucose concentration 109.26 ± 3.49 g/L) was achieved for wheat straw subjected to microwave-assisted pretreatment using 40% w/v NaCS. Fermentation of this medium produced ethanol concentration at the level of 53.84 ± 1.25 g/L. A slightly lower effectiveness of enzymatic hydrolysis (62.21 ± 0.62%) was achieved after high-pressure microwave-assisted pretreatment of beech chips using 1% w/v NaOH. The hydrolysate contained glucose in the concentration of 91.78 ± 1.91 g/L, and the acquired concentration of ethanol after fermentation amounted to 49.07 ± 2.06 g/L. In the case of pine chips, the most effective delignification was achieved using 60% v/v EtOH with the addition of 1% v/v H2SO4, but after enzymatic hydrolysis, the concentration of glucose in hydrolysate was lower than in the other raw materials and amounted to 39.15 ± 1.62 g/L (the concentration of ethanol after fermentation was ca. 19.67 ± 0.98 g/L). The presence of xylose and galactose was also determined in the obtained fermentation media. The highest initial concentration of these carbohydrates (21.39 ± 1.44 g/L) was observed in beech chips media after microwave-assisted pretreatment using NaOH. The use of wheat straw after pretreatment using EtOH with an addition of 1% v/v H2SO4 for the preparation of fermentation medium, results in the generation of the initial concentration of galactose and xylose at the level of 19.03 ± 0.38 g/L. CONCLUSION The achieved results indicate a high effectiveness of the enzymatic hydrolysis of the biomass subjected to high-pressure microwave-assisted pretreatment. The final effect depends on the combined use of correctly selected solvents for the different sources of lignocellulosic biomass. On the basis of the achieved results, we can say that the presented method indicates a very high potential in the area of its use for the production of cellulosic ethanol involving high-gravity technology.
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Affiliation(s)
- Dawid Mikulski
- grid.412085.a0000 0001 1013 6065Faculty of Natural Science, Department of Biotechnology, Kazimierz Wielki University, Ul. K. J. Poniatowskiego 12, 85-671 Bydgoszcz, Poland
| | - Grzegorz Kłosowski
- Faculty of Natural Science, Department of Biotechnology, Kazimierz Wielki University, Ul. K. J. Poniatowskiego 12, 85-671, Bydgoszcz, Poland.
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Kłosowski G, Mikulski D, Bhagwat P, Pillai S. Cellulosic Ethanol Production Using Waste Wheat Stillage after Microwave-Assisted Hydrotropic Pretreatment. Molecules 2022; 27:6097. [PMID: 36144825 DOI: 10.3390/molecules27186097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022]
Abstract
One of the key elements influencing the efficiency of cellulosic ethanol production is the effective pretreatment of lignocellulosic biomass. The aim of the study was to evaluate the effect of microwave-assisted pretreatment of wheat stillage in the presence of sodium cumene sulphonate (NaCS) hydrotrope used for the production of second-generation bioethanol. As a result of microwave pretreatment, the composition of the wheat stillage biomass changed significantly when compared with the raw material used, before treatment. Microwave-assisted pretreatment with NaCS effectively reduced the lignin content and hemicellulose, making cellulose the dominant component of biomass, which accounted for 42.91 ± 0.10%. In post pretreatment, changes in biomass composition were also visible on FTIR spectra. The peaks of functional groups and bonds characteristic of lignins (C-O vibration in the syringyl ring, asymmetric bending in CH3, and aromatic skeleton C-C stretching) decreased. The pretreatment of the analyzed lignocellulosic raw material with NaCS resulted in the complete conversion of glucose to ethanol after 48 h of the process, with yield (in relation to the theoretical one) of above 91%. The highest observed concentration of ethanol, 23.57 ± 0.10 g/L, indicated the high effectiveness of the method used for the pretreatment of wheat stillage that did not require additional nutrient supplementation.
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Mikulski D, Kłosowski G. Delignification efficiency of various types of biomass using microwave-assisted hydrotropic pretreatment. Sci Rep 2022; 12:4561. [PMID: 35296788 DOI: 10.1038/s41598-022-08717-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 03/02/2022] [Indexed: 11/10/2022] Open
Abstract
The use of a method of an effective delignification of lignocellulosic biomass is a key stage of designing processes of its microbiological conversion e.g. for the purposes of the production of cellulosic ethanol. The study was aimed at evaluating the effectiveness of microwave-assisted hydrotropic pretreatment using sodium cumene sulfonate (NaCS) for the delignification of pine and beech chips and wheat straw. Research results presenting the impact of process parameters of microwave-assisted hydrotropic delignification confirm a high effectiveness of this method of pretreatment of lignocellulosic biomass. The observed effects included changes in the composition of the biomass and an increased susceptibility of cellulose to the subsequent enzymatic hydrolysis. The use of microwave heating combined with an addition of hydrotrope of 40% w/v NaCS and 117 PSI for 60 min enabled a reduction of the absolute concentration of lignins by 36.58% in pine chips, by 57.68% in beech chips, and by 74.08% in wheat straw. After enzymatic hydrolysis was conducted, the highest concentration of glucose: 463.27 ± 11.25 mg glucose/g (hydrolysis yield 46.76 ± 1.14%) was obtained from the wheat straw, while 327.70 ± 22.15 mg glucose/g (hydrolysis yield 35.13 ± 2.37%) was acquired from the beech chips, and only 50.77 ± 0.75 mg glucose/g (hydrolysis yield 6.63 ± 0.10%) was obtained from the pine chips. Microwave-assisted hydrotropic delignification in the optimum process conditions additionally allows a complete removal of hemicellulose from biomass, which improves the effectiveness of enzymatic hydrolysis. Due to a significant reduction of lignin and hemicellulose concentration in biomass, cellulose—which is susceptible to enzymatic hydrolysis and a source of carbon in biosynthesis processes—becomes the main biomass component.
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