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Egbewale SO, Kumar A, Mokoena MP, Olaniran AO. Purification, characterization and three-dimensional structure prediction of multicopper oxidase Laccases from Trichoderma lixii FLU1 and Talaromyces pinophilus FLU12. Sci Rep 2024; 14:13371. [PMID: 38862560 PMCID: PMC11167041 DOI: 10.1038/s41598-024-63959-z] [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: 03/04/2024] [Accepted: 06/04/2024] [Indexed: 06/13/2024] Open
Abstract
Broad-spectrum biocatalysts enzymes, Laccases, have been implicated in the complete degradation of harmful pollutants into less-toxic compounds. In this study, two extracellularly produced Laccases were purified to homogeneity from two different Ascomycetes spp. Trichoderma lixii FLU1 (TlFLU1) and Talaromyces pinophilus FLU12 (TpFLU12). The purified enzymes are monomeric units, with a molecular mass of 44 kDa and 68.7 kDa for TlFLU1 and TpFLU12, respectively, on SDS-PAGE and zymogram. It reveals distinct properties beyond classic protein absorption at 270-280 nm, with TlFLU1's peak at 270 nm aligning with this typical range of type II Cu site (white Laccase), while TpFLU12's unique 600 nm peak signifies a type I Cu2+ site (blue Laccase), highlighting the diverse spectral fingerprints within the Laccase family. The Km and kcat values revealed that ABTS is the most suitable substrate as compared to 2,6-dimethoxyphenol, caffeic acid and guaiacol for both Laccases. The bioinformatics analysis revealed critical His, Ile, and Arg residues for copper binding at active sites, deviating from the traditional two His and a Cys motif in some Laccases. The predicted biological functions of the Laccases include oxidation-reduction, lignin metabolism, cellular metal ion homeostasis, phenylpropanoid catabolism, aromatic compound metabolism, cellulose metabolism, and biological adhesion. Additionally, investigation of degradation of polycyclic aromatic hydrocarbons (PAHs) by purified Laccases show significant reductions in residual concentrations of fluoranthene and anthracene after a 96-h incubation period. TlFLU1 Laccase achieved 39.0% and 44.9% transformation of fluoranthene and anthracene, respectively, while TpFLU12 Laccase achieved 47.2% and 50.0% transformation, respectively. The enzyme structure-function relationship study provided insights into the catalytic mechanism of these Laccases for possible biotechnological and industrial applications.
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Affiliation(s)
- Samson O Egbewale
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Durban, 4001, South Africa
| | - Ajit Kumar
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Durban, 4001, South Africa
| | - Mduduzi P Mokoena
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Durban, 4001, South Africa
- Department of Pathology, School of Medicine, University of Limpopo, Private Bag X1106, Sovenga, 0727, South Africa
| | - Ademola O Olaniran
- Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Durban, 4001, South Africa.
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2
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Wang H, Qin L, Qi W, Elshobary M, Wang W, Feng P, Wang Z, Zhu S. Harmony in detoxification: Microalgae unleashing the potential of lignocellulosic pretreatment wastewater for resource utilization. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 927:171888. [PMID: 38531442 DOI: 10.1016/j.scitotenv.2024.171888] [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: 12/22/2023] [Revised: 02/28/2024] [Accepted: 03/20/2024] [Indexed: 03/28/2024]
Abstract
Lignocellulosic biomass is a pivotal renewable resource in biorefinery process, requiring pretreatment, primarily chemical pretreatment, for effective depolymerization and subsequent transformation. This process yields solid residue for saccharification and lignocellulosic pretreatment wastewater (LPW), which comprises sugars and inhibitors such as phenols and furans. This study explored the microalgal capacity to treat LPW, focusing on two key hydrolysate inhibitors: furfural and vanillin, which impact the growth of six green microalgae. Chlorella sorokiniana exhibited higher tolerance to furfural and vanillin. However, both inhibitors hindered the growth of C. sorokiniana and disrupted algal photosynthetic system, with vanillin displaying superior inhibition. A synergistic inhibitory effect (Q < 0.85) was observed with furfural and vanillin on algal growth. Furfural transformation to low-toxic furfuryl alcohol was rapid, yet the addition of vanillin hindered this process. Vanillin stimulated carbohydrate accumulation, with 50.48 % observed in the 0.1 g/L furfural + 0.1 g/L vanillin group. Additionally, vanillin enhanced the accumulation of C16: 0 and C18: 2, reaching 21.71 % and 40.36 %, respectively, with 0.1 g/L vanillin. This study proposed a microalgae-based detoxification and resource utilization approach for LPW, enhancing the comprehensive utilization of lignocellulosic components. The observed biomass modifications also suggested potential applications for biofuel production, contributing to the evolving landscape of sustainable biorefinery processes.
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Affiliation(s)
- Huiying Wang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, PR China; CAS Key Laboratory of Renewable Energy, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, PR China; University of Science and Technology of China, Hefei 230026, PR China
| | - Lei Qin
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, PR China; CAS Key Laboratory of Renewable Energy, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, PR China.
| | - Wei Qi
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, PR China; CAS Key Laboratory of Renewable Energy, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, PR China
| | - Mostafa Elshobary
- Botany and Microbiology Department, Faculty of Science, Tanta University, Tanta 31527, Egypt
| | - Wen Wang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, PR China; CAS Key Laboratory of Renewable Energy, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, PR China
| | - Pingzhong Feng
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, PR China; CAS Key Laboratory of Renewable Energy, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, PR China
| | - Zhongming Wang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, PR China; CAS Key Laboratory of Renewable Energy, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, PR China
| | - Shunni Zhu
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, PR China; CAS Key Laboratory of Renewable Energy, Guangzhou 510640, PR China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, PR China.
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3
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Fernández-Sandoval MT, García A, Teymennet-Ramírez KV, Arenas-Olivares DY, Martínez-Morales F, Trejo-Hernández MR. Removal of phenolic inhibitors from lignocellulose hydrolysates using laccases for the production of fuels and chemicals. Biotechnol Prog 2024; 40:e3406. [PMID: 37964692 DOI: 10.1002/btpr.3406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 10/14/2023] [Accepted: 10/23/2023] [Indexed: 11/16/2023]
Abstract
Lignocellulose is the most abundant biopolymer in the biosphere. It is inexpensive and therefore considered an attractive feedstock to produce biofuels and other biochemicals. Thermochemical and/or enzymatic pretreatment is used to release fermentable monomeric sugars. However, a variety of inhibitory by-products such as weak acids, furans, and phenolics that inhibit cell growth and fermentation are also released. Phenolic compounds are among the most toxic components in lignocellulosic hydrolysates and slurries derived from lignin decomposition, affecting overall fermentation processes and production yields and productivity. Ligninolytic enzymes have been shown to lower inhibitor concentrations in these hydrolysates, thereby enhancing their fermentability into valuable products. Among them, laccases, which are capable of oxidizing lignin and a variety of phenolic compounds in an environmentally benign manner, have been used for biomass delignification and detoxification of lignocellulose hydrolysates with promising results. This review discusses the state of the art of different enzymatic approaches to hydrolysate detoxification. In particular, laccases are used in separate or in situ detoxification steps, namely in free enzyme processes or immobilized by cell surface display technology to improve the efficiency of the fermentative process and consequently the production of second-generation biofuels and bio-based chemicals.
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Affiliation(s)
- M T Fernández-Sandoval
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - A García
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - K V Teymennet-Ramírez
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - D Y Arenas-Olivares
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - F Martínez-Morales
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - M R Trejo-Hernández
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
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4
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Moreno AD, González-Fernández C, Tomás-Pejó E. Insights into cell robustness against lignocellulosic inhibitors and insoluble solids in bioethanol production processes. Sci Rep 2022; 12:557. [PMID: 35017613 PMCID: PMC8752620 DOI: 10.1038/s41598-021-04554-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 12/24/2021] [Indexed: 11/28/2022] Open
Abstract
Increasing yeast robustness against lignocellulosic-derived inhibitors and insoluble solids in bioethanol production is essential for the transition to a bio-based economy. This work evaluates the effect exerted by insoluble solids on yeast tolerance to inhibitory compounds, which is crucial in high gravity processes. Adaptive laboratory evolution (ALE) was applied on a xylose-fermenting Saccharomyces cerevisiae strain to simultaneously increase the tolerance to lignocellulosic inhibitors and insoluble solids. The evolved strain gave rise to a fivefold increase in bioethanol yield in fermentation experiments with high concentration of inhibitors and 10% (w/v) of water insoluble solids. This strain also produced 5% (P > 0.01) more ethanol than the parental in simultaneous saccharification and fermentation of steam-exploded wheat straw, mainly due to an increased xylose consumption. In response to the stress conditions (solids and inhibitors) imposed in ALE, cells induced the expression of genes related to cell wall integrity (SRL1, CWP2, WSC2 and WSC4) and general stress response (e.g., CDC5, DUN1, CTT1, GRE1), simultaneously repressing genes related to protein synthesis and iron transport and homeostasis (e.g., FTR1, ARN1, FRE1), ultimately leading to the improved phenotype. These results contribute towards understanding molecular mechanisms that cells might use to convert lignocellulosic substrates effectively.
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Affiliation(s)
- Antonio D Moreno
- Advanced Biofuels and Bioproducts Unit, CIEMAT, Avda. Complutense 40, 28040, Madrid, Spain
| | - Cristina González-Fernández
- Biotechnological Processes Unit, IMDEA Energy Institute, Avda. Ramón de la Sagra 3, 28935, Móstoles, Madrid, Spain
| | - Elia Tomás-Pejó
- Biotechnological Processes Unit, IMDEA Energy Institute, Avda. Ramón de la Sagra 3, 28935, Móstoles, Madrid, Spain.
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5
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de Freitas EN, Salgado JCS, Alnoch RC, Contato AG, Habermann E, Michelin M, Martínez CA, Polizeli MDLTM. Challenges of Biomass Utilization for Bioenergy in a Climate Change Scenario. BIOLOGY 2021; 10:1277. [PMID: 34943192 PMCID: PMC8698859 DOI: 10.3390/biology10121277] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 11/29/2021] [Accepted: 11/29/2021] [Indexed: 12/01/2022]
Abstract
The climate changes expected for the next decades will expose plants to increasing occurrences of combined abiotic stresses, including drought, higher temperatures, and elevated CO2 atmospheric concentrations. These abiotic stresses have significant consequences on photosynthesis and other plants' physiological processes and can lead to tolerance mechanisms that impact metabolism dynamics and limit plant productivity. Furthermore, due to the high carbohydrate content on the cell wall, plants represent a an essential source of lignocellulosic biomass for biofuels production. Thus, it is necessary to estimate their potential as feedstock for renewable energy production in future climate conditions since the synthesis of cell wall components seems to be affected by abiotic stresses. This review provides a brief overview of plant responses and the tolerance mechanisms applied in climate change scenarios that could impact its use as lignocellulosic biomass for bioenergy purposes. Important steps of biofuel production, which might influence the effects of climate change, besides biomass pretreatments and enzymatic biochemical conversions, are also discussed. We believe that this study may improve our understanding of the plant biological adaptations to combined abiotic stress and assist in the decision-making for selecting key agronomic crops that can be efficiently adapted to climate changes and applied in bioenergy production.
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Affiliation(s)
- Emanuelle Neiverth de Freitas
- Department of Biochemistry and Immunology, Faculdade de Medicina de Ribeirão Preto (FMRP), University of São Paulo, Ribeirão Preto 14049-900, São Paulo, Brazil; (E.N.d.F.); (A.G.C.)
| | - José Carlos Santos Salgado
- Department of Chemistry, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), University of São Paulo, Ribeirão Preto 14040-901, São Paulo, Brazil;
| | - Robson Carlos Alnoch
- Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), University of São Paulo, Ribeirão Preto 14040-901, São Paulo, Brazil; (R.C.A.); (E.H.); (C.A.M.)
| | - Alex Graça Contato
- Department of Biochemistry and Immunology, Faculdade de Medicina de Ribeirão Preto (FMRP), University of São Paulo, Ribeirão Preto 14049-900, São Paulo, Brazil; (E.N.d.F.); (A.G.C.)
| | - Eduardo Habermann
- Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), University of São Paulo, Ribeirão Preto 14040-901, São Paulo, Brazil; (R.C.A.); (E.H.); (C.A.M.)
| | - Michele Michelin
- Centre of Biological Engineering (CEB), Gualtar Campus, University of Minho, 4710-057 Braga, Portugal;
| | - Carlos Alberto Martínez
- Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), University of São Paulo, Ribeirão Preto 14040-901, São Paulo, Brazil; (R.C.A.); (E.H.); (C.A.M.)
| | - Maria de Lourdes T. M. Polizeli
- Department of Biochemistry and Immunology, Faculdade de Medicina de Ribeirão Preto (FMRP), University of São Paulo, Ribeirão Preto 14049-900, São Paulo, Brazil; (E.N.d.F.); (A.G.C.)
- Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), University of São Paulo, Ribeirão Preto 14040-901, São Paulo, Brazil; (R.C.A.); (E.H.); (C.A.M.)
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6
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Malhotra M, Suman SK. Laccase-mediated delignification and detoxification of lignocellulosic biomass: removing obstacles in energy generation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:58929-58944. [PMID: 33712950 DOI: 10.1007/s11356-021-13283-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 03/01/2021] [Indexed: 06/12/2023]
Abstract
The rising global population and worldwide industrialization have led to unprecedented energy demand that is causing fast depletion of fossil reserves. This has led to search for alternative energy sources that are renewable and environment friendly. Use of lignocellulosic biomass for energy generation is considered a promising approach as it does not compete with food supply. However, the lignin component of the biomass acts as a natural barrier that prevents its efficient utilization. In order to remove the lignin and increase the amount of fermentable sugars, the lignocellulosic biomass is pretreated using physical and chemical methods which are costly and hazardous for environment. Moreover, during the traditional pretreatment process, numerous inhibitory compounds are generated that adversely affect the growth of fermentative microbes. Alternatively, biological methods that use microbes and their enzymes disrupt lignin polymers and increase the accessibility of the carbohydrates for the sugar generation. Microbial laccases have been considered as an efficient biocatalyst for delignification and detoxification offering a green initiative for energy generation process. The present review aims to bring together recent studies in bioenergy generation using laccase biocatalyst in the pretreatment processes. The work provides an overview of the sustainable and eco-friendly approach of biological delignification and detoxification through whole-cell and enzymatic methods, use of laccase-mediator system, and immobilized laccases for this purpose. It also summarizes the advantages, associated challenges, and potential prospects to overcome the limitations.
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Affiliation(s)
- Manisha Malhotra
- CSIR-Indian Institute of Petroleum, Mohkampur, Dehradun, 248005, India
| | - Sunil Kumar Suman
- CSIR-Indian Institute of Petroleum, Mohkampur, Dehradun, 248005, India.
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7
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Taherzadeh-Ghahfarokhi M, Panahi R, Mokhtarani B. Medium supplementation and thorough optimization to induce carboxymethyl cellulase production by Trichoderma reesei under solid state fermentation of nettle biomass. Prep Biochem Biotechnol 2021; 52:375-382. [PMID: 34319847 DOI: 10.1080/10826068.2021.1952599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
In the present study, the production of cellulase by Trichoderma reesei under solid-state fermentation of nettle biomass was promoted through supplementation of the culture media using carbonaceous additives and comprehensive optimization of the cultivation via the Taguchi method. CMCase activities about 5.5-6.1 U/gds were obtained by fermentation of the autoclave-pretreated biomass, among various chemical and physical pretreatments. Then, several additives including Tween 80, betaine, carboxymethyl cellulose, and lactose were individually or in combination added to the culture media to induce the enzyme production. The results proved that such additives could act as either inducers or inhibitors. Furthermore, CMCase activity surprisingly increased to 14.0 U/gds by supplementing the fermentation medium with the optimal mixture of additives including 0.08 mg/gds Tween 80, 0.4 mg/gds betaine, and 0.2 mg/gds carboxymethyl cellulose. Factor screening according to Plackett-Burman design confirmed that the levels of Urea and MgSO4 among basal medium constituents as well as pH of the medium were significantly affected CMCase production. By optimizing the levels of these factors, CMCase activity of 18.8 U/gds was obtained, which was noticeably higher than that of fermentation of the raw nettle. The applied procedure can be promisingly used to convert the nettle biomass into valuable products.
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Affiliation(s)
| | - Reza Panahi
- Chemistry & Chemical Engineering Research Center of Iran (CCERCI), Tehran, Iran
| | - Babak Mokhtarani
- Chemistry & Chemical Engineering Research Center of Iran (CCERCI), Tehran, Iran
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8
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Teymennet-Ramírez KV, Martínez-Morales F, Muñoz-Garay C, Bertrand B, Morales-Guzmán D, Trejo-Hernández MR. Laccase treatment of phenolic compounds for bioethanol production and the impact of these compounds on yeast physiology. BIOCATAL BIOTRANSFOR 2020. [DOI: 10.1080/10242422.2020.1856820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Karla V. Teymennet-Ramírez
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, México
| | - Fernando Martínez-Morales
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, México
| | - Carlos Muñoz-Garay
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México (ICF-UNAM), Cuernavaca, México
| | - Brandt Bertrand
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México (ICF-UNAM), Cuernavaca, México
| | - Daniel Morales-Guzmán
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, México
| | - María R. Trejo-Hernández
- Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Cuernavaca, México
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The roles and applications of chaotropes and kosmotropes in industrial fermentation processes. World J Microbiol Biotechnol 2020; 36:89. [PMID: 32507915 DOI: 10.1007/s11274-020-02865-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/04/2020] [Indexed: 12/13/2022]
Abstract
Chaotropicity has long been recognised as a property of some compounds. Chaotropes tend to disrupt non-covalent interactions in biological macromolecules (e.g. proteins and nucleic acids) and supramolecular assemblies (e.g. phospholipid membranes). This results in the destabilisation and unfolding of these macromolecules and assemblies. Unsurprisingly, these compounds are typically harmful to living cells since they act against multiple targets, comprising cellular integrity and function. Kosmotropes are the opposite of chaotropes and these compounds promote the ordering and rigidification of biological macromolecules and assemblies. Since many biological macromolecules have optimum levels of flexibility, kosmotropes can also inhibit their activity and can be harmful to cells. Some products of industrial fermentations, most notably alcohols, are chaotropic. This property can be a limiting factor on rates of production and yields. It has been hypothesised that the addition of kosmotropes may mitigate the chaotropicity of some fermentation products. Some microbes naturally adapt to chaotropic environments by producing kosmotropic compatible solutes. Exploitation of this in industrial fermentations has been hampered by scientific and economic issues. The cost of the kosmotropes and their removal during purification needs to be considered. We lack a complete understanding of the chemistry of chaotropicity and a robust, quantitative framework for estimating overall chaotropicities of mixtures. This makes it difficult to predict the amount of kosmotrope required to neutralise the chaotropicity. This review considers examples of industrial fermentations where chaotropicity is an issue and suggests possible mitigations.
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Adsul M, Sandhu SK, Singhania RR, Gupta R, Puri SK, Mathur A. Designing a cellulolytic enzyme cocktail for the efficient and economical conversion of lignocellulosic biomass to biofuels. Enzyme Microb Technol 2019; 133:109442. [PMID: 31874688 DOI: 10.1016/j.enzmictec.2019.109442] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 10/03/2019] [Accepted: 10/04/2019] [Indexed: 11/19/2022]
Abstract
Concerns about dwindling fossil fuels and their unfavorable environmental impacts shifted the global focus towards the development of biofuels from lignocellulosic feedstocks. The structure of this biomass is very complex due to which variety of enzymes (cellulolytic, hemicellulolytic, auxiliary/AA9) and proteins (e.g. swollenin) required for efficient deconstruction. Major impediments in large-scale commercial production of cellulosic ethanol are the cost of cellulases and inability of any single microorganism to produce all cellulolytic components in sufficient titers. In the recent past, various methods for reducing the enzyme cost during cellulosic ethanol production have been attempted. These include designing optimal synergistic enzyme blends/cocktail, having certain ratios of enzymes from different microbial sources, for efficient hydrolysis of pretreated biomass. However, the mechanisms underlying the development, strategies for production and evaluation of optimal cellulolytic cocktails still remain unclear. This article aims to explore the technical and economic benefits of using cellulolytic enzyme cocktail, basic enzymatic and non-enzymatic components required for its development and various strategies employed for efficient cellulolytic cocktail preparation. Consideration was also given to the ways of evaluation of commercially available and in-house developed cocktails. Discussion about commercially available cellulolytic cocktails, current challenges and possible avenues in the development of cellulolytic cocktails included.
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Affiliation(s)
- Mukund Adsul
- DBT-IOC Centre for Advanced Bioenergy Research, R & D Centre, Indian Oil Corporation Ltd, Sector-13, Faridabad 121007, India.
| | - Simranjeet Kaur Sandhu
- DBT-IOC Centre for Advanced Bioenergy Research, R & D Centre, Indian Oil Corporation Ltd, Sector-13, Faridabad 121007, India
| | - Reeta Rani Singhania
- DBT-IOC Centre for Advanced Bioenergy Research, R & D Centre, Indian Oil Corporation Ltd, Sector-13, Faridabad 121007, India
| | - Ravi Gupta
- DBT-IOC Centre for Advanced Bioenergy Research, R & D Centre, Indian Oil Corporation Ltd, Sector-13, Faridabad 121007, India
| | - Suresh K Puri
- DBT-IOC Centre for Advanced Bioenergy Research, R & D Centre, Indian Oil Corporation Ltd, Sector-13, Faridabad 121007, India
| | - Anshu Mathur
- DBT-IOC Centre for Advanced Bioenergy Research, R & D Centre, Indian Oil Corporation Ltd, Sector-13, Faridabad 121007, India
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Navas LE, Martínez FD, Taverna ME, Fetherolf MM, Eltis LD, Nicolau V, Estenoz D, Campos E, Benintende GB, Berretta MF. A thermostable laccase from Thermus sp. 2.9 and its potential for delignification of Eucalyptus biomass. AMB Express 2019; 9:24. [PMID: 30756202 PMCID: PMC6372703 DOI: 10.1186/s13568-019-0748-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 02/04/2019] [Indexed: 11/25/2022] Open
Abstract
Laccases are multicopper oxidases that are being studied for their potential application in pretreatment strategies of lignocellulosic feedstocks for bioethanol production. Here, we report the expression and characterization of a predicted laccase (LAC_2.9) from the thermophilic bacterial strain Thermus sp. 2.9 and investigate its capacity to delignify lignocellulosic biomass. The purified enzyme displayed a blue color typical of laccases, showed strict copper dependence and retained 80% of its activity after 16 h at 70 °C. At 60 °C, the enzyme oxidized 2,2′-azino-di-(3-ethylbenzthiazoline sulfonate) (ABTS) and 2,6-dimethoxyphenol (DMP) at optimal pH of 5 and 6, respectively. LAC_2.9 had higher substrate specificity (kcat/KM) for DMP with a calculated value that accounts for one of the highest reported for laccases. Further, the enzyme oxidized a phenolic lignin model dimer. The incubation of steam-exploded eucalyptus biomass with LAC_2.9 and 1-hydroxybenzotriazole (HBT) as mediator changed the structural properties of the lignocellulose as evidenced by Fourier transform infrared (FTIR) spectroscopy and thermo-gravimetric analysis (TGA). However, this did not increase the yield of sugars released by enzymatic saccharification. In conclusion, LAC_2.9 is a thermostable laccase with potential application in the delignification of lignocellulosic biomass.
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Giacobbe S, Piscitelli A, Raganati F, Lettera V, Sannia G, Marzocchella A, Pezzella C. Butanol production from laccase-pretreated brewer's spent grain. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:47. [PMID: 30867680 PMCID: PMC6399911 DOI: 10.1186/s13068-019-1383-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 02/20/2019] [Indexed: 05/15/2023]
Abstract
BACKGROUND Beer is the most popular alcoholic beverage worldwide. In the manufacture of beer, various by-products and residues are generated, and the most abundant (85% of total by-products) are spent grains. Thanks to its high (hemi)cellulose content (about 50% w/w dry weight), this secondary raw material is attractive for the production of second-generation biofuels as butanol through fermentation processes. RESULTS This study reports the ability of two laccase preparations from Pleurotus ostreatus to delignify and detoxify milled brewer's spent grains (BSG). Up to 94% of phenols reduction was achieved. Moreover, thanks to the mild conditions of enzymatic pretreatment, the formation of other inhibitory compounds was avoided allowing to apply the sequential enzymatic pretreatment and hydrolysis process (no filtration and washing steps between the two phases). As expected, the high detoxification and delignification yields achieved by laccase pretreatment resulted in great saccharification. As a fact, no loss of carbohydrates was observed thanks to the novel sequential strategy, and thus the totality of polysaccharides was hydrolysed into fermentable sugars. The enzymatic hydrolysate was fermented to acetone-butanol-ethanol (ABE) by Clostridium acetobutilycum obtaining about 12.6 g/L ABE and 7.83 g/L butanol within 190 h. CONCLUSIONS The applied sequential pretreatment and hydrolysis process resulted to be very effective for the milled BSG, allowing reduction of inhibitory compounds and lignin content with a consequent efficient saccharification. C. acetobutilycum was able to ferment the BSG hydrolysate with ABE yields similar to those obtained by using synthetic media. The proposed strategy reduces the amount of wastewater and the cost of the overall process. Based on the reported results, the potential production of butanol from the fermentation of BSG hydrolysate can be envisaged.
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Affiliation(s)
| | - Alessandra Piscitelli
- Biopox srl, Via Salita Arenella 9, Naples, Italy
- Dipartimento di Scienze chimiche, Università degli Studi di Napoli“Federico II”, Via Cintia 4, 80126 Naples, Italy
| | - Francesca Raganati
- Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università degli Studi di Napoli “Federico II”, P.le V. Tecchio 80, 80125 Naples, Italy
| | | | - Giovanni Sannia
- Biopox srl, Via Salita Arenella 9, Naples, Italy
- Dipartimento di Scienze chimiche, Università degli Studi di Napoli“Federico II”, Via Cintia 4, 80126 Naples, Italy
| | - Antonio Marzocchella
- Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università degli Studi di Napoli “Federico II”, P.le V. Tecchio 80, 80125 Naples, Italy
| | - Cinzia Pezzella
- Biopox srl, Via Salita Arenella 9, Naples, Italy
- Dipartimento di Scienze chimiche, Università degli Studi di Napoli“Federico II”, Via Cintia 4, 80126 Naples, Italy
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Guan ZB, Luo Q, Wang HR, Chen Y, Liao XR. Bacterial laccases: promising biological green tools for industrial applications. Cell Mol Life Sci 2018; 75:3569-3592. [PMID: 30046841 PMCID: PMC11105425 DOI: 10.1007/s00018-018-2883-z] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 06/30/2018] [Accepted: 07/19/2018] [Indexed: 11/26/2022]
Abstract
Multicopper oxidases (MCOs) are a pervasive family of enzymes that oxidize a wide range of phenolic and nonphenolic aromatic substrates, concomitantly with the reduction of dioxygen to water. MCOs are usually divided into two functional classes: metalloxidases and laccases. Given their broad substrate specificity and eco-friendliness (molecular oxygen from air as is used as the final electron acceptor and they only release water as byproduct), laccases are regarded as promising biological green tools for an array of applications. Among these laccases, those of bacterial origin have attracted research attention because of their notable advantages, including broad substrate spectrum, wide pH range, high thermostability, and tolerance to alkaline environments. This review aims to summarize the significant research efforts on the properties, mechanisms and structures, laccase-mediator systems, genetic engineering, immobilization, and biotechnological applications of the bacteria-source laccases and laccase-like enzymes, which principally include Bacillus laccases, actinomycetic laccases and some other species of bacterial laccases. In addition, these enzymes may offer tremendous potential for environmental and industrial applications.
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Affiliation(s)
- Zheng-Bing Guan
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China.
| | - Quan Luo
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Hao-Ran Wang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Yu Chen
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Xiang-Ru Liao
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
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Mohamad Ikubar MR, Abdul Manan M, Md Salleh M, Yahya A. Solid-state fermentation of oil palm frond petiole for lignin peroxidase and xylanase-rich cocktail production. 3 Biotech 2018; 8:259. [PMID: 29765817 DOI: 10.1007/s13205-018-1268-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 04/28/2018] [Indexed: 11/30/2022] Open
Abstract
In current practice, oil palm frond leaflets and stems are re-used for soil nutrient recycling, while the petioles are typically burned. Frond petioles have high commercialization value, attributed to high lignocellulose fiber content and abundant of juice containing free reducing sugars. Pressed petiole fiber is the subject of interest in this study for the production of lignocellulolytic enzyme. The initial characterization showed the combination of 0.125 mm frond particle size and 60% moisture content provided a surface area of 42.3 m2/g, porosity of 12.8%, and density of 1.2 g/cm3, which facilitated fungal solid-state fermentation. Among the several species of Aspergillus and Trichoderma tested, Aspergillus awamori MMS4 yielded the highest xylanase (109 IU/g) and cellulase (12 IU/g), while Trichoderma virens UKM1 yielded the highest lignin peroxidase (222 IU/g). Crude enzyme cocktail also contained various sugar residues, mainly glucose and xylose (0.1-0.4 g/L), from the hydrolysis of cellulose and hemicellulose. FT-IR analysis of the fermented petioles observed reduction in cellulose crystallinity (I900/1098), cellulose-lignin (I900/1511), and lignin-hemicellulose (I1511/1738) linkages. The study demonstrated successful bioconversion of chemically untreated frond petioles into lignin peroxidase and xylanase-rich enzyme cocktail under SSF condition.
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Affiliation(s)
- Mohamed Roslan Mohamad Ikubar
- 1Biorefinery Technology Laboratory, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia
| | - Musaalbakri Abdul Manan
- Biotechnology and Nanotechnology Research Centre, Malaysian Agricultural Research and Development Institute (MARDI), 43400 Serdang, Selangor Malaysia
| | - Madihah Md Salleh
- 1Biorefinery Technology Laboratory, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia
| | - Adibah Yahya
- 1Biorefinery Technology Laboratory, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia
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Liu H, Sun J, Chang JS, Shukla P. Engineering microbes for direct fermentation of cellulose to bioethanol. Crit Rev Biotechnol 2018; 38:1089-1105. [DOI: 10.1080/07388551.2018.1452891] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Hao Liu
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, China
| | - Jianliang Sun
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, China
| | - Jo-Shu Chang
- Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan, China
| | - Pratyoosh Shukla
- Enzyme Technology and Protein Bioinformatics Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, India
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Rocha-Martín J, Martínez-Bernal C, Zamorano LS, Reyes-Sosa FM, Díez García B. Inhibition of enzymatic hydrolysis of pretreated corn stover and sugar cane straw by laccases. Process Biochem 2018. [DOI: 10.1016/j.procbio.2018.01.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Kim D, Orrego D, Ximenes EA, Ladisch MR. Cellulose conversion of corn pericarp without pretreatment. BIORESOURCE TECHNOLOGY 2017; 245:511-517. [PMID: 28898851 DOI: 10.1016/j.biortech.2017.08.156] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/23/2017] [Accepted: 08/24/2017] [Indexed: 05/25/2023]
Abstract
We report enzyme hydrolysis of cellulose in unpretreated pericarp at a cellulase loading of 0.25FPU/g pericarp solids using a phenol tolerant Aspergillus niger pectinase preparation. The overall protein added was 5mg/g and gave 98% cellulose conversion in 72h. However, for double the amount of enzyme from Trichoderma reesei, which is significantly less tolerant to phenols, conversion was only 16%. The key to achieving high conversion without pretreatment is combining phenol inhibition-resistant enzymes (such as from A. niger) with unground pericarp from which release of phenols is minimal. Size reduction of the pericarp, which is typically carried out in a corn-to-ethanol process, where corn is first ground to a fine powder, causes release of highly inhibitory phenols that interfere with cellulase enzyme activity. This work demonstrates hydrolysis without pretreatment of large particulate pericarp is a viable pathway for directly producing cellulose ethanol in corn ethanol plants.
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Affiliation(s)
- Daehwan Kim
- Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907-2022, United States; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2093, United States
| | - David Orrego
- Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907-2022, United States; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2093, United States
| | - Eduardo A Ximenes
- Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907-2022, United States; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2093, United States
| | - Michael R Ladisch
- Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907-2022, United States; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2093, United States; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-2032, United States.
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De La Torre M, Martín-Sampedro R, Fillat Ú, Eugenio ME, Blánquez A, Hernández M, Arias ME, Ibarra D. Comparison of the efficiency of bacterial and fungal laccases in delignification and detoxification of steam-pretreated lignocellulosic biomass for bioethanol production. ACTA ACUST UNITED AC 2017; 44:1561-1573. [DOI: 10.1007/s10295-017-1977-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 09/05/2017] [Indexed: 11/30/2022]
Abstract
Abstract
This study evaluates the potential of a bacterial laccase from Streptomyces ipomoeae (SilA) for delignification and detoxification of steam-exploded wheat straw, in comparison with a commercial fungal laccase from Trametes villosa. When alkali extraction followed by SilA laccase treatment was applied to the water insoluble solids fraction, a slight reduction in lignin content was detected, and after a saccharification step, an increase in both glucose and xylose production (16 and 6%, respectively) was observed. These effects were not produced with T. villosa laccase. Concerning to the fermentation process, the treatment of the steam-exploded whole slurry with both laccases produced a decrease in the phenol content by up to 35 and 71% with bacterial and fungal laccases, respectively. The phenols reduction resulted in an improved performance of Saccharomyces cerevisiae during a simultaneous saccharification and fermentation (SSF) process, improving ethanol production rate. This enhancement was more marked with a presaccharification step prior to the SSF process.
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Affiliation(s)
- María De La Torre
- 0000 0004 1937 0239 grid.7159.a Departamento de Biomedicina y Biotecnología Universidad de Alcalá Autovía A-2, Km 33.600 28805 Alcalá De Henares Madrid Spain
| | | | - Úrsula Fillat
- Forestry Products Department INIA-CIFOR Ctra. de La Coruña Km 7.5 28040 Madrid Spain
| | - María E Eugenio
- Forestry Products Department INIA-CIFOR Ctra. de La Coruña Km 7.5 28040 Madrid Spain
| | - Alba Blánquez
- 0000 0004 1937 0239 grid.7159.a Departamento de Biomedicina y Biotecnología Universidad de Alcalá Autovía A-2, Km 33.600 28805 Alcalá De Henares Madrid Spain
| | - Manuel Hernández
- 0000 0004 1937 0239 grid.7159.a Departamento de Biomedicina y Biotecnología Universidad de Alcalá Autovía A-2, Km 33.600 28805 Alcalá De Henares Madrid Spain
| | - María E Arias
- 0000 0004 1937 0239 grid.7159.a Departamento de Biomedicina y Biotecnología Universidad de Alcalá Autovía A-2, Km 33.600 28805 Alcalá De Henares Madrid Spain
| | - David Ibarra
- Forestry Products Department INIA-CIFOR Ctra. de La Coruña Km 7.5 28040 Madrid Spain
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Valette N, Perrot T, Sormani R, Gelhaye E, Morel-Rouhier M. Antifungal activities of wood extractives. FUNGAL BIOL REV 2017. [DOI: 10.1016/j.fbr.2017.01.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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20
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Laccases as a Potential Tool for the Efficient Conversion of Lignocellulosic Biomass: A Review. FERMENTATION-BASEL 2017. [DOI: 10.3390/fermentation3020017] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Kim D, Ximenes EA, Nichols NN, Cao G, Frazer SE, Ladisch MR. Maleic acid treatment of biologically detoxified corn stover liquor. BIORESOURCE TECHNOLOGY 2016; 216:437-445. [PMID: 27262718 DOI: 10.1016/j.biortech.2016.05.086] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 05/20/2016] [Accepted: 05/21/2016] [Indexed: 06/05/2023]
Abstract
Elimination of microbial and enzyme inhibitors from pretreated lignocellulose is critical for effective cellulose conversion and yeast fermentation of liquid hot water (LHW) pretreated corn stover. In this study, xylan oligomers were hydrolyzed using either maleic acid or hemicellulases, and other soluble inhibitors were eliminated by biological detoxification. Corn stover at 20% (w/v) solids was LHW pretreated LHW (severity factor: 4.3). The 20% solids (w/v) pretreated corn stover derived liquor was recovered and biologically detoxified using the fungus Coniochaeta ligniaria NRRL30616. After maleic acid treatment, and using 5 filter paper units of cellulase/g glucan (8.3mg protein/g glucan), 73% higher cellulose conversion from corn stover was obtained for biodetoxified samples compared to undetoxified samples. This corresponded to 87% cellulose to glucose conversion. Ethanol production by yeast of pretreated corn stover solids hydrolysate was 1.4 times higher than undetoxified samples, with a reduction of 3h in the fermentation lag phase.
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Affiliation(s)
- Daehwan Kim
- Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907-2032, United States; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2032, United States
| | - Eduardo A Ximenes
- Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907-2032, United States; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2032, United States
| | - Nancy N Nichols
- Bioenergy Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, USDA, 1815 N. University Street, Peoria, IL 61604, United States
| | - Guangli Cao
- School of Life Science and Technology, Harbin Institute of Technology, Harbin 150001, China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150001, China
| | - Sarah E Frazer
- Bioenergy Research Unit, National Center for Agricultural Utilization Research, Agricultural Research Service, USDA, 1815 N. University Street, Peoria, IL 61604, United States
| | - Michael R Ladisch
- Laboratory of Renewable Resources Engineering, Purdue University, West Lafayette, IN 47907-2032, United States; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907-2032, United States; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907-2032, United States.
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Oliva-Taravilla A, Tomás-Pejó E, Demuez M, González-Fernández C, Ballesteros M. Phenols and lignin: Key players in reducing enzymatic hydrolysis yields of steam-pretreated biomass in presence of laccase. J Biotechnol 2015; 218:94-101. [PMID: 26684987 DOI: 10.1016/j.jbiotec.2015.11.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 10/26/2015] [Accepted: 11/10/2015] [Indexed: 11/19/2022]
Abstract
Phenols are known as inhibitors for cellulases and fermentative microorganisms in bioethanol production processes. The addition of laccases removes the phenolic compounds and subsequently reduces the lag phase of the fermentative microorganism. However, the application of laccases diminishes glucose release during the enzymatic hydrolysis. In this study a model cellulosic substrate (Sigmacell) together with lignin extract, whole steam-pretreated wheat straw (slurry) and its water insoluble solid fraction (WIS) were subjected to enzymatic hydrolysis to evaluate the effects of laccase treatment in presence of lignin and phenols. The presence of laccase in enzymatic hydrolysis of Sigmacell with lignin extract reduced glucose yield by 37% compared with assays without laccase. Furthermore, this reduction was even more marked in presence of phenols (55% reduction). Interestingly, when hydrolyzing WIS, the addition of phenols coupled with laccase treatment did not show a reduction when compared with only laccase addition. This fact suggests the key role of lignin in the hydrolysis inhibition since in WIS the ratio cellulase per gram of lignin was much lower than in Sigmacell experiments. Finally, the lower cellobiose and xylose recoveries point out that phenolic oligomers formed by laccase oxidation play important roles in the inhibition of endoglucanases, cellobiohydrolases and xylanases. To conclude, the proportion of lignin and the composition of phenols are key players in the inhibition of cellulases when the enzymatic hydrolysis is combined with laccases detoxification.
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Affiliation(s)
- Alfredo Oliva-Taravilla
- IMDEA Energy Institute, Biotechnology Processes for Energy Production Unit, 28935 Móstoles, Spain
| | - Elia Tomás-Pejó
- IMDEA Energy Institute, Biotechnology Processes for Energy Production Unit, 28935 Móstoles, Spain.
| | - Marie Demuez
- IMDEA Energy Institute, Biotechnology Processes for Energy Production Unit, 28935 Móstoles, Spain
| | | | - Mercedes Ballesteros
- IMDEA Energy Institute, Biotechnology Processes for Energy Production Unit, 28935 Móstoles, Spain; CIEMAT, Renewable Energy Division, Biofuels Unit, 28040 Madrid, Spain
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