1
|
Wu Z, Li P, Chen X, Feng Y, Ma Y, Ni Z, Zhu D, Chen H. Surface display system of Bacillus subtilis: A promising approach for improving the stability and applications of cellobiose dehydrogenase. Protein Expr Purif 2024; 218:106448. [PMID: 38373510 DOI: 10.1016/j.pep.2024.106448] [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: 12/05/2023] [Revised: 02/16/2024] [Accepted: 02/16/2024] [Indexed: 02/21/2024]
Abstract
Cellobiose dehydrogenase (CDH) plays a crucial role in lignocellulose degradation and bioelectrochemical industries, making it highly in demand. However, the production and purification of CDH through fungal heterologous expression methods is time-consuming, costly, and challenging. In this study, we successfully displayed Pycnoporus sanguineus CDH (psCDH) on the surface of Bacillus subtilis spores for the first time. Enzymatic characterization revealed that spore surface display enhanced the tolerance of psCDH to high temperature (80 °C) and low pH levels (3.5) compared to free psCDH. Furthermore, we found that glycerol, lactic acid, and malic acid promoted the activity of immobilized spore-displayed psCDH; glycerol has a more significant stimulating effect, increasing the activity from 16.86 ± 1.27 U/mL to 46.26 ± 3.25 U/mL. After four reuse cycles, the psCDH immobilized with spores retained 48% of its initial activity, demonstrating a substantial recovery rate. In conclusion, the spore display system, relying on cotG, enables the expression and immobilization of CDH while enhancing its resistance to adverse conditions. This system demonstrates efficient enzyme recovery and reuse. This approach provides a novel method and strategy for the immobilization and stability enhancement of CDH.
Collapse
Affiliation(s)
- Zhengfen Wu
- School of Life Sciences, Jiangsu University, Jiangsu, Zhenjiang, 212013, China
| | - Pengfei Li
- School of Life Sciences, Jiangsu University, Jiangsu, Zhenjiang, 212013, China
| | - Xihua Chen
- School of Life Sciences, Jiangsu University, Jiangsu, Zhenjiang, 212013, China
| | - Yong Feng
- School of Life Sciences, Jiangsu University, Jiangsu, Zhenjiang, 212013, China
| | - Yi Ma
- School of Life Sciences, Jiangsu University, Jiangsu, Zhenjiang, 212013, China
| | - Zhong Ni
- School of Life Sciences, Jiangsu University, Jiangsu, Zhenjiang, 212013, China
| | - Daochen Zhu
- School of Life Sciences, Jiangsu University, Jiangsu, Zhenjiang, 212013, China
| | - Huayou Chen
- School of Life Sciences, Jiangsu University, Jiangsu, Zhenjiang, 212013, China.
| |
Collapse
|
2
|
Grace Barrios-Gutiérrez S, Inés Vélez-Mercado M, Rodrigues Ortega J, da Silva Lima A, Luiza da Rocha Fortes Saraiva A, Leila Berto G, Segato F. Oxidative Machinery of basidiomycetes as potential enhancers in lignocellulosic biorefineries: A lytic polysaccharide monooxygenases approach. BIORESOURCE TECHNOLOGY 2023; 386:129481. [PMID: 37437815 DOI: 10.1016/j.biortech.2023.129481] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/05/2023] [Accepted: 07/08/2023] [Indexed: 07/14/2023]
Abstract
Basidiomycetes are renowned as highly effective decomposers of plant materials, due to their extensive array of oxidative enzymes, which enable them to efficiently break down complex lignocellulosic biomass structures. Among the oxidative machinery of industrially relevant basidiomycetes, the role of lytic polysaccharide monooxygenases (LPMO) in lignocellulosic biomass deconstruction is highlighted. So far, only a limited number of basidiomycetes LPMOs have been identified and heterologously expressed. These LPMOs have presented activity on cellulose and hemicellulose, as well as participation in the deconstruction of lignin. Expanding on this, the current review proposes both enzymatic and non-enzymatic mechanisms of LPMOs for biomass conversion, considering the significance of the Carbohydrate-Binding Modules and other C-terminal regions domains associated with their structure, which is involved in the deconstruction of lignocellulosic biomass.
Collapse
Affiliation(s)
- Solange Grace Barrios-Gutiérrez
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Martha Inés Vélez-Mercado
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Júlia Rodrigues Ortega
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Awana da Silva Lima
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Ana Luiza da Rocha Fortes Saraiva
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Gabriela Leila Berto
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Fernando Segato
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil.
| |
Collapse
|
3
|
Molecular cloning, characterisation and expression of a gene encoding cellobiose dehydrogenase from Termitomyces clypeatus. GENE REPORTS 2021. [DOI: 10.1016/j.genrep.2021.101063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
4
|
Kerdraon L, Balesdent MH, Barret M, Laval V, Suffert F. Crop Residues in Wheat-Oilseed Rape Rotation System: a Pivotal, Shifting Platform for Microbial Meetings. MICROBIAL ECOLOGY 2019; 77:931-945. [PMID: 30834960 DOI: 10.1007/s00248-019-01340-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 02/05/2019] [Indexed: 05/13/2023]
Abstract
Crop residues are a crucial ecological niche with a major biological impact on agricultural ecosystems. In this study, we used a combined diachronic and synchronic field experiment based on wheat-oilseed rape rotations to test the hypothesis that plant is a structuring factor of microbial communities in crop residues, and that this effect decreases over time with their likely progressive degradation and colonisation by other microorganisms. We characterised an entire fungal and bacterial community associated with 150 wheat and oilseed rape residue samples at a plurennial scale by metabarcoding. The impact of plant species on the residue microbiota decreased over time and our data revealed turnover, with the replacement of oligotrophs, often plant-specific genera (such as pathogens) by copiotrophs, belonging to more generalist genera. Within a single cropping season, the plant-specific genera and species were gradually replaced by taxa that are likely to originate from the soil. These changes occurred more rapidly for bacteria than for fungi, known to degrade complex compounds. Overall, our findings suggest that crop residues constitute a key fully-fledged microbial ecosystem. Taking into account this ecosystem, that has been neglected for too long, is essential, not only to improve the quantitative management of residues, the presence of which can be detrimental to crop health, but also to identify groups of beneficial microorganisms. Our findings are of particular importance, because the wheat-oilseed rape rotation, in which no-till practices are frequent, is particularly widespread in the European arable cropping systems.
Collapse
Affiliation(s)
- Lydie Kerdraon
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850, Thiverval-Grignon, France
| | - Marie-Hélène Balesdent
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850, Thiverval-Grignon, France
| | - Matthieu Barret
- UMR IRHS, INRA, Agrocampus Ouest, Université d'Angers, 49071, Beaucouzé, France
| | - Valérie Laval
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850, Thiverval-Grignon, France.
| | - Frédéric Suffert
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850, Thiverval-Grignon, France.
| |
Collapse
|
5
|
Meier KK, Jones SM, Kaper T, Hansson H, Koetsier MJ, Karkehabadi S, Solomon EI, Sandgren M, Kelemen B. Oxygen Activation by Cu LPMOs in Recalcitrant Carbohydrate Polysaccharide Conversion to Monomer Sugars. Chem Rev 2018; 118:2593-2635. [PMID: 29155571 PMCID: PMC5982588 DOI: 10.1021/acs.chemrev.7b00421] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Natural carbohydrate polymers such as starch, cellulose, and chitin provide renewable alternatives to fossil fuels as a source for fuels and materials. As such, there is considerable interest in their conversion for industrial purposes, which is evidenced by the established and emerging markets for products derived from these natural polymers. In many cases, this is achieved via industrial processes that use enzymes to break down carbohydrates to monomer sugars. One of the major challenges facing large-scale industrial applications utilizing natural carbohydrate polymers is rooted in the fact that naturally occurring forms of starch, cellulose, and chitin can have tightly packed organizations of polymer chains with low hydration levels, giving rise to crystalline structures that are highly recalcitrant to enzymatic degradation. The topic of this review is oxidative cleavage of carbohydrate polymers by lytic polysaccharide mono-oxygenases (LPMOs). LPMOs are copper-dependent enzymes (EC 1.14.99.53-56) that, with glycoside hydrolases, participate in the degradation of recalcitrant carbohydrate polymers. Their activity and structural underpinnings provide insights into biological mechanisms of polysaccharide degradation.
Collapse
Affiliation(s)
- Katlyn K. Meier
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Stephen M. Jones
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Thijs Kaper
- DuPont Industrial Biosciences, 925 Page Mill Road, Palo Alto, California 94304, United States
| | - Henrik Hansson
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
| | - Martijn J. Koetsier
- DuPont Industrial Biosciences, Netherlands, Nieuwe Kanaal 7-S, 6709 PA Wageningen, The Netherlands
| | - Saeid Karkehabadi
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
| | - Bradley Kelemen
- DuPont Industrial Biosciences, 925 Page Mill Road, Palo Alto, California 94304, United States
| |
Collapse
|
6
|
Chen K, Liu X, Long L, Ding S. Cellobiose dehydrogenase from Volvariella volvacea and its effect on the saccharification of cellulose. Process Biochem 2017. [DOI: 10.1016/j.procbio.2017.05.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
7
|
Mäkelä MR, Bouzid O, Robl D, Post H, Peng M, Heck A, Altelaar M, de Vries RP. Cultivation of Podospora anserina on soybean hulls results in an efficient enzyme cocktail for plant biomass hydrolysis. N Biotechnol 2017; 37:162-171. [PMID: 28188936 DOI: 10.1016/j.nbt.2017.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/06/2017] [Accepted: 02/06/2017] [Indexed: 11/25/2022]
Abstract
The coprophilic ascomycete fungus Podospora anserina was cultivated on three different plant biomasses, i.e. cotton seed hulls (CSH), soybean hulls (SBH) and acid-pretreated wheat straw (WS) for four days, and the potential of the produced enzyme mixtures was compared in the enzymatic saccharification of the corresponding lignocellulose feedstocks. The enzyme cocktail P. anserina produced after three days of growth on SBH showed superior capacity to release reducing sugars from all tested plant biomass feedstocks compared to the enzyme mixtures from CSH and WS cultures. Detailed proteomics analysis of the culture supernatants revealed that SBH contained the most diverse set of enzymes targeted on plant cell wall polymers and was particularly abundant in xylan, mannan and pectin acting enzymes. The importance of lytic polysaccharide monooxygenases (LPMOs) in plant biomass deconstruction was supported by identification of 20 out of 33 AA9 LPMOs in the SBH cultures. The results highlight the suitability of P. anserina as a source of plant cell wall degrading enzymes for biotechnological applications and the importance of selecting the most optimal substrate for the production of enzyme mixtures.
Collapse
Affiliation(s)
- Miia R Mäkelä
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands; Department of Food and Environmental Sciences, Division of Microbiology and Biotechnology, P.O. Box 56, Viikinkaari 9, University of Helsinki, Helsinki, Finland, Finland
| | - Ourdia Bouzid
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands; Microbiology, Utrecht University, Padualaan 8, 3584 Ch Utrecht, The Netherlands
| | - Diogo Robl
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands; Brazilian Laboratory of Science and Technology of Bioethanol, Giuseppe Maximo Scolfaro 10.000, Campinas, Brazil
| | - Harm Post
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecules Research and Utrecht Institute for Pharmaceutical Sciences, Padualaan 8, 3584 CH Utrecht, The Netherlands; Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Mao Peng
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands
| | - Albert Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecules Research and Utrecht Institute for Pharmaceutical Sciences, Padualaan 8, 3584 CH Utrecht, The Netherlands; Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecules Research and Utrecht Institute for Pharmaceutical Sciences, Padualaan 8, 3584 CH Utrecht, The Netherlands; Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Ronald P de Vries
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT, Utrecht, The Netherlands; Microbiology, Utrecht University, Padualaan 8, 3584 Ch Utrecht, The Netherlands.
| |
Collapse
|
8
|
Ma S, Preims M, Piumi F, Kappel L, Seiboth B, Record E, Kracher D, Ludwig R. Molecular and catalytic properties of fungal extracellular cellobiose dehydrogenase produced in prokaryotic and eukaryotic expression systems. Microb Cell Fact 2017; 16:37. [PMID: 28245812 PMCID: PMC5331742 DOI: 10.1186/s12934-017-0653-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 02/25/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Cellobiose dehydrogenase (CDH) is an extracellular enzyme produced by lignocellulolytic fungi. cdh gene expression is high in cellulose containing media, but relatively low CDH concentrations are found in the supernatant of fungal cultures due to strong binding to cellulose. Therefore, heterologous expression of CDH in Pichia pastoris was employed in the last 15 years, but the obtained enzymes were over glycosylated and had a reduced specific activity. RESULTS We compare the well-established CDH expression host P. pastoris with the less frequently used hosts Escherichia coli, Aspergillus niger, and Trichoderma reesei. The study evaluates the produced quantity and protein homogeneity of Corynascus thermophilus CDH in the culture supernatants, the purification, and finally compares the enzymes in regard to cofactor loading, glycosylation, catalytic constants and thermostability. CONCLUSIONS Whereas E. coli could only express the catalytic dehydrogenase domain of CDH, all eukaryotic hosts could express full length CDH including the cytochrome domain. The CDH produced by T. reesei was most similar to the CDH originally isolated from the fungus C. thermophilus in regard to glycosylation, cofactor loading and catalytic constants. Under the tested experimental conditions the fungal expression hosts produce CDH of superior quality and uniformity compared to P. pastoris.
Collapse
Affiliation(s)
- Su Ma
- Department of Food Sciences and Technology, Vienna Institute of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria
| | - Marita Preims
- Department of Food Sciences and Technology, Vienna Institute of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria
| | - François Piumi
- UMR BDR, INRA, ENVA, Université Paris Saclay, 78350, Jouy en Josas, France
| | - Lisa Kappel
- Research Area Biochemical Technology, Institute of Chemical Engineering, TU Wien, Gumpendorferstrasse 1a, Vienna, Austria
| | - Bernhard Seiboth
- Research Area Biochemical Technology, Institute of Chemical Engineering, TU Wien, Gumpendorferstrasse 1a, Vienna, Austria
| | - Eric Record
- Aix Marseille Université, INRA, BBF (Biodiversité et Biotechnologie Fongiques), Marseille, France
| | - Daniel Kracher
- Department of Food Sciences and Technology, Vienna Institute of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria
| | - Roland Ludwig
- Department of Food Sciences and Technology, Vienna Institute of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Vienna, Austria.
| |
Collapse
|
9
|
Inactivation of Cellobiose Dehydrogenases Modifies the Cellulose Degradation Mechanism of Podospora anserina. Appl Environ Microbiol 2016; 83:AEM.02716-16. [PMID: 27836848 DOI: 10.1128/aem.02716-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 11/04/2016] [Indexed: 12/24/2022] Open
Abstract
Conversion of biomass into high-value products, including biofuels, is of great interest to developing sustainable biorefineries. Fungi are an inexhaustible source of enzymes to degrade plant biomass. Cellobiose dehydrogenases (CDHs) play an important role in the breakdown through synergistic action with fungal lytic polysaccharide monooxygenases (LPMOs). The three CDH genes of the model fungus Podospora anserina were inactivated, resulting in single and multiple CDH mutants. We detected almost no difference in growth and fertility of the mutants on various lignocellulose sources, except on crystalline cellulose, on which a 2-fold decrease in fertility of the mutants lacking P. anserina CDH1 (PaCDH1) and PaCDH2 was observed. A striking difference between wild-type and mutant secretomes was observed. The secretome of the mutant lacking all CDHs contained five beta-glucosidases, whereas the wild type had only one. P. anserina seems to compensate for the lack of CDH with secretion of beta-glucosidases. The addition of P. anserina LPMO to either the wild-type or mutant secretome resulted in improvement of cellulose degradation in both cases, suggesting that other redox partners present in the mutant secretome provided electrons to LPMOs. Overall, the data showed that oxidative degradation of cellulosic biomass relies on different types of mechanisms in fungi. IMPORTANCE Plant biomass degradation by fungi is a complex process involving dozens of enzymes. The roles of each enzyme or enzyme class are not fully understood, and utilization of a model amenable to genetic analysis should increase the comprehension of how fungi cope with highly recalcitrant biomass. Here, we report that the cellobiose dehydrogenases of the model fungus Podospora anserina enable it to consume crystalline cellulose yet seem to play a minor role on actual substrates, such as wood shavings or miscanthus. Analysis of secreted proteins suggests that Podospora anserina compensates for the lack of cellobiose dehydrogenase by increasing beta-glucosidase expression and using an alternate electron donor for LPMO.
Collapse
|
10
|
Couturier M, Tangthirasunun N, Ning X, Brun S, Gautier V, Bennati-Granier C, Silar P, Berrin JG. Plant biomass degrading ability of the coprophilic ascomycete fungus Podospora anserina. Biotechnol Adv 2016; 34:976-983. [PMID: 27263000 DOI: 10.1016/j.biotechadv.2016.05.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 05/11/2016] [Accepted: 05/27/2016] [Indexed: 12/22/2022]
Abstract
The degradation of plant biomass is a major challenge towards the production of bio-based compounds and materials. As key lignocellulolytic enzyme producers, filamentous fungi represent a promising reservoir to tackle this challenge. Among them, the coprophilous ascomycete Podospora anserina has been used as a model organism to study various biological mechanisms because its genetics are well understood and controlled. In 2008, the sequencing of its genome revealed a great diversity of enzymes targeting plant carbohydrates and lignin. Since then, a large array of lignocellulose-acting enzymes has been characterized and genetic analyses have enabled the understanding of P. anserina metabolism and development on plant biomass. Overall, these research efforts shed light on P. anserina strategy to unlock recalcitrant lignocellulose deconstruction.
Collapse
Affiliation(s)
- Marie Couturier
- INRA, Aix Marseille Université, Polytech Marseille, UMR 1163, Biodiversité et Biotechnologie Fongiques, F-13288 Marseille, France
| | - Narumon Tangthirasunun
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Diderot, 35, rue Hélène Brion, F-75205 Paris, France
| | - Xie Ning
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Diderot, 35, rue Hélène Brion, F-75205 Paris, France
| | - Sylvain Brun
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Diderot, 35, rue Hélène Brion, F-75205 Paris, France
| | - Valérie Gautier
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Diderot, 35, rue Hélène Brion, F-75205 Paris, France
| | - Chloé Bennati-Granier
- INRA, Aix Marseille Université, Polytech Marseille, UMR 1163, Biodiversité et Biotechnologie Fongiques, F-13288 Marseille, France
| | - Philippe Silar
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Diderot, 35, rue Hélène Brion, F-75205 Paris, France.
| | - Jean-Guy Berrin
- INRA, Aix Marseille Université, Polytech Marseille, UMR 1163, Biodiversité et Biotechnologie Fongiques, F-13288 Marseille, France.
| |
Collapse
|
11
|
Activities of Secreted Aryl Alcohol Quinone Oxidoreductases from Pycnoporus cinnabarinus Provide Insights into Fungal Degradation of Plant Biomass. Appl Environ Microbiol 2016; 82:2411-2423. [PMID: 26873317 DOI: 10.1128/aem.03761-15] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 02/08/2016] [Indexed: 11/20/2022] Open
Abstract
Auxiliary activities family 3 subfamily 2 (AA3_2) from the CAZy database comprises various functions related to ligninolytic enzymes, such as fungal aryl alcohol oxidases (AAO) and glucose oxidases, both of which are flavoenzymes. The recent study of the Pycnoporus cinnabarinus CIRM BRFM 137 genome combined with its secretome revealed that four AA3_2 enzymes are secreted during biomass degradation. One of these AA3_2 enzymes, scf184803.g17, has recently been produced heterologously in Aspergillus niger Based on the enzyme's activity and specificity, it was assigned to the glucose dehydrogenases (PcinnabarinusGDH [PcGDH]). Here, we analyze the distribution of the other three AA3_2 enzymes (scf185002.g8, scf184611.g7, and scf184746.g13) to assess their putative functions. These proteins showed the highest homology with aryl alcohol oxidase from Pleurotus eryngii Biochemical characterization demonstrated that they were also flavoenzymes harboring flavin adenine dinucleotide (FAD) as a cofactor and able to oxidize a wide variety of phenolic and nonphenolic aryl alcohols and one aliphatic polyunsaturated primary alcohol. Though presenting homology with fungal AAOs, these enzymes exhibited greater efficiency in reducing electron acceptors (quinones and one artificial acceptor) than molecular oxygen and so were defined as aryl-alcohol:quinone oxidoreductases (AAQOs) with two enzymes possessing residual oxidase activity (PcAAQO2 and PcAAQO3). Structural comparison of PcAAQO homology models with P. eryngii AAO demonstrated a wider substrate access channel connecting the active-site cavity to the solvent, explaining the absence of activity with molecular oxygen. Finally, the ability of PcAAQOs to reduce radical intermediates generated by laccase from P. cinnabarinus was demonstrated, shedding light on the ligninolytic system of this fungus.
Collapse
|
12
|
Homologous and Heterologous Expression of Basidiomycete Genes Related to Plant Biomass Degradation. Fungal Biol 2016. [DOI: 10.1007/978-3-319-27951-0_5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
13
|
Identification of a Classical Mutant in the Industrial Host Aspergillus niger by Systems Genetics: LaeA Is Required for Citric Acid Production and Regulates the Formation of Some Secondary Metabolites. G3-GENES GENOMES GENETICS 2015; 6:193-204. [PMID: 26566947 PMCID: PMC4704718 DOI: 10.1534/g3.115.024067] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The asexual filamentous fungus Aspergillus niger is an important industrial cell factory for citric acid production. In this study, we genetically characterized a UV-generated A. niger mutant that was originally isolated as a nonacidifying mutant, which is a desirable trait for industrial enzyme production. Physiological analysis showed that this mutant did not secrete large amounts of citric acid and oxalic acid, thus explaining the nonacidifying phenotype. As traditional complementation approaches to characterize the mutant genotype were unsuccessful, we used bulk segregant analysis in combination with high-throughput genome sequencing to identify the mutation responsible for the nonacidifying phenotype. Since A. niger has no sexual cycle, parasexual genetics was used to generate haploid segregants derived from diploids by loss of whole chromosomes. We found that the nonacidifying phenotype was caused by a point mutation in the laeA gene. LaeA encodes a putative methyltransferase-domain protein, which we show here to be required for citric acid production in an A. niger lab strain (N402) and in other citric acid production strains. The unexpected link between LaeA and citric acid production could provide new insights into the transcriptional control mechanisms related to citric acid production in A. niger. Interestingly, the secondary metabolite profile of a ΔlaeA strain differed from the wild-type strain, showing both decreased and increased metabolite levels, indicating that LaeA is also involved in regulating the production of secondary metabolites. Finally, we show that our systems genetics approach is a powerful tool to identify trait mutations.
Collapse
|
14
|
Tan TC, Kracher D, Gandini R, Sygmund C, Kittl R, Haltrich D, Hällberg BM, Ludwig R, Divne C. Structural basis for cellobiose dehydrogenase action during oxidative cellulose degradation. Nat Commun 2015; 6:7542. [PMID: 26151670 PMCID: PMC4507011 DOI: 10.1038/ncomms8542] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 05/19/2015] [Indexed: 02/06/2023] Open
Abstract
A new paradigm for cellulose depolymerization by fungi focuses on an oxidative mechanism involving cellobiose dehydrogenases (CDH) and copper-dependent lytic polysaccharide monooxygenases (LPMO); however, mechanistic studies have been hampered by the lack of structural information regarding CDH. CDH contains a haem-binding cytochrome (CYT) connected via a flexible linker to a flavin-dependent dehydrogenase (DH). Electrons are generated from cellobiose oxidation catalysed by DH and shuttled via CYT to LPMO. Here we present structural analyses that provide a comprehensive picture of CDH conformers, which govern the electron transfer between redox centres. Using structure-based site-directed mutagenesis, rapid kinetics analysis and molecular docking, we demonstrate that flavin-to-haem interdomain electron transfer (IET) is enabled by a haem propionate group and that rapid IET requires a closed CDH state in which the propionate is tightly enfolded by DH. Following haem reduction, CYT reduces LPMO to initiate oxygen activation at the copper centre and subsequent cellulose depolymerization.
Collapse
Affiliation(s)
- Tien-Chye Tan
- School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, Roslagstullsbacken 21, Stockholm S-10691, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheelelaboratoriet, Scheeles väg 2, Stockholm S-17177, Sweden
| | - Daniel Kracher
- Food Biotechnology Laboratory, Department of Food Science and Technology, Vienna Institute of Biotechnology (VIBT), BOKU—University of Natural Resources and Life Sciences, Muthgasse 18, Vienna A-1190, Austria
| | - Rosaria Gandini
- School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, Roslagstullsbacken 21, Stockholm S-10691, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheelelaboratoriet, Scheeles väg 2, Stockholm S-17177, Sweden
| | - Christoph Sygmund
- Food Biotechnology Laboratory, Department of Food Science and Technology, Vienna Institute of Biotechnology (VIBT), BOKU—University of Natural Resources and Life Sciences, Muthgasse 18, Vienna A-1190, Austria
| | - Roman Kittl
- Food Biotechnology Laboratory, Department of Food Science and Technology, Vienna Institute of Biotechnology (VIBT), BOKU—University of Natural Resources and Life Sciences, Muthgasse 18, Vienna A-1190, Austria
| | - Dietmar Haltrich
- Food Biotechnology Laboratory, Department of Food Science and Technology, Vienna Institute of Biotechnology (VIBT), BOKU—University of Natural Resources and Life Sciences, Muthgasse 18, Vienna A-1190, Austria
| | - B. Martin Hällberg
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm S-17177, Sweden
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg 22603, Germany; and Centre for Structural Systems Biology (CSSB), DESY-Campus, Hamburg 22603, Germany
| | - Roland Ludwig
- Food Biotechnology Laboratory, Department of Food Science and Technology, Vienna Institute of Biotechnology (VIBT), BOKU—University of Natural Resources and Life Sciences, Muthgasse 18, Vienna A-1190, Austria
| | - Christina Divne
- School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, Roslagstullsbacken 21, Stockholm S-10691, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Scheelelaboratoriet, Scheeles väg 2, Stockholm S-17177, Sweden
| |
Collapse
|
15
|
Characterization of Cellobiose Dehydrogenase from a Biotechnologically Important Cerrena unicolor Strain. Appl Biochem Biotechnol 2015; 176:1638-58. [PMID: 26003328 PMCID: PMC4515248 DOI: 10.1007/s12010-015-1667-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 05/12/2015] [Indexed: 11/30/2022]
Abstract
Cellobiose dehydrogenase (CDH), a secreted flavocytochrome produced by a number of wood-degrading fungi, was detected in the culture supernatant of a biotechnologically important strain of Cerrena unicolor grown in a modified cellulose-based liquid medium. The enzyme was purified as two active fractions: CuCDH-FAD (flavin domain) (1.51-fold) with recovery of 8.35 % and CuCDH (flavo-heme enzyme) (21.21-fold) with recovery of 73.41 %. As CDH from other wood-rotting fungi, the intact form of cellobiose dehydrogenase of C. unicolor is a monomeric protein containing one flavin and one heme b with molecular mass 97 kDa and pI = 4.55. The enzyme is glycosylated (8.2 %) mainly with mannose and glucosamine residues. Moreover, the cellobiose dehydrogenase gene cdh1 and its corresponding cDNA from the fungus C. unicolor were isolated, cloned, and characterized. The 2316-bp full-length cDNA of cdh1 encoded a mature CDH protein containing 771 amino acids preceded by a signal peptide consisting of 18 amino acids. Moreover, both active fractions were characterized in terms of kinetics, temperature and pH optima, and antioxidant properties.
Collapse
|
16
|
|
17
|
Bennati-Granier C, Garajova S, Champion C, Grisel S, Haon M, Zhou S, Fanuel M, Ropartz D, Rogniaux H, Gimbert I, Record E, Berrin JG. Substrate specificity and regioselectivity of fungal AA9 lytic polysaccharide monooxygenases secreted by Podospora anserina. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:90. [PMID: 26136828 PMCID: PMC4487207 DOI: 10.1186/s13068-015-0274-3] [Citation(s) in RCA: 170] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 06/12/2015] [Indexed: 05/02/2023]
Abstract
BACKGROUND The understanding of enzymatic polysaccharide degradation has progressed intensely in the past few years with the identification of a new class of fungal-secreted enzymes, the lytic polysaccharide monooxygenases (LPMOs) that enhance cellulose conversion. In the fungal kingdom, saprotrophic fungi display a high number of genes encoding LPMOs from family AA9 but the functional relevance of this redundancy is not fully understood. RESULTS In this study, we investigated a set of AA9 LPMOs identified in the secretomes of the coprophilous ascomycete Podospora anserina, a biomass degrader of recalcitrant substrates. Their activity was assayed on cellulose in synergy with the cellobiose dehydrogenase from the same organism. We showed that the total release of oxidized oligosaccharides from cellulose was higher for PaLPMO9A, PaLPMO9E, and PaLPMO9H that harbored a carbohydrate-binding module from the family CBM1. Investigation of their regioselective mode of action revealed that PaLPMO9A and PaLPMO9H oxidatively cleaved at both C1 and C4 positions while PaLPMO9E released only C1-oxidized products. Rapid cleavage of cellulose was observed using PaLPMO9H that was the most versatile in terms of substrate specificity as it also displayed activity on cello-oligosaccharides and β-(1,4)-linked hemicellulose polysaccharides (e.g., xyloglucan, glucomannan). CONCLUSIONS This study provides insights into the mode of cleavage and substrate specificities of fungal AA9 LPMOs that will facilitate their application for the development of future biorefineries.
Collapse
Affiliation(s)
- Chloé Bennati-Granier
- />INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy, ESIL Polytech, F-13288 Marseille, France
- />Polytech Marseille, Aix Marseille Université, F-13288 Marseille, France
| | - Sona Garajova
- />INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy, ESIL Polytech, F-13288 Marseille, France
- />Polytech Marseille, Aix Marseille Université, F-13288 Marseille, France
- />Institute of Chemistry, Slovak Academy of Sciences, 84538 Bratislava, Slovakia
| | - Charlotte Champion
- />INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy, ESIL Polytech, F-13288 Marseille, France
- />Polytech Marseille, Aix Marseille Université, F-13288 Marseille, France
| | - Sacha Grisel
- />INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy, ESIL Polytech, F-13288 Marseille, France
- />Polytech Marseille, Aix Marseille Université, F-13288 Marseille, France
| | - Mireille Haon
- />INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy, ESIL Polytech, F-13288 Marseille, France
- />Polytech Marseille, Aix Marseille Université, F-13288 Marseille, France
| | - Simeng Zhou
- />INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy, ESIL Polytech, F-13288 Marseille, France
- />Polytech Marseille, Aix Marseille Université, F-13288 Marseille, France
| | - Mathieu Fanuel
- />INRA, Plateforme BIBS, Unité de Recherche Biopolymères, Interactions, Assemblages, 44316 Nantes, France
| | - David Ropartz
- />INRA, Plateforme BIBS, Unité de Recherche Biopolymères, Interactions, Assemblages, 44316 Nantes, France
| | - Hélène Rogniaux
- />INRA, Plateforme BIBS, Unité de Recherche Biopolymères, Interactions, Assemblages, 44316 Nantes, France
| | - Isabelle Gimbert
- />INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy, ESIL Polytech, F-13288 Marseille, France
- />Polytech Marseille, Aix Marseille Université, F-13288 Marseille, France
| | - Eric Record
- />INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy, ESIL Polytech, F-13288 Marseille, France
- />Polytech Marseille, Aix Marseille Université, F-13288 Marseille, France
| | - Jean-Guy Berrin
- />INRA, UMR1163 Biodiversité et Biotechnologie Fongiques, Faculté des Sciences de Luminy, ESIL Polytech, F-13288 Marseille, France
- />Polytech Marseille, Aix Marseille Université, F-13288 Marseille, France
| |
Collapse
|
18
|
Rytioja J, Hildén K, Yuzon J, Hatakka A, de Vries RP, Mäkelä MR. Plant-polysaccharide-degrading enzymes from Basidiomycetes. Microbiol Mol Biol Rev 2014; 78:614-49. [PMID: 25428937 PMCID: PMC4248655 DOI: 10.1128/mmbr.00035-14] [Citation(s) in RCA: 220] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
SUMMARY Basidiomycete fungi subsist on various types of plant material in diverse environments, from living and dead trees and forest litter to crops and grasses and to decaying plant matter in soils. Due to the variation in their natural carbon sources, basidiomycetes have highly varied plant-polysaccharide-degrading capabilities. This topic is not as well studied for basidiomycetes as for ascomycete fungi, which are the main sources of knowledge on fungal plant polysaccharide degradation. Research on plant-biomass-decaying fungi has focused on isolating enzymes for current and future applications, such as for the production of fuels, the food industry, and waste treatment. More recently, genomic studies of basidiomycete fungi have provided a profound view of the plant-biomass-degrading potential of wood-rotting, litter-decomposing, plant-pathogenic, and ectomycorrhizal (ECM) basidiomycetes. This review summarizes the current knowledge on plant polysaccharide depolymerization by basidiomycete species from diverse habitats. In addition, these data are compared to those for the most broadly studied ascomycete genus, Aspergillus, to provide insight into specific features of basidiomycetes with respect to plant polysaccharide degradation.
Collapse
Affiliation(s)
- Johanna Rytioja
- Department of Food and Environmental Sciences, Division of Microbiology and Biotechnology, University of Helsinki, Helsinki, Finland
| | - Kristiina Hildén
- Department of Food and Environmental Sciences, Division of Microbiology and Biotechnology, University of Helsinki, Helsinki, Finland
| | - Jennifer Yuzon
- Fungal Physiology, CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands
| | - Annele Hatakka
- Department of Food and Environmental Sciences, Division of Microbiology and Biotechnology, University of Helsinki, Helsinki, Finland
| | - Ronald P de Vries
- Fungal Physiology, CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands Fungal Molecular Physiology, Utrecht University, Utrecht, The Netherlands
| | - Miia R Mäkelä
- Department of Food and Environmental Sciences, Division of Microbiology and Biotechnology, University of Helsinki, Helsinki, Finland
| |
Collapse
|
19
|
A novel glucose dehydrogenase from the white-rot fungus Pycnoporus cinnabarinus: production in Aspergillus niger and physicochemical characterization of the recombinant enzyme. Appl Microbiol Biotechnol 2014; 98:10105-18. [DOI: 10.1007/s00253-014-5891-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/11/2014] [Accepted: 06/13/2014] [Indexed: 11/26/2022]
|
20
|
Comparative analyses of Podospora anserina secretomes reveal a large array of lignocellulose-active enzymes. Appl Microbiol Biotechnol 2014; 98:7457-69. [PMID: 24695830 DOI: 10.1007/s00253-014-5698-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/14/2014] [Accepted: 03/15/2014] [Indexed: 12/13/2022]
Abstract
The genome of the coprophilous fungus Podospora anserina harbors a large and highly diverse set of putative lignocellulose-acting enzymes. In this study, we investigated the enzymatic diversity of a broad range of P. anserina secretomes induced by various carbon sources (dextrin, glucose, xylose, arabinose, lactose, cellobiose, saccharose, Avicel, Solka-floc, birchwood xylan, wheat straw, maize bran, and sugar beet pulp (SBP)). Compared with the Trichoderma reesei enzymatic cocktail, P. anserina secretomes displayed similar cellulase, xylanase, and pectinase activities and greater arabinofuranosidase, arabinanase, and galactanase activities. The secretomes were further tested for their capacity to supplement a T. reesei cocktail. Four of them improved significantly the saccharification yield of steam-exploded wheat straw up to 48 %. Fine analysis of the P. anserina secretomes produced with Avicel and SBP using proteomics revealed a large array of CAZymes with a high number of GH6 and GH7 cellulases, CE1 esterases, GH43 arabinofuranosidases, and AA1 laccase-like multicopper oxidases. Moreover, a preponderance of AA9 (formerly GH61) was exclusively produced in the SBP condition. This study brings additional insights into the P. anserina enzymatic machinery and will facilitate the selection of promising targets for the development of future biorefineries.
Collapse
|
21
|
Dimarogona M, Topakas E, Christakopoulos P. Recalcitrant polysaccharide degradation by novel oxidative biocatalysts. Appl Microbiol Biotechnol 2013; 97:8455-65. [PMID: 23995228 DOI: 10.1007/s00253-013-5197-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 08/09/2013] [Accepted: 08/12/2013] [Indexed: 12/13/2022]
Abstract
The classical hydrolytic mechanism for the degradation of plant polysaccharides by saprophytic microorganisms has been reconsidered after the recent landmark discovery of a new class of oxidases termed lytic polysaccharide monooxygenases (LPMOs). LPMOs are of increased biotechnological interest due to their implication in lignocellulosic biomass decomposition for the production of biofuels and high-value chemicals. They act on recalcitrant polysaccharides by a combination of hydrolytic and oxidative function, generating oxidized and non-oxidized chain ends. They are copper-dependent and require molecular oxygen and an external electron donor for their proper function. In this review, we present the recent findings concerning the mechanism of action of these oxidative enzymes and identify issues and questions to be addressed in the future.
Collapse
Affiliation(s)
- Maria Dimarogona
- Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str, Zografou Campus, 15700, Athens, Greece
| | | | | |
Collapse
|
22
|
|
23
|
Dimarogona M, Topakas E, Christakopoulos P. Cellulose degradation by oxidative enzymes. Comput Struct Biotechnol J 2012; 2:e201209015. [PMID: 24688656 PMCID: PMC3962083 DOI: 10.5936/csbj.201209015] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 10/24/2012] [Accepted: 10/29/2012] [Indexed: 11/22/2022] Open
Abstract
Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs), cellobiose dehydrogenases (CDHs) and members of carbohydrate-binding module family 33 (CBM33). PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future.
Collapse
Affiliation(s)
- Maria Dimarogona
- BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str, Zografou Campus, 15700, Athens, Greece
| | - Evangelos Topakas
- BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str, Zografou Campus, 15700, Athens, Greece
| | - Paul Christakopoulos
- Biochemical and Chemical Process Engineering, Division of Sustainable Process Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology,SE-97187Luleå, Sweden
| |
Collapse
|