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Wang Y, Xue P, Cao M, Yu T, Lane ST, Zhao H. Directed Evolution: Methodologies and Applications. Chem Rev 2021; 121:12384-12444. [PMID: 34297541 DOI: 10.1021/acs.chemrev.1c00260] [Citation(s) in RCA: 203] [Impact Index Per Article: 67.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Directed evolution aims to expedite the natural evolution process of biological molecules and systems in a test tube through iterative rounds of gene diversifications and library screening/selection. It has become one of the most powerful and widespread tools for engineering improved or novel functions in proteins, metabolic pathways, and even whole genomes. This review describes the commonly used gene diversification strategies, screening/selection methods, and recently developed continuous evolution strategies for directed evolution. Moreover, we highlight some representative applications of directed evolution in engineering nucleic acids, proteins, pathways, genetic circuits, viruses, and whole cells. Finally, we discuss the challenges and future perspectives in directed evolution.
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Affiliation(s)
- Yajie Wang
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Pu Xue
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Mingfeng Cao
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Tianhao Yu
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Stephan T Lane
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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2
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Müller MJ, Stachurski S, Stoffels P, Schipper K, Feldbrügge M, Büchs J. Online evaluation of the metabolic activity of Ustilago maydis on (poly)galacturonic acid. J Biol Eng 2018; 12:34. [PMID: 30574186 PMCID: PMC6299674 DOI: 10.1186/s13036-018-0128-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/03/2018] [Indexed: 11/10/2022] Open
Abstract
Background Pectin is a rather complex and highly branched polysaccharide strengthening the plant cell wall. Thus, many different pectinases are required for an efficient microbial conversion of biomass waste streams with a high pectin content like citrus peel, apple pomace or sugar beet pulp. The screening and optimization of strains growing on pectic substrates requires both, quantification of the residual substrate and an accurate determination of the enzymatic activity. Galacturonic acid, the main sugar unit of pectin, is an uncommon substrate for microbial fermentations. Thus, growth and enzyme production of the applied strain has to be characterized in detail to understand the microbial system. An essential step to reach this goal is the development of online monitoring tools. Results In this study, a method for the online determination of residual substrate was developed for the growth of the plant pathogenic fungus Ustilago maydis on pectic substrates such as galacturonic acid. To this end, an U. maydis strain was used that expressed a heterologous exo-polygalacturonase for growth on polygalacturonic acid. The growth behavior on galacturonic acid was analyzed by online measurement of the respiration activity. A method for the online prediction of the residual galacturonic acid concentration during the cultivation, based on the overall oxygen consumption, was developed and verified by offline sampling. This sensitive method was extended towards polygalacturonic acid, which is challenging to quantify via offline measurements. Finally, the enzymatic activity in the culture supernatant was calculated and the enzyme stability during the course of the cultivation was confirmed. Conclusion The introduced method can reliably predict the residual (poly)galacturonic acid concentration based on the overall oxygen consumption. Based on this method, the enzymatic activity of the culture broth of an U. maydis strain expressing a heterologous exo-polygalacturonase could be calculated. It was demonstrated that the method is especially advantageous for determination of low enzymatic activities. In future, it will be applied to U. maydis strains in which the number of produced hydrolytic enzymes is increased for more efficient degradation. Electronic supplementary material The online version of this article (10.1186/s13036-018-0128-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Markus Jan Müller
- 1AVT - Biochemical Engineering, RWTH Aachen University, Jochen Büchs, Forckenbeckstr. 51, 52074 Aachen, Germany.,Bioeconomy Science Center (BioSC), 52426 Jülich, Germany
| | - Sarah Stachurski
- 1AVT - Biochemical Engineering, RWTH Aachen University, Jochen Büchs, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Peter Stoffels
- 2Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich-Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.,Bioeconomy Science Center (BioSC), 52426 Jülich, Germany
| | - Kerstin Schipper
- 2Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich-Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.,Bioeconomy Science Center (BioSC), 52426 Jülich, Germany
| | - Michael Feldbrügge
- 2Institute for Microbiology, Cluster of Excellence on Plant Sciences, Heinrich-Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.,Bioeconomy Science Center (BioSC), 52426 Jülich, Germany
| | - Jochen Büchs
- 1AVT - Biochemical Engineering, RWTH Aachen University, Jochen Büchs, Forckenbeckstr. 51, 52074 Aachen, Germany.,Bioeconomy Science Center (BioSC), 52426 Jülich, Germany
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3
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Regestein L, Klement T, Grande P, Kreyenschulte D, Heyman B, Maßmann T, Eggert A, Sengpiel R, Wang Y, Wierckx N, Blank LM, Spiess A, Leitner W, Bolm C, Wessling M, Jupke A, Rosenbaum M, Büchs J. From beech wood to itaconic acid: case study on biorefinery process integration. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:279. [PMID: 30337958 PMCID: PMC6180396 DOI: 10.1186/s13068-018-1273-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Accepted: 09/26/2018] [Indexed: 05/28/2023]
Abstract
Renewable raw materials in sustainable biorefinery processes pose new challenges to the manufacturing routes of platform chemicals. Beside the investigations of individual unit operations, the research on process chains, leading from plant biomass to the final products like lactic acid, succinic acid, and itaconic acid is increasing. This article presents a complete process chain from wooden biomass to the platform chemical itaconic acid. The process starts with the mechanical pretreatment of beech wood, which subsequently is subjected to chemo-catalytic biomass fractionation (OrganoCat) into three phases, which comprise cellulose pulp, aqueous hydrolyzed hemicellulose, and organic lignin solutions. Lignin is transferred to further chemical valorization. The aqueous phase containing oxalic acid as well as hemi-cellulosic sugars is treated by nanofiltration to recycle the acid catalyst back to the chemo-catalytic pretreatment and to concentrate the sugar hydrolysate. In a parallel step, the cellulose pulp is enzymatically hydrolyzed to yield glucose, which-together with the pentose-rich stream-can be used as a carbon source in the fermentation. The fermentation of the sugar fraction into itaconic acid can either be performed with the established fungi Aspergillus terreus or with Ustilago maydis. Both fermentation concepts were realized and evaluated. For purification, (in situ) filtration, (in situ) extraction, and crystallization were investigated. The presented comprehensive examination and discussion of the itaconate synthesis process-as a case study-demonstrates the impact of realistic process conditions on product yield, choice of whole cell catalyst, chemocatalysts and organic solvent system, operation mode, and, finally, the selection of a downstream concept.
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Affiliation(s)
- Lars Regestein
- AVT—Bio-chemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
- Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Adolf-Reichwein-Str. 23, 07745 Jena, Germany
| | - Tobias Klement
- AVT—Bio-chemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
- Center of Molecular Transformations, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Philipp Grande
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52064 Aachen, Germany
- Institut für Bio- und Geowissenschaften, Pflanzenwissenschaften (IBG-2), Forschungszentrum Jülich, Wilhelm-Johnen-Straße, 52425 Jülich, Germany
| | - Dirk Kreyenschulte
- AVT—Bio-chemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Benedikt Heyman
- AVT—Bio-chemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Tim Maßmann
- AVT—Fluid Process Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Armin Eggert
- AVT—Fluid Process Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Robert Sengpiel
- AVT—Chemical Process Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Yumei Wang
- AVT—Enzyme Process Technology, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Nick Wierckx
- iAMB-Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52064 Aachen, Germany
| | - Lars M. Blank
- iAMB-Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52064 Aachen, Germany
| | - Antje Spiess
- AVT—Enzyme Process Technology, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
- Institut für Bioverfahrenstechnik, Technische Universität Braunschweig, Rebenring 56, 38106 Brunswick, Germany
| | - Walter Leitner
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52064 Aachen, Germany
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Carsten Bolm
- Institut für Organische Chemie, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Matthias Wessling
- AVT—Chemical Process Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Andreas Jupke
- AVT—Fluid Process Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Miriam Rosenbaum
- iAMB-Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52064 Aachen, Germany
- Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Adolf-Reichwein-Str. 23, 07745 Jena, Germany
| | - Jochen Büchs
- AVT—Bio-chemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
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Kapsokalyvas D, Wilbers A, Boogers IA, Appeldoorn MM, Kabel MA, Loos J, Van Zandvoort MA. Biomass Pretreatment and Enzymatic Hydrolysis Dynamics Analysis Based on Particle Size Imaging. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2018; 24:517-525. [PMID: 30334516 PMCID: PMC6378656 DOI: 10.1017/s1431927618015143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 07/20/2018] [Accepted: 08/18/2018] [Indexed: 06/08/2023]
Abstract
Parameters such as pretreatment method, enzyme type and concentration, determine the conversion efficiency of biomass' cellulose and hemicellulose to glucose and mainly xylose in biomass-based fuel production. Chemical quantification of these processes offers no information on the effect of enzymatic hydrolysis (EH) on particle morphology. We report on the development of a microscopy method for imaging pretreated biomass particles at different EH stages. The method was based on acquiring large field of view images, typically 20×10 mm2 containing thousands of particles. Morphology of particles with lengths between 2 μm and 5 mm could be visualized and analyzed. The particle length distribution of corn stover samples, pretreated with increasing amounts of sulfuric acid at different EH stages, was measured. Particle size was shown to be dependent on pretreatment severity and EH time. The methodology developed could offer an alternative method for characterization of EH of biomass for second generation biofuels and visualization of recalcitrant structures.
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Affiliation(s)
- Dimitrios Kapsokalyvas
- Department of Molecular Cell Biology, CARIM, GROW, Maastricht University, Maastricht, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands
| | - Arnold Wilbers
- Royal DSM N.V., Materials Science Center, Urmonderbaan 22, Geleen6167 RD, The Netherlands
| | - Ilco A.L.A. Boogers
- Royal DSM N.V., Biotechnology Center, Alexander Fleminglaan 1, 2613 AXDelft, The Netherlands
| | - Maaike M. Appeldoorn
- Royal DSM N.V., Biotechnology Center, Alexander Fleminglaan 1, 2613 AXDelft, The Netherlands
| | - Mirjam A. Kabel
- Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, Wageningen6708 WG, The Netherlands
| | - Joachim Loos
- Royal DSM N.V., Materials Science Center, Urmonderbaan 22, Geleen6167 RD, The Netherlands
| | - Marc A.M.J. Van Zandvoort
- Department of Molecular Cell Biology, CARIM, GROW, MHeNs, NUTRIM, Maastricht University, Universiteitssingel 50, Maastricht6229 ER, The Netherlands
- Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, Pauwelstrasse 30, Aachen52704, Germany
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5
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Antonov E, Schlembach I, Regestein L, Rosenbaum MA, Büchs J. Process relevant screening of cellulolytic organisms for consolidated bioprocessing. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:106. [PMID: 28450887 PMCID: PMC5402656 DOI: 10.1186/s13068-017-0790-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 04/12/2017] [Indexed: 05/28/2023]
Abstract
BACKGROUND Although the biocatalytic conversion of cellulosic biomass could replace fossil oil for the production of various compounds, it is often not economically viable due to the high costs of cellulolytic enzymes. One possibility to reduce costs is consolidated bioprocessing (CBP), integrating cellulase production, hydrolysis of cellulose, and the fermentation of the released sugars to the desired product into one process step. To establish such a process, the most suitable cellulase-producing organism has to be identified. Thereby, it is crucial to evaluate the candidates under target process conditions. In this work, the chosen model process was the conversion of cellulose to the platform chemical itaconic acid by a mixed culture of a cellulolytic fungus with Aspergillus terreus as itaconic acid producer. Various cellulase producers were analyzed by the introduced freeze assay that measures the initial carbon release rate, quantifying initial cellulase activity under target process conditions. Promising candidates were then characterized online by monitoring their respiration activity metabolizing cellulose to assess the growth and enzyme production dynamics. RESULTS The screening of five different cellulase producers with the freeze assay identified Trichoderma reesei and Penicillium verruculosum as most promising. The measurement of the respiration activity revealed a retarded induction of cellulase production for P. verruculosum but a similar cellulase production rate afterwards, compared to T. reesei. The freeze assay measurement depicted that P. verruculosum reaches the highest initial carbon release rate among all investigated cellulase producers. After a modification of the cultivation procedure, these results were confirmed by the respiration activity measurement. To compare both methods, a correlation between the measured respiration activity and the initial carbon release rate of the freeze assay was introduced. The analysis revealed that the different initial enzyme/cellulose ratios as well as a discrepancy in cellulose digestibility are the main differences between the two approaches. CONCLUSIONS With two complementary methods to quantify cellulase activity and the dynamics of cellulase production for CBP applications, T. reesei and P. verruculosum were identified as compatible candidates for the chosen model process. The presented methods can easily be adapted to screen for suitable cellulose degrading organisms for various other applications.
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Affiliation(s)
- Elena Antonov
- AVT‑Biochemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Ivan Schlembach
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Lars Regestein
- AVT‑Biochemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
| | - Miriam A. Rosenbaum
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Jochen Büchs
- AVT‑Biochemical Engineering, RWTH Aachen University, Forckenbeckstr. 51, 52074 Aachen, Germany
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6
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High-throughput strategies for the discovery and engineering of enzymes for biocatalysis. Bioprocess Biosyst Eng 2016; 40:161-180. [DOI: 10.1007/s00449-016-1690-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 10/05/2016] [Indexed: 12/16/2022]
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7
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Antonov E, Wirth S, Gerlach T, Schlembach I, Rosenbaum MA, Regestein L, Büchs J. Efficient evaluation of cellulose digestibility by Trichoderma reesei Rut-C30 cultures in online monitored shake flasks. Microb Cell Fact 2016; 15:164. [PMID: 27686382 PMCID: PMC5043636 DOI: 10.1186/s12934-016-0567-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 09/22/2016] [Indexed: 11/10/2022] Open
Abstract
Background Pretreated lignocellulosic biomass is considered as a suitable feedstock for the sustainable production of chemicals. However, the recalcitrant nature of cellulose often results in very cost-intensive overall production processes. A promising concept to reduce the costs is consolidated bioprocessing, which integrates in a single step cellulase production, cellulose hydrolysis, and fermentative conversion of produced sugars into a valuable product. This approach, however, requires assessing the digestibility of the applied celluloses and, thus, the released sugar amount during the fermentation. Since the released sugars are completely taken up by Trichoderma reesei Rut-C30 and the sugar consumption is stoichiometrically coupled to oxygen uptake, the respiration activity was measured to evaluate the digestibility of cellulose. Results The method was successfully tested on commercial cellulosic substrates identifying a correlation between the respiration activity and the crystallinity of the substrate. Pulse experiments with cellulose and cellulases suggested that the respiration activity of T. reesei on cellulose can be divided into two distinct phases, one limited by enzyme activity and one by cellulose-binding-sites. The impact of known (cellobiose, sophorose, urea, tween 80, peptone) and new (miscanthus steepwater) compounds enhancing cellulase production was evaluated. Furthermore, the influence of two different pretreatment methods, the OrganoCat and OrganoSolv process, on the digestibility of beech wood saw dust was tested. Conclusions The introduced method allows an online evaluation of cellulose digestibility in complex and non-complex cultivation media. As the measurements are performed under fermentation conditions, it is a valuable tool to test different types of cellulose for consolidated bioprocessing applications. Furthermore, the method can be applied to identify new compounds, which influence cellulase production. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0567-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Elena Antonov
- AVT‑Biochemical Engineering, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Steffen Wirth
- AVT‑Biochemical Engineering, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Tim Gerlach
- AVT‑Biochemical Engineering, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Ivan Schlembach
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Miriam A Rosenbaum
- Institute of Applied Microbiology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Lars Regestein
- AVT‑Biochemical Engineering, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Jochen Büchs
- AVT‑Biochemical Engineering, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany.
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8
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Xiao H, Bao Z, Zhao H. High Throughput Screening and Selection Methods for Directed Enzyme Evolution. Ind Eng Chem Res 2014; 54:4011-4020. [PMID: 26074668 PMCID: PMC4461044 DOI: 10.1021/ie503060a] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 10/02/2014] [Accepted: 10/03/2014] [Indexed: 02/08/2023]
Abstract
Successful
evolutionary enzyme engineering requires a high throughput
screening or selection method, which considerably increases the chance
of obtaining desired properties and reduces the time and cost. In
this review, a series of high throughput screening and selection methods
are illustrated with significant and recent examples. These high throughput
strategies are also discussed with an emphasis on compatibility with
phenotypic analysis during directed enzyme evolution. Lastly, certain
limitations of current methods, as well as future developments, are
briefly summarized.
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Affiliation(s)
- Han Xiao
- Department of Chemical and Biomolecular Engineering, Department of Biochemistry, and Departments of Chemistry and Bioengineering and Institute for Genomic Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Zehua Bao
- Department of Chemical and Biomolecular Engineering, Department of Biochemistry, and Departments of Chemistry and Bioengineering and Institute for Genomic Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering, Department of Biochemistry, and Departments of Chemistry and Bioengineering and Institute for Genomic Biology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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9
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Rostagno MA, Prado JM, Mudhoo A, Santos DT, Forster–Carneiro T, Meireles MAA. Subcritical and supercritical technology for the production of second generation bioethanol. Crit Rev Biotechnol 2014; 35:302-12. [DOI: 10.3109/07388551.2013.843155] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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10
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Prado JM, Follegatti-Romero LA, Forster-Carneiro T, Rostagno MA, Maugeri Filho F, Meireles MAA. Hydrolysis of sugarcane bagasse in subcritical water. J Supercrit Fluids 2014. [DOI: 10.1016/j.supflu.2013.11.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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11
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Engel P, Hein L, Spiess AC. Derivatization-free gel permeation chromatography elucidates enzymatic cellulose hydrolysis. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:77. [PMID: 23062284 PMCID: PMC3524663 DOI: 10.1186/1754-6834-5-77] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 10/05/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND The analysis of cellulose molecular weight distributions by gel permeation chromatography (GPC) is a powerful tool to obtain detailed information on enzymatic cellulose hydrolysis, supporting the development of economically viable biorefinery processes. Unfortunately, due to work and time consuming sample preparation, the measurement of cellulose molecular weight distributions has a limited applicability until now. RESULTS In this work we present a new method to analyze cellulose molecular weight distributions that does not require any prior cellulose swelling, activation, or derivatization. The cellulose samples were directly dissolved in dimethylformamide (DMF) containing 10-20% (v/v) 1-ethyl-3-methylimidazolium acetate (EMIM Ac) for 60 minutes, thereby reducing the sample preparation time from several days to a few hours. The samples were filtrated 0.2 μm to avoid column blocking, separated at 0.5 mL/min using hydrophilic separation media and were detected using differential refractive index/multi angle laser light scattering (dRI/MALLS). The applicability of this method was evaluated for the three cellulose types Avicel, α-cellulose and Sigmacell. Afterwards, this method was used to measure the changes in molecular weight distributions during the enzymatic hydrolysis of the different untreated and ionic liquid pretreated cellulose substrates. The molecular weight distributions showed a stronger shift to smaller molecular weights during enzymatic hydrolysis using a commercial cellulase preparation for cellulose with lower crystallinity. This was even more pronounced for ionic liquid-pretreated cellulose. CONCLUSIONS In conclusion, this strongly simplified GPC method for cellulose molecular weight distribution allowed for the first time to demonstrate the influence of cellulose properties and pretreatment on the mode of enzymatic hydrolysis.
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Affiliation(s)
- Philip Engel
- AVT-Enzyme Process Technology, RWTH Aachen University, Worringerweg 1, Aachen, 52056, Germany
| | - Lea Hein
- AVT-Enzyme Process Technology, RWTH Aachen University, Worringerweg 1, Aachen, 52056, Germany
| | - Antje C Spiess
- AVT-Enzyme Process Technology, RWTH Aachen University, Worringerweg 1, Aachen, 52056, Germany
- Interactive Materials Research, DWI an der RWTH Aachen e.V, Forckenbeckstr. 50, Aachen, 52074, Germany
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12
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Jäger G, Büchs J. Biocatalytic conversion of lignocellulose to platform chemicals. Biotechnol J 2012; 7:1122-36. [DOI: 10.1002/biot.201200033] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Revised: 05/17/2012] [Accepted: 06/08/2012] [Indexed: 01/12/2023]
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13
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Klement T, Milker S, Jäger G, Grande PM, Domínguez de María P, Büchs J. Biomass pretreatment affects Ustilago maydis in producing itaconic acid. Microb Cell Fact 2012; 11:43. [PMID: 22480369 PMCID: PMC3364905 DOI: 10.1186/1475-2859-11-43] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Accepted: 04/05/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the last years, the biotechnological production of platform chemicals for fuel components has become a major focus of interest. Although ligno-cellulosic material is considered as suitable feedstock, the almost inevitable pretreatment of this recalcitrant material may interfere with the subsequent fermentation steps. In this study, the fungus Ustilago maydis was used to produce itaconic acid as platform chemical for the synthesis of potential biofuels such as 3-methyltetrahydrofuran. No studies, however, have investigated how pretreatment of ligno-cellulosic biomass precisely influences the subsequent fermentation by U. maydis. Thus, this current study aims to first characterize U. maydis in shake flasks and then to evaluate the influence of three exemplary pretreatment methods on the cultivation and itaconic acid production of this fungus. Cellulose enzymatically hydrolysed in seawater and salt-assisted organic-acid catalysed cellulose were investigated as substrates. Lastly, hydrolysed hemicellulose from fractionated beech wood was applied as substrate. RESULTS U. maydis was characterized on shake flask level regarding its itaconic acid production on glucose. Nitrogen limitation was shown to be a crucial condition for the production of itaconic acid. For itaconic acid concentrations above 25 g/L, a significant product inhibition was observed. Performing experiments that simulated influences of possible pretreatment methods, U. maydis was only slightly affected by high osmolarities up to 3.5 osmol/L as well as of 0.1 M oxalic acid. The production of itaconic acid was achieved on pretreated cellulose in seawater and on the hydrolysed hemicellulosic fraction of pretreated beech wood. CONCLUSION The fungus U. maydis is a promising producer of itaconic acid, since it grows as single cells (yeast-like) in submerged cultivations and it is extremely robust in high osmotic media and real seawater. Moreover, U. maydis can grow on the hemicellulosic fraction of pretreated beech wood. Thereby, this fungus combines important advantages of yeasts and filamentous fungi. Nevertheless, the biomass pretreatment does indeed affect the subsequent itaconic acid production. Although U. maydis is insusceptible to most possible impurities from pretreatment, high amounts of salts or residues of organic acids can slow microbial growth and decrease the production. Consequently, the pretreatment step needs to fit the prerequisites defined by the actual microorganisms applied for fermentation.
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Affiliation(s)
- Tobias Klement
- AVT - Biochemical Engineering, RWTH Aachen University, Worringerweg 1, D-52074 Aachen, Germany
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Jäger G, Girfoglio M, Dollo F, Rinaldi R, Bongard H, Commandeur U, Fischer R, Spiess AC, Büchs J. How recombinant swollenin from Kluyveromyces lactis affects cellulosic substrates and accelerates their hydrolysis. BIOTECHNOLOGY FOR BIOFUELS 2011; 4:33. [PMID: 21943248 PMCID: PMC3203333 DOI: 10.1186/1754-6834-4-33] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 09/23/2011] [Indexed: 05/02/2023]
Abstract
BACKGROUND In order to generate biofuels, insoluble cellulosic substrates are pretreated and subsequently hydrolyzed with cellulases. One way to pretreat cellulose in a safe and environmentally friendly manner is to apply, under mild conditions, non-hydrolyzing proteins such as swollenin - naturally produced in low yields by the fungus Trichoderma reesei. To yield sufficient swollenin for industrial applications, the first aim of this study is to present a new way of producing recombinant swollenin. The main objective is to show how swollenin quantitatively affects relevant physical properties of cellulosic substrates and how it affects subsequent hydrolysis. RESULTS After expression in the yeast Kluyveromyces lactis, the resulting swollenin was purified. The adsorption parameters of the recombinant swollenin onto cellulose were quantified for the first time and were comparable to those of individual cellulases from T. reesei. Four different insoluble cellulosic substrates were then pretreated with swollenin. At first, it could be qualitatively shown by macroscopic evaluation and microscopy that swollenin caused deagglomeration of bigger cellulose agglomerates as well as dispersion of cellulose microfibrils (amorphogenesis). Afterwards, the effects of swollenin on cellulose particle size, maximum cellulase adsorption and cellulose crystallinity were quantified. The pretreatment with swollenin resulted in a significant decrease in particle size of the cellulosic substrates as well as in their crystallinity, thereby substantially increasing maximum cellulase adsorption onto these substrates. Subsequently, the pretreated cellulosic substrates were hydrolyzed with cellulases. Here, pretreatment of cellulosic substrates with swollenin, even in non-saturating concentrations, significantly accelerated the hydrolysis. By correlating particle size and crystallinity of the cellulosic substrates with initial hydrolysis rates, it could be shown that the swollenin-induced reduction in particle size and crystallinity resulted in high cellulose hydrolysis rates. CONCLUSIONS Recombinant swollenin can be easily produced with the robust yeast K. lactis. Moreover, swollenin induces deagglomeration of cellulose agglomerates as well as amorphogenesis (decrystallization). For the first time, this study quantifies and elucidates in detail how swollenin affects different cellulosic substrates and their hydrolysis.
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Affiliation(s)
- Gernot Jäger
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University,
Worringerweg 1, D-52074 Aachen, Germany
| | - Michele Girfoglio
- Institute of Molecular Biotechnology, RWTH Aachen University, Worringerweg 1,
D-52074 Aachen, Germany
| | - Florian Dollo
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University,
Worringerweg 1, D-52074 Aachen, Germany
| | - Roberto Rinaldi
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470
Mülheim an der Ruhr, Germany
| | - Hans Bongard
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470
Mülheim an der Ruhr, Germany
| | - Ulrich Commandeur
- Institute of Molecular Biotechnology, RWTH Aachen University, Worringerweg 1,
D-52074 Aachen, Germany
| | - Rainer Fischer
- Institute of Molecular Biotechnology, RWTH Aachen University, Worringerweg 1,
D-52074 Aachen, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME),
Forckenbeckstrasse 6, D-52074 Aachen, Germany
| | - Antje C Spiess
- AVT-Aachener Verfahrenstechnik, Enzyme Process Technology, RWTH Aachen University,
Worringerweg 1, D-52074 Aachen, Germany
| | - Jochen Büchs
- AVT-Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University,
Worringerweg 1, D-52074 Aachen, Germany
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