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Gabriel R, Mueller R, Floerl L, Hopson C, Harth S, Schuerg T, Fleissner A, Singer SW. CAZymes from the thermophilic fungus Thermoascus aurantiacus are induced by C5 and C6 sugars. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:169. [PMID: 34384463 PMCID: PMC8359064 DOI: 10.1186/s13068-021-02018-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Filamentous fungi are excellent lignocellulose degraders, which they achieve through producing carbohydrate active enzymes (CAZymes). CAZyme production is highly orchestrated and gene expression analysis has greatly expanded understanding of this important biotechnological process. The thermophilic fungus Thermoascus aurantiacus secretes highly active thermostable enzymes that enable saccharifications at higher temperatures; however, the genome-wide measurements of gene expression in response to CAZyme induction are not understood. RESULTS A fed-batch system with plant biomass-derived sugars D-xylose, L-arabinose and cellobiose established that these sugars induce CAZyme expression in T. aurantiacus. The C5 sugars induced both cellulases and hemicellulases, while cellobiose specifically induced cellulases. A minimal medium formulation was developed to enable gene expression studies of T. aurantiacus with these inducers. It was found that d-xylose and L-arabinose strongly induced a wide variety of CAZymes, auxiliary activity (AA) enzymes and carbohydrate esterases (CEs), while cellobiose facilitated lower expression of mostly cellulase genes. Furthermore, putative orthologues of different unfolded protein response genes were up-regulated during the C5 sugar feeding together with genes in the C5 sugar assimilation pathways. CONCLUSION This work has identified two additional CAZyme inducers for T. aurantiacus, L-arabinose and cellobiose, along with D-xylose. A combination of biochemical assays and RNA-seq measurements established that C5 sugars induce a suite of cellulases and hemicellulases, providing paths to produce broad spectrum thermotolerant enzymatic mixtures.
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Affiliation(s)
- Raphael Gabriel
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 9720, USA
- Joint BioEnergy Institute, Emeryville, CA, 94608, USA
- Institut Für Genetik, Technische Universität Braunschweig, Spielmannstr. 7, 38106, Braunschweig, Germany
| | - Rebecca Mueller
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 9720, USA
- Joint BioEnergy Institute, Emeryville, CA, 94608, USA
- Institut Für Genetik, Technische Universität Braunschweig, Spielmannstr. 7, 38106, Braunschweig, Germany
| | - Lena Floerl
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 9720, USA
- Joint BioEnergy Institute, Emeryville, CA, 94608, USA
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences Vienna (BOKU), Muthgasse 18, 1190, Vienna, Austria
- Laboratory of Food Systems Biotechnology, Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Cynthia Hopson
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 9720, USA
- Joint BioEnergy Institute, Emeryville, CA, 94608, USA
- Department of Chemical Engineering and Materials, Faculty of Chemistry, Complutense University of Madrid, Av. Complutense s/n, 28040, Madrid, Spain
| | - Simon Harth
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 9720, USA
- Joint BioEnergy Institute, Emeryville, CA, 94608, USA
- Frankfurt Institute of Molecular Biosciences, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Timo Schuerg
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 9720, USA
- Joint BioEnergy Institute, Emeryville, CA, 94608, USA
| | - Andre Fleissner
- Institut Für Genetik, Technische Universität Braunschweig, Spielmannstr. 7, 38106, Braunschweig, Germany
- Braunschweig Integrated Centre of Systems Biology (BRICS), Rebenring 56, 38106, Braunschweig, Germany
| | - Steven W Singer
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 9720, USA.
- Joint BioEnergy Institute, Emeryville, CA, 94608, USA.
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Badieyan S, Bevan DR, Zhang C. Study and design of stability in GH5 cellulases. Biotechnol Bioeng 2011; 109:31-44. [PMID: 21809329 DOI: 10.1002/bit.23280] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 06/30/2011] [Accepted: 07/11/2011] [Indexed: 11/07/2022]
Abstract
Thermostable enzymes that hydrolyze lignocellulosic materials provide potential advantages in process configuration and enhancement of production efficiency over their mesophilic counterparts in the bioethanol industry. In this study, the dynamics of β-1,4-endoglucanases (EC: 3.2.1.4) from family 5 of glycoside hydrolases (GH5) were investigated computationally. The conformational flexibility of 12 GH5 cellulases, ranging from psychrophilic to hyperthermophilic, was investigated by molecular dynamics (MD) simulations at elevated temperatures. The results indicated that the protein flexibility and optimum activity temperatures are appreciably correlated. Intra-protein interactions, packing density and solvent accessible area were further examined in crystal structures to investigate factors that are possibly involved in higher rigidity of thermostable cellulases. The MD simulations and the rules learned from analyses of stabilizing factors were used in design of mutations toward the thermostabilization of cellulase C, one of the GH5 endoglucanases. This enzyme was successfully stabilized both chemically and thermally by introduction of a new disulfide cross-link to its highly mobile 56-amino acid subdomain.
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Affiliation(s)
- Somayesadat Badieyan
- Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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Viikari L, Alapuranen M, Puranen T, Vehmaanperä J, Siika-Aho M. Thermostable enzymes in lignocellulose hydrolysis. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2007; 108:121-45. [PMID: 17589813 DOI: 10.1007/10_2007_065] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Thermostable enzymes offer potential benefits in the hydrolysis of lignocellulosic substrates; higher specific activity decreasing the amount of enzymes, enhanced stability allowing improved hydrolysis performance and increased flexibility with respect to process configurations, all leading to improvement of the overall economy of the process. New thermostable cellulase mixtures were composed of cloned fungal enzymes for hydrolysis experiments. Three thermostable cellulases, identified as the most promising enzymes in their categories (cellobiohydrolase, endoglucanase and beta-glucosidase), were cloned and produced in Trichoderma reesei and mixed to compose a novel mixture of thermostable cellulases. Thermostable xylanase was added to enzyme preparations used on substrates containing residual hemicellulose. The new optimised thermostable enzyme mixtures were evaluated in high temperature hydrolysis experiments on technical steam pretreated raw materials: spruce and corn stover. The hydrolysis temperature could be increased by about 10-15 degrees C, as compared with present commercial Trichoderma enzymes. The same degree of hydrolysis, about 90% of theoretical, measured as individual sugars, could be obtained with the thermostable enzymes at 60 degrees C as with the commercial enzymes at 45 degrees C. Clearly more efficient hydrolysis per assayed FPU unit or per amount of cellobiohydrolase I protein used was obtained. The maximum FPU activity of the novel enzyme mixture was about 25% higher at the optimum temperature at 65 degrees C, as compared with the highest activity of the commercial reference enzyme at 60 degrees C. The results provide a promising basis to produce and formulate improved enzyme products. These products can have high temperature stability in process conditions in the range of 55-60 degrees C (with present industrial products at 45-50 degrees C) and clearly improved specific activity, essentially decreasing the protein dosage required for an efficient hydrolysis of lignocellulosic substrates. New types of process configurations based on thermostable enzymes are discussed.
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Affiliation(s)
- Liisa Viikari
- University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland.
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Walsh G, Murphy RA, Killeen GF, Power RF. Quantification of supplemental enzymes in animal feedingstuffs by radial enzyme diffusion. Appl Microbiol Biotechnol 2004; 67:70-4. [PMID: 15580494 DOI: 10.1007/s00253-004-1826-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Revised: 10/22/2004] [Accepted: 10/23/2004] [Indexed: 11/29/2022]
Abstract
Methods are described which facilitate quantification of supplemental cellulase, protease and alpha-amylase when added to animal feedingstuffs at normal industrial inclusion levels. The methods entail extraction of the enzymes from the feedingstuffs by agitation in buffer followed by quantification of extract activity using radial diffusion techniques. A linear relationship between the diameter of the zone of hydrolyzed substrate and the log of the enzyme activity applied is observed over a broad activity range. Assay of a feedingstuff supplemented with 1 kg t(-1) cellulase, protease and alpha-amylase yielded net supplemental activity recoveries of 104+/-11.7%, 91.3+/-6.74% and 126+/-29.5%, respectively. A similar assay method did not prove sufficiently sensitive to facilitate detection of xylanase at typical in-feed inclusion levels. The levels of endogenous cellulase, protease and alpha-amylase activity detected in the unsupplemented feedingstuffs were equivalent to 6.4+/-0.47%, 6.6+/-0.82% and 29.0+/-14.1%, respectively, of a 1 kg t(-1) supplement. The methods are technically straightforward and will facilitate determination of enzyme stabilities during processes such as high-temperature pelleting of feedingstuffs, as well as allowing more rigorous quality control related to enzyme-supplemented animal feedingstuffs.
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Affiliation(s)
- G Walsh
- Department of Chemical and Environmental Science, University of Limerick, Limerick, Ireland.
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Lo Leggio L, Larsen S. The 1.62 A structure of Thermoascus aurantiacus endoglucanase: completing the structural picture of subfamilies in glycoside hydrolase family 5. FEBS Lett 2002; 523:103-8. [PMID: 12123813 DOI: 10.1016/s0014-5793(02)02954-x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The crystal structure of Thermoascus aurantiacus endoglucanase (Cel5A), a family 5 glycoside hydrolase, has been determined to 1.62 A resolution by multiple isomorphous replacement with anomalous scattering. It is the first report of a structure in the subfamily to which Cel5A belongs. Cel5A consists solely of a catalytic module with compact eight-fold beta/alpha barrel architecture. The length of the tryptophan-rich substrate binding groove suggests the presence of substrate binding subsites -4 to +3. Structural comparison shows that two glycines are completely conserved in the family, in addition to the two catalytic glutamates and six other conserved residues previously identified. Gly 44 in particular is part of a type IV C-terminal helix capping motif, whose disruption is likely to affect the position of an essential conserved arginine. One aromatic residue (Trp 170 in Cel5A), not conserved in term of sequence, is nonetheless spatially conserved in the substrate binding groove. Its role might be to force the bend that occurs in the polysaccharide chain on binding, thus favoring substrate distortion at subsite -1.
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Affiliation(s)
- Leila Lo Leggio
- Centre for Crystallographic Studies, Department of Chemistry, Chemical Institute, University of Copenhagen, Universitetsparken 5, DK-2100, Copenhagen, Denmark.
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Singh A, Goel R, Johri BN. Production of cellulolytic enzymes by immobilized Sporotrichum thermophile. Enzyme Microb Technol 1990; 12:464-8. [PMID: 1366631 DOI: 10.1016/0141-0229(90)90059-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Spores of Sporotrichum thermophile were immobilized in agar, polyacrylamide, and sodium alginate to generate in situ mycelium for production of cellulolytic enzymes. Immobilized mycelium was considerably less effective than free cells for cellulase productivity. Of the three gel types, agar beads proved to be the best carrier for the immobilized spores and subsequently generated mycelium. Results of repeated batch experiments suggested that the immobilized mycelia could be reused but at much reduced efficiency.
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Affiliation(s)
- A Singh
- Department of Microbiology, C.B.S.H., G.B.Pant University of Agriculture & Technology, Pantnagar, India
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