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Kun RS, Garrigues S, Di Falco M, Tsang A, de Vries RP. The chimeric GaaR-XlnR transcription factor induces pectinolytic activities in the presence of D-xylose in Aspergillus niger. Appl Microbiol Biotechnol 2021; 105:5553-5564. [PMID: 34236481 PMCID: PMC8285313 DOI: 10.1007/s00253-021-11428-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 06/10/2021] [Accepted: 06/12/2021] [Indexed: 01/03/2023]
Abstract
Abstract Aspergillus niger is a filamentous fungus well known for its ability to produce a wide variety of pectinolytic enzymes, which have many applications in the industry. The transcriptional activator GaaR is induced by 2-keto-3-deoxy-L-galactonate, a compound derived from D-galacturonic acid, and plays a major role in the regulation of pectinolytic genes. The requirement for inducer molecules can be a limiting factor for the production of enzymes. Therefore, the generation of chimeric transcription factors able to activate the expression of pectinolytic genes by using underutilized agricultural residues would be highly valuable for industrial applications. In this study, we used the CRISPR/Cas9 system to generate three chimeric GaaR-XlnR transcription factors expressed by the xlnR promoter by swapping the N-terminal region of the xylanolytic regulator XlnR to that of the GaaR in A. niger. As a test case, we constructed a PpgaX-hph reporter strain to evaluate the alteration of transcription factor specificity in the chimeric mutants. Our results showed that the chimeric GaaR-XlnR transcription factor was induced in the presence of D-xylose. Additionally, we generated a constitutively active GaaR-XlnR V756F version of the most efficient chimeric transcription factor to better assess its activity. Proteomics analysis confirmed the production of several pectinolytic enzymes by ΔgaaR mutants carrying the chimeric transcription factor. This correlates with the improved release of D-galacturonic acid from pectin by the GaaR-XlnR V756F mutant, as well as by the increased L-arabinose release from the pectin side chains by both chimeric mutants under inducing condition, which is required for efficient degradation of pectin. Key points • Chimeric transcription factors were generated by on-site mutations using CRISPR/Cas9. • PpgaX-hph reporter strain allowed for the screening of functional GaaR-XlnR mutants. • Chimeric GaaR-XlnR induced pectinolytic activities in the presence of D-xylose. Supplementary Information The online version contains supplementary material available at 10.1007/s00253-021-11428-2.
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Affiliation(s)
- Roland S Kun
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584, CT, Utrecht, The Netherlands
| | - Sandra Garrigues
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584, CT, Utrecht, The Netherlands
| | - Marcos Di Falco
- Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada
| | - Adrian Tsang
- Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke Street West, Montreal, Quebec, H4B 1R6, Canada
| | - Ronald P de Vries
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584, CT, Utrecht, The Netherlands.
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Kun RS, Garrigues S, Di Falco M, Tsang A, de Vries RP. Blocking utilization of major plant biomass polysaccharides leads Aspergillus niger towards utilization of minor components. Microb Biotechnol 2021; 14:1683-1698. [PMID: 34114741 PMCID: PMC8313289 DOI: 10.1111/1751-7915.13835] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/08/2021] [Accepted: 05/10/2021] [Indexed: 11/28/2022] Open
Abstract
Fungi produce a wide range of enzymes that allow them to grow on diverse plant biomass. Wheat bran is a low-cost substrate with high potential for biotechnological applications. It mainly contains cellulose and (arabino)xylan, as well as starch, proteins, lipids and lignin to a lesser extent. In this study, we dissected the regulatory network governing wheat bran degradation in Aspergillus niger to assess the relative contribution of the regulators to the utilization of this plant biomass substrate. Deletion of genes encoding transcription factors involved in (hemi-)cellulose utilization (XlnR, AraR, ClrA and ClrB) individually and in combination significantly reduced production of polysaccharide-degrading enzymes, but retained substantial growth on wheat bran. Proteomic analysis suggested the ability of A. niger to grow on other carbon components, such as starch, which was confirmed by the additional deletion of the amylolytic regulator AmyR. Growth was further reduced but not impaired, indicating that other minor components provide sufficient energy for residual growth, displaying the flexibility of A. niger, and likely other fungi, in carbon utilization. Better understanding of the complexity and flexibility of fungal regulatory networks will facilitate the generation of more efficient fungal cell factories that use plant biomass as a substrate.
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Affiliation(s)
- Roland S. Kun
- Fungal PhysiologyWesterdijk Fungal Biodiversity Institute & Fungal Molecular PhysiologyUtrecht UniversityUppsalalaan 8Utrecht3584 CTThe Netherlands
| | - Sandra Garrigues
- Fungal PhysiologyWesterdijk Fungal Biodiversity Institute & Fungal Molecular PhysiologyUtrecht UniversityUppsalalaan 8Utrecht3584 CTThe Netherlands
| | - Marcos Di Falco
- Centre for Structural and Functional GenomicsConcordia University7141 Sherbrooke Street WestMontrealQCH4B 1R6Canada
| | - Adrian Tsang
- Centre for Structural and Functional GenomicsConcordia University7141 Sherbrooke Street WestMontrealQCH4B 1R6Canada
| | - Ronald P. de Vries
- Fungal PhysiologyWesterdijk Fungal Biodiversity Institute & Fungal Molecular PhysiologyUtrecht UniversityUppsalalaan 8Utrecht3584 CTThe Netherlands
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From lignocellulose to plastics: Knowledge transfer on the degradation approaches by fungi. Biotechnol Adv 2021; 50:107770. [PMID: 33989704 DOI: 10.1016/j.biotechadv.2021.107770] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 05/04/2021] [Accepted: 05/08/2021] [Indexed: 01/21/2023]
Abstract
In this review, we argue that there is much to be learned by transferring knowledge from research on lignocellulose degradation to that on plastic. Plastic waste accumulates in the environment to hazardous levels, because it is inherently recalcitrant to biological degradation. Plants evolved lignocellulose to be resistant to degradation, but with time, fungi became capable of utilising it for their nutrition. Examples of how fungal strategies to degrade lignocellulose could be insightful for plastic degradation include how fungi overcome the hydrophobicity of lignin (e.g. production of hydrophobins) and crystallinity of cellulose (e.g. oxidative approaches). In parallel, knowledge of the methods for understanding lignocellulose degradation could be insightful such as advanced microscopy, genomic and post-genomic approaches (e.g. gene expression analysis). The known limitations of biological lignocellulose degradation, such as the necessity for physiochemical pretreatments for biofuel production, can be predictive of potential restrictions of biological plastic degradation. Taking lessons from lignocellulose degradation for plastic degradation is also important for biosafety as engineered plastic-degrading fungi could also have increased plant biomass degrading capabilities. Even though plastics are significantly different from lignocellulose because they lack hydrolysable C-C or C-O bonds and therefore have higher recalcitrance, there are apparent similarities, e.g. both types of compounds are mixtures of hydrophobic polymers with amorphous and crystalline regions, and both require hydrolases and oxidoreductases for their degradation. Thus, many lessons could be learned from fungal lignocellulose degradation.
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Khosravi C, Kowalczyk JE, Chroumpi T, Battaglia E, Aguilar Pontes MV, Peng M, Wiebenga A, Ng V, Lipzen A, He G, Bauer D, Grigoriev IV, de Vries RP. Transcriptome analysis of Aspergillus niger xlnR and xkiA mutants grown on corn Stover and soybean hulls reveals a highly complex regulatory network. BMC Genomics 2019; 20:853. [PMID: 31726994 PMCID: PMC6854810 DOI: 10.1186/s12864-019-6235-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 10/28/2019] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Enzymatic plant biomass degradation by fungi is a highly complex process and one of the leading challenges in developing a biobased economy. Some industrial fungi (e.g. Aspergillus niger) have a long history of use with respect to plant biomass degradation and for that reason have become 'model' species for this topic. A. niger is a major industrial enzyme producer that has a broad ability to degrade plant based polysaccharides. A. niger wild-type, the (hemi-)cellulolytic regulator (xlnR) and xylulokinase (xkiA1) mutant strains were grown on a monocot (corn stover, CS) and dicot (soybean hulls, SBH) substrate. The xkiA1 mutant is unable to utilize the pentoses D-xylose and L-arabinose and the polysaccharide xylan, and was previously shown to accumulate inducers for the (hemi-)cellulolytic transcriptional activator XlnR and the arabinanolytic transcriptional activator AraR in the presence of pentoses, resulting in overexpression of their target genes. The xlnR mutant has reduced growth on xylan and down-regulation of its target genes. The mutants therefore have a similar phenotype on xylan, but an opposite transcriptional effect. D-xylose and L-arabinose are the most abundant monosaccharides after D-glucose in nearly all plant-derived biomass materials. In this study we evaluated the effect of the xlnR and xkiA1 mutation during growth on two pentose-rich substrates by transcriptome analysis. RESULTS Particular attention was given to CAZymes, metabolic pathways and transcription factors related to the plant biomass degradation. Genes coding for the main enzymes involved in plant biomass degradation were down-regulated at the beginning of the growth on CS and SBH. However, at a later time point, significant differences were found in the expression profiles of both mutants on CS compared to SBH. CONCLUSION This study demonstrates the high complexity of the plant biomass degradation process by fungi, by showing that mutant strains with fairly straightforward phenotypes on pure mono- and polysaccharides, have much less clear-cut phenotypes and transcriptomes on crude plant biomass.
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Affiliation(s)
- Claire Khosravi
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, the Netherlands
| | - Joanna E. Kowalczyk
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, the Netherlands
| | - Tania Chroumpi
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, the Netherlands
| | - Evy Battaglia
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, the Netherlands
| | - Maria-Victoria Aguilar Pontes
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, the Netherlands
| | - Mao Peng
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, the Netherlands
| | - Ad Wiebenga
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, the Netherlands
| | - Vivian Ng
- US Department of Energy Joint Genome Institute, Walnut Creek, CA USA
| | - Anna Lipzen
- US Department of Energy Joint Genome Institute, Walnut Creek, CA USA
| | - Guifen He
- US Department of Energy Joint Genome Institute, Walnut Creek, CA USA
| | - Diane Bauer
- US Department of Energy Joint Genome Institute, Walnut Creek, CA USA
| | - Igor V. Grigoriev
- US Department of Energy Joint Genome Institute, Walnut Creek, CA USA
- Department of Plant and Microbial Biology, University of California, Berkeley, CA USA
| | - Ronald P. de Vries
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, the Netherlands
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Daly P, López SC, Peng M, Lancefield CS, Purvine SO, Kim Y, Zink EM, Dohnalkova A, Singan VR, Lipzen A, Dilworth D, Wang M, Ng V, Robinson E, Orr G, Baker SE, Bruijnincx PCA, Hildén KS, Grigoriev IV, Mäkelä MR, de Vries RP. Dichomitus squalens
partially tailors its molecular responses to the composition of solid wood. Environ Microbiol 2018; 20:4141-4156. [DOI: 10.1111/1462-2920.14416] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 09/11/2018] [Accepted: 09/13/2018] [Indexed: 12/23/2022]
Affiliation(s)
- Paul Daly
- Fungal Physiology Westerdijk Fungal Biodiversity Institute and Fungal Molecular Physiology, Utrecht University Utrecht The Netherlands
| | - Sara Casado López
- Fungal Physiology Westerdijk Fungal Biodiversity Institute and Fungal Molecular Physiology, Utrecht University Utrecht The Netherlands
| | - Mao Peng
- Fungal Physiology Westerdijk Fungal Biodiversity Institute and Fungal Molecular Physiology, Utrecht University Utrecht The Netherlands
| | - Christopher S. Lancefield
- Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science Utrecht University Utrecht The Netherlands
| | - Samuel O. Purvine
- Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA USA
| | - Young‐Mo Kim
- Biological Sciences Division Pacific Northwest National Laboratory Richland WA USA
| | - Erika M. Zink
- Biological Sciences Division Pacific Northwest National Laboratory Richland WA USA
| | - Alice Dohnalkova
- Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA USA
| | | | - Anna Lipzen
- US Department of Energy Joint Genome Institute Walnut Creek CA USA
| | - David Dilworth
- US Department of Energy Joint Genome Institute Walnut Creek CA USA
| | - Mei Wang
- US Department of Energy Joint Genome Institute Walnut Creek CA USA
| | - Vivian Ng
- US Department of Energy Joint Genome Institute Walnut Creek CA USA
| | - Errol Robinson
- Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA USA
| | - Galya Orr
- Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA USA
| | - Scott E. Baker
- Environmental Molecular Sciences Laboratory Pacific Northwest National Laboratory Richland WA USA
| | - Pieter C. A. Bruijnincx
- Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science Utrecht University Utrecht The Netherlands
| | | | | | - Miia R. Mäkelä
- Department of Microbiology University of Helsinki Helsinki Finland
| | - Ronald P. de Vries
- Fungal Physiology Westerdijk Fungal Biodiversity Institute and Fungal Molecular Physiology, Utrecht University Utrecht The Netherlands
- Department of Microbiology University of Helsinki Helsinki Finland
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