Uncovering the genome-wide transcriptional responses of the filamentous fungus Aspergillus niger to lignocellulose using RNA sequencing

Delmas, St�phane; Pullan, Steven T.; Gaddipati, Sanyasi; Kokolski, Matthew; Malla, Sunir; Blythe, Martin J.; Ibbett, Roger; Campbell, Maria; Liddell, Susan; Aboobaker, Aziz; Tucker, Gregory A.; Archer, David B.

Abstract

A key challenge in the production of second generation biofuels is the conversion of lignocellulosic substrates into fermentable sugars. Enzymes, particularly those from fungi, are a central part of this process, and many have been isolated and characterised. However, relatively little is known of how fungi respond to lignocellulose and produce the enzymes necessary for dis-assembly of plant biomass. We studied the physiological response of the fungus Aspergillus niger when exposed to wheat straw as a model lignocellulosic substrate. Using RNA sequencing we showed that, 24 hours after exposure to straw, gene expression of known and presumptive plant cell wall–degrading enzymes represents a huge investment for the cells (about 20% of the total mRNA). Our results also uncovered new esterases and surface interacting proteins that might form part of the fungal arsenal of enzymes for the degradation of plant biomass. Using transcription factor deletion mutants (xlnR and creA) to study the response to both lignocellulosic substrates and low carbon source concentrations, we showed that a subset of genes coding for degradative enzymes is induced by starvation. Our data support a model whereby this subset of enzymes plays a scouting role under starvation conditions, testing for available complex polysaccharides and liberating inducing sugars, that triggers the subsequent induction of the majority of hydrolases. We also showed that antisense transcripts are abundant and that their expression can be regulated by growth conditions.

Citation

Delmas, S., Pullan, S. T., Gaddipati, S., Kokolski, M., Malla, S., Blythe, M. J., Ibbett, R., Campbell, M., Liddell, S., Aboobaker, A., Tucker, G. A., & Archer, D. B. (2012). Uncovering the genome-wide transcriptional responses of the filamentous fungus Aspergillus niger to lignocellulose using RNA sequencing. PLoS Genetics, 8(8), Article e1002875. https://doi.org/10.1371/journal.pgen.1002875

• Journal Article Type: Article
• Publication Date: Aug 9, 2012
• Deposit Date: Apr 15, 2014
• Publicly Available Date: Apr 15, 2014
• Journal: PLoS Genetics
• Print ISSN: 1553-7390
• Electronic ISSN: 1553-7404
• Publisher: Public Library of Science
• Peer Reviewed: Peer Reviewed
• Volume: 8
• Issue: 8
• Article Number: e1002875
• DOI: https://doi.org/10.1371/journal.pgen.1002875
• Public URL: https://nottingham-repository.worktribe.com/output/711001
• Publisher URL: http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002875