CAZymes from the thermophilic fungus Thermoascus aurantiacus are induced by C5 and C6 sugars

  • 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.
Author:Raphael Gabriel, Rebecca Müller, Lena Floerl, Cynthia Hopson, Simon HarthGND, Timo Schürg, Andre Fleissner, Steven W. Singer
Parent Title (English):Biotechnology for biofuels
Publisher:BioMed Central
Place of publication:London
Document Type:Article
Date of Publication (online):2021/08/12
Date of first Publication:2021/08/12
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/04/19
Tag:CAZy; Cellulase gene expression; Filamentous fungi; Thermoascus aurantiacus; Transcriptomics
Issue:art. 169
Page Number:13
First Page:1
Last Page:13
The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated in a credit line to the data.
This work was supported by the German Academic Exchange Service (DAAD) through a granted stipend to R.G. (Jahresstipendien für Doktorandinnen und Doktoranden, Studienjahr 2018/19 under the Program Number 57380837). Additional funding for student internships was provided by the Austrian Marshall Plan Foundation (L.F., R.G.). Portions of this work were funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Bioenergy Technologies Office. Portions of this work were performed at the DOE Joint BioEnergy Institute ( supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, through contract DE‑AC02‑05CH11231 between Lawrence Berkeley National Laboratory and the U.S. Department of Energy. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Licence (German):License LogoCreative Commons - Namensnennung 4.0