AUTHOR=Chroumpi Tania , Peng Mao , Markillie Lye Meng , Mitchell Hugh D. , Nicora Carrie D. , Hutchinson Chelsea M. , Paurus Vanessa , Tolic Nikola , Clendinen Chaevien S. , Orr Galya , Baker Scott E. , Mäkelä Miia R. , de Vries Ronald P. 

TITLE=Re-routing of Sugar Catabolism Provides a Better Insight Into Fungal Flexibility in Using Plant Biomass-Derived Monomers as Substrates

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2021.644216

DOI=10.3389/fbioe.2021.644216

ISSN=2296-4185

ABSTRACT=<p>The filamentous ascomycete <italic>Aspergillus niger</italic> has received increasing interest as a cell factory, being able to efficiently degrade plant cell wall polysaccharides as well as having an extensive metabolism to convert the released monosaccharides into value added compounds. The pentoses <sc>D</sc>-xylose and <sc>L</sc>-arabinose are the most abundant monosaccharides in plant biomass after the hexose <sc>D</sc>-glucose, being major constituents of xylan, pectin and xyloglucan. In this study, the influence of selected pentose catabolic pathway (PCP) deletion strains on growth on plant biomass and re-routing of sugar catabolism was addressed to gain a better understanding of the flexibility of this fungus in using plant biomass-derived monomers. The transcriptome, metabolome and proteome response of three PCP mutant strains, Δ<italic>larA</italic>Δ<italic>xyrA</italic>Δ<italic>xyrB</italic>, Δ<italic>ladA</italic>Δ<italic>xdhA</italic>Δ<italic>sdhA</italic> and Δ<italic>xkiA</italic>, grown on wheat bran (WB) and sugar beet pulp (SBP), was evaluated. Our results showed that despite the absolute impact of these PCP mutations on pure pentose sugars, they are not as critical for growth of <italic>A. niger</italic> on more complex biomass substrates, such as WB and SBP. However, significant phenotypic variation was observed between the two biomass substrates, but also between the different PCP mutants. This shows that the high sugar heterogeneity of these substrates in combination with the high complexity and adaptability of the fungal sugar metabolism allow for activation of alternative strategies to support growth.</p>