Unraveling the regulation of sugar beet pulp utilization in the industrially relevant fungus Aspergillus niger

Sandra Garrigues; Roland S Kun; Mao Peng; Diane Bauer; Keykhosrow Keymanesh; Anna Lipzen; Vivian Ng; Igor V Grigoriev; Ronald P de Vries

doi:10.1016/j.isci.2022.104065

Unraveling the regulation of sugar beet pulp utilization in the industrially relevant fungus Aspergillus niger

iScience. 2022 Mar 12;25(4):104065. doi: 10.1016/j.isci.2022.104065. eCollection 2022 Apr 15.

Authors

Sandra Garrigues¹, Roland S Kun¹, Mao Peng¹, Diane Bauer², Keykhosrow Keymanesh², Anna Lipzen², Vivian Ng², Igor V Grigoriev², Ronald P de Vries¹

Affiliations

¹ Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT Utrecht, the Netherlands.
² USA Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA.

Abstract

Efficient utilization of agro-industrial waste, such as sugar beet pulp, is crucial for the bio-based economy. The fungus Aspergillus niger possesses a wide array of enzymes that degrade complex plant biomass substrates, and several regulators have been reported to play a role in their production. The role of the regulators GaaR, AraR, and RhaR in sugar beet pectin degradation has previously been reported. However, genetic regulation of the degradation of sugar beet pulp has not been assessed in detail. In this study, we generated a set of single and combinatorial deletion mutants targeting the pectinolytic regulators GaaR, AraR, RhaR, and GalX as well as the (hemi-)cellulolytic regulators XlnR and ClrB to address their relative contribution to the utilization of sugar beet pulp. We show that A. niger has a flexible regulatory network, adapting to the utilization of (hemi-)cellulose at early timepoints when pectin degradation is impaired.

Keywords: Microbial metabolism; Mycology.