GSE196397
Metabolic engineering reveals the relative importance of different sugar catabolic pathways during growth of Aspergillus niger on plant biomass
To evaluate the relative contribution of individual sugar catabolic pathways to the overall physiology of A. niger during growth on plant biomass, the A. niger sugar catabolic pathways involved in converting the most common monomers of plant biomass polysaccharides were blocked, and the phenotype as well as the transcriptomic response of these single-pathway deletion mutants was analysed on two distinct plant biomass substrates: wheat bran (WB) and sugar beet pulp (SBP). Deletion of all the above catabolic pathways were also combined in a single strain (?all), to evaluate whether other compounds of plant biomass could still support growth of A. niger when utilization of the major sugar components is blocked. On both WB and SBP, the strongest affected single-pathway deletion mutants were the PCP and glycolysis deficient mutants, delta-xkiA and delta-hxkA/delta-glkA, respectively. Especially on WB, which is a particularly rich substrate in pentose sugars, blocking PCP caused a significant effect in delta-xkiA with respect to both growth and transcriptomic response. However, delta-hxkA/delta-glkA was shown to be the most critically affected strain. On both substrates, combined deletion of hxkA and glkA resulted in the strongest growth reduction of all the single-pathway mutants, very similar to the multi-pathway deletion mutant delta-all. This result clearly pointed to glycolysis as the most essential and indispensable pathway for the survival of A. niger on these substrates. Since cellulose is not a preferred carbon source for A. niger, it seems that the double deletion of hxkA and glkA mostly affected the utilization of starch. (Note: A portion of this research was performed on a project award (10.46936/expl.proj.2019.51072/60006675) from the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility sponsored by the Biological and Environmental Research program under Contract No. DE-AC05-76RL01830) Overall design: mRNA profiling of five Aspergillus niger strains grown on wheat bran or sugar beet pulp at two time points.