Blocking hexose entry into glycolysis activates alternative metabolic conversion of these sugars and upregulates pentose metabolism in Aspergillus nidulans

Abstract

BackgroundPlant biomass is the most abundant carbon source for many fungal species. In the biobased industry fungi, are used to produce lignocellulolytic enzymes to degrade agricultural waste biomass. Here we evaluated if it would be possible to create an Aspergillus nidulans strain that releases, but does not metabolize hexoses from plant biomass. For this purpose, metabolic mutants were generated that were impaired in glycolysis, by using hexokinase (hxkA) and glucokinase (glkA) negative strains. To prevent repression of enzyme production due to the hexose accumulation, strains were generated that combined these mutations with a deletion in creA, the repressor involved in regulating preferential use of different carbon catabolic pathways.ResultsPhenotypic analysis revealed reduced growth for the hxkA1 glkA4 mutant on wheat bran. However, hexoses did not accumulate during growth of the mutants on wheat bran, suggesting that glucose metabolism is re-routed towards alternative carbon catabolic pathways. The creAΔ4 mutation in combination with preventing initial phosphorylation in glycolysis resulted in better growth than the hxkA/glkA mutant and an increased expression of pentose catabolic and pentose phosphate pathway genes. This indicates that the reduced ability to use hexoses as carbon sources created a shift towards the pentose fraction of wheat bran as a major carbon source to support growth.ConclusionBlocking the direct entry of hexoses to glycolysis activates alternative metabolic conversion of these sugars in A. nidulans during growth on plant biomass, but also upregulates conversion of other sugars, such as pentoses.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-4609-x) contains supplementary material, which is available to authorized users.

Myceliophthora thermophila Xyr1 is predominantly involved in xylan degradation and xylose catabolism

“…First, we studied the transcript levels of the CAZy genes that contain at least one predicted auxiliary activity (AA), carbohydrate esterase (CE), glycoside hydrolase (GH) or polysaccharide lyase (PL) domain (Additional file 2). A selection was made of the CAZy families that are known or predicted to be involved in plant polysaccharide degradation in Aspergillus nidulans [32]. A cutoff fold change of the data from the mutant compared to the wild type of > 2.0 and a p value of ≤ 0.01 was used to identify differentially expressed genes (Fig.…”

Colonies of the fungus Aspergillus niger are highly differentiated to adapt to local carbon source variation

“…The aqueous phase, containing the polar metabolites, obtained from the chloroform:methanol extractions was processed for using GC-MS-based metabolomics data generation and analysis using pipelines described previously (Daly et al, 2018;Khosravi et al, 2018). Meta-boAnalyst (Xia et al, 2015) was used for the principal component analysis of the metabolite abundances.…”

Manganese Deficiency Is Required for High Itaconic Acid Production From D-Xylose in Aspergillus terreus

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