Dataset Information

Metabolic engineering reveals the relative importance of different sugar catabolic pathways during growth of Aspergillus niger on plant biomass

ABSTRACT: 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)

ORGANISM(S): Aspergillus niger

PROVIDER: GSE196397 | GEO | 2022/08/31

REPOSITORIES: GEO

ACCESS DATA

Similar Datasets

Project description:Enzymatic degradation of plant biomass requires the coordinated action of various enzymes. In this study, the production of reducing sugars from pectic substrates and sugar beet pulp (SBP) was investigated and compared using commercial enzyme preparations, including M2, pectinase (E1) from Aspergillus niger, Viscozyme® L (V-L) and L-40. V-L, a cellulolytic enzyme mix produced by Aspergillus sp. was further evaluated as the most robust enzyme cocktail with the strongest SBP degradation ability in terms of dynamic release of monosaccharides, methanol, and acetate from substrate SBP. Glucose, the building block of cellulose, was the first product to reach its maximum concentration within 2.5 hours. In contrast, the major monosaccharides in pectin, including arabinose and galacturonic acid, were continuously released from the residue until reaching a peak of 2,092 mg L-1 and 7,069 mg L-1 after 19 hours of fermentation. Label-free proteomics analysis (MS/MS) of V-L revealed 151 individual proteins. Of these, 137 proteins were annotated as containing a carbohydrate-active enzymes (CAZyme) module. Notably, of the 50 most abundant proteins, which accounted for over 90% of the protein amount in V-L, ca. 40% were predicted to be involved in pectin degradation (belonging mainly to CAZyme families GH28, CE8, CE16, PL1 and PL3). To reveal the role of individual putative key enzymes of pectic substrate decomposition, two galacturonases (PglA and PglB), which are core of pectin-degrading enzymes of the GH28 family, were heterologously expressed in Pichia pastoris strain GB10 and further characterized. PglA and PglB demonstrated maximum activity at 57 °C and 67 °C, respectively. Both enzymes exhibited endo-cleavage patterns towards polygalacturonic acid (PGA) and released oligosaccharides with different degrees of polymerization (DP). In conclusion, our study identified two pectin-cleaving enzymes present in major amounts in a highly efficient SBP-saccharifying enzyme mix and characterized some of their properties. Further studies along this line may facilitate the understanding of SBP degradation and may help to design improved artificial enzyme mixtures with a lower complexity than V-L for future application in biotechnology.

Dataset Information

Metabolic engineering reveals the relative importance of different sugar catabolic pathways during growth of Aspergillus niger on plant biomass

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure