Aspergillus species are potent producers of enzymes involved in plant polysaccharide degradation. In nature, Aspergillus degrades the polysaccharides to monomeric sugars that can serve as a carbon source. Therefore, Aspergillus uses a variety of catabolic pathways to efficiently convert all the monomeric components of plant biomass. L-rhamnose catabolism in fungi has been described for the yeasts Pichia sptipitis and Debaryomyces hansenii (Watanabe et al., 2008). In Aspergillus niger this pathway is poorly studied, and none of the putative L-rhamnose pathway genes or enzymes have been characterized. This project aims to confirm the function of the putative L-rhamnose pathway genes and to identify which metabolite in the Lrhamnose pathway is the inducer of the L-rhamnose responsive regulator (RhaR) (Gruben et al., 2014). After identification of the candidates, deletion mutants for these genes were obtained. Growth profile result showed no or only minor growth for all of the metabolic mutants. To study the effect of deletion of these genes in more detail, transcriptomics analysis of the reference strain and the KO strains ΔlraA, ΔlraB, ΔlraC and ΔrhaR have been done. The results indicate that L-rhamnose, L-rhamnono-Ylactone and L-rhamnonate are not the inducers of RhaR. Further experiments will be required in order to determine if the inducer is located at the end of the metabolic pathway.
Full conference title:
- Asperfest 14 (2017)