Ustilago maydis Metabolic Characterization and Growth Quantification with a Genome-Scale Metabolic Model

Ustilago maydis is an important plant pathogen causing corn-smut disease and an effective biotechnological production host. The lack of a comprehensive metabolic overview hinders a full understanding of the organism’s environmental adaptation and a full use of its metabolic potential. Here, we report the first genome scale metabolic model (GSMM) of Ustilago maydis (iUma22) for the simulation of metabolic activities. iUma22 was reconstructed from sequencing and annotation using PathwayTools, the biomass equation was derived from literature values and from the codon composition. The final model contains over 25% of annotated genes (6,909) in the sequenced genome. Substrate utilization was corrected by Biolog-Phenotype arrays and exponential batch cultivations were used to test growth predictions. The growth data revealed a metabolic phenotype shift at high glucose uptake rates and the model allowed its quantification. A pan-genome of four different U. maydis strains revealed missing metabolic pathways in iUma22. The new model allows studies of metabolic adaptations to different environmental niches as well as for biotechnological applications.