Ustilaginaceae Biocatalyst for Co-Metabolism of CO2-Derived Substrates toward Carbon-Neutral Itaconate Production

Abstract

The family Ustilaginaceae (belonging to the smut fungi) are known for their plant pathogenicity. Despite the fact that these plant diseases cause agricultural yield reduction, smut fungi attracted special attention in the field of industrial biotechnology. Ustilaginaceae show a versatile product spectrum such as organic acids (e.g., itaconate, malate, succinate), polyols (e.g., erythritol, mannitol), and extracellular glycolipids, which are considered value-added chemicals with potential applications in the pharmaceutical, food, and chemical industries. This study focused on itaconate as a platform chemical for the production of resins, plastics, adhesives, and biofuels. During this work, 72 different Ustilaginaceae strains from 36 species were investigated for their ability to (co-) consume the CO2-derived substrates acetate and formate, potentially contributing toward a carbon-neutral itaconate production. The fungal growth and product spectrum with special interest in itaconate was characterized. Ustilago maydis MB215 and Ustilago rabenhorstiana NBRC 8995 were identified as promising candidates for acetate metabolization whereas Ustilago cynodontis NBRC 7530 was identified as a potential production host using formate as a co-substrate enhancing the itaconate production. Selected strains with the best itaconate production were characterized in more detail in controlled-batch bioreactor experiments confirming the co-substrate utilization. Thus, a proof-of-principle study was performed resulting in the identification and characterization of three promising Ustilaginaceae biocatalyst candidates for carbon-neutral itaconate production contributing to the biotechnological relevance of Ustilaginaceae.

Itaconic acid production by co-feeding ofUstilago maydis: a combined approach of experimental data, design of experiments and metabolic modeling

“…Since the reached yield did not differ significantly from the model prediction, the validation was considered as successful, indicating that the model has an accurate predictive power regarding the yield for a defined substrate combination within the model ranges. Moreover, the comparison to a glucose reference with a similar total carbon amount showed that acetate has a positive effect on the itaconic acid production, which was already indicated in previous experiments [15].…”

“…By combining metabolic engineering strategies and an integrated process design, a maximum itaconic acid titer of 220 g L −1 was achieved, while for the last 70 years, itaconic acid has been produced using A. terreus , reaching titers of 130 g L −1 [11]. The current biotechnological processes for itaconic acid production with A. terreus and U. maydis are based on carbohydrates, such as molasses and glucose [10, 15]. With the overarching goal of a carbon-neutral itaconic acid production process, Ullmann et al [15] investigated the potential to (co-)consume CO 2 -derived C2 compounds such as acetate.…”

Seventeen Ustilaginaceae High-Quality Genome Sequences Allow Phylogenomic Analysis and Provide Insights into Secondary Metabolite Synthesis

“…U. maydis does not only show a broad product spectrum, but also metabolizes a range of renewable carbon sources, which, apart from sugars, also include the monomers acetate, galacturonic acid, glycerol, and xylose, as well as the polymers cellulose, pectin, lignin, and xylan [ 8 , 9 , 10 , 11 ]. Among the Ustilaginaceae, U. maydis is the best-studied species in plant pathogenicity and biotechnology, and is a model organism in cell biology [ 12 ].…”

Three Sides of the Same Coin: Combining Microbial, Enzymatic, and Organometallic Catalysis for Integrated Conversion of Renewable Carbon Sources

“…From the possible C1‐compounds described above, formate is non‐volatile and non‐toxic. In addition, formate is not a passive carbon‐storage compound but a valuable animal 55 and microbial 56 co‐feed. To achieve this upgrading, co‐application of an organometallic catalyst is necessary.…”