Biomanufacturing of 2-Pyrone-4,6-dicarboxylic Acid by an Engineered Corynebacterium glutamicum Cell Factory
2-Pyrone-4,6-dicarboxylic acid (PDC) is a promising pseudo-aromatic bio-based monomer for the production of biodegradable polyesters. Here, we combined metabolic engineering with fermentation process optimization to establish efficient de novo PDC biosynthesis in Corynebacterium glutamicum. To enhance the availability of protocatechuic acid (PCA), the direct precursor of PDC, endogenous PCA degradation was blocked, and precursor supply through the shikimate pathway was strengthened. Subsequently, the ligABC cluster from Sphingomonas paucimobilis SYK-6 was heterologously introduced to enable PDC formation from glucose. Medium screening identified a corn steep liquor-containing formulation that increased the PDC titer by 1.4-fold in shake-flask cultures. Further optimization of corn steep liquor concentration, dissolved oxygen, and glucose feeding rate in a 5-L bioreactor increased the PDC titer to 71.1 g/L at 90 h, with an average productivity of 0.8 g/L/h, the highest productivity for C. glutamicum-based PDC production reported to date.