Bioproduction of propionic acid using levulinic acid by engineered .

The present study elaborates on the propionic acid (PA) production by the well-known microbial cell factory EM42 and its capacity to utilize biomass-derived levulinic acid (LA). Primarily, the EM42 strain was engineered to produce PA by deleting the methylcitrate synthase (PrpC) and propionyl-CoA synthase (PrpE) genes. Subsequently, a LA-inducible expression system was employed to express (encoding thioesterase) from and (encoding propionyl-CoA: succinate CoA transferase) from to improve the PA production by up to 10-fold under flask scale cultivation. The engineered EM42:ΔCE: was used to optimize the bioprocess to further improve the PA production titer. Moreover, the fed-batch fermentation performed under optimized conditions in a 5 L bioreactor resulted in the titer, productivity, and molar yield for PA production of 26.8 g/L, 0.3 g/L/h, and 83%, respectively. This study, thus, successfully explored the LA catabolic pathway of as an alternative route for the sustainable and industrial production of PA from LA.