Sustainable Production of Propionic Acid from Xylose and Glycerol by Acidipropionibacterium acidipropionici DSM 4900: A Biorefinery Approach

Propionic acid (PA) is a valuable chemical with wide industrial applications, and its sustainable production via microbial fermentation has gained increasing attention. This study aimed to develop and improve a bioprocess for PA production using Acidipropionibacterium acidipropionici DSM 4900 and renewable carbon sources, namely xylose and glycerol. Shake-flask and bioreactor experiments were conducted to evaluate the effects of substrate ratios and operational strategies on process performance. Among the tested conditions, the fed-batch bioreactor using glycerol as the main substrate showed the best results, reaching a final PA concentration of 24.5 g/L, productivity of 0.18 g/(L·h), yield of 0.57 g/g, and bioconversion efficiency of 71%. These findings highlight the potential of optimizing substrate composition and feeding strategies to enhance microbial catalysis and process efficiency. This work advances current knowledge by revealing the synergy between xylose and glycerol co-utilization and demonstrating that integrated process design, combining redox-balanced substrates with fed-batch operation, can overcome end-product inhibition and enhance carbon flux toward propionic acid synthesis. Overall, this study demonstrates the feasibility of using low-cost, renewable feedstocks for PA production, contributing to the development of sustainable and circular biorefinery platforms in line with green chemistry and process intensification principles.