Improving the productivity of propionic acid with FBB-immobilized cells of an adapted acid-tolerant Propionibacterium acidipropionici.

Propionic acid is an important short-chain fatty acid with many applications, but its large-scale bioproduction was hindered by the low productivity. An adapted acid-tolerant Propionibacterium acidipropionici CGMCC 1.2230 strain was selected to produce propionic acid with a relatively high productivity (0.29 g/(Lh)) in the free-cell fermentation. Further immobilized-cell fermentation in fibrous-bed bioreactor (FBB) supported high-level repeated batch fermentations with a high productivity of 0.96 g/(Lh). The FBB also presents the potential to increase final propionic acid concentration by using glucose feeding strategy. The propionic acid concentration was increased to 51.2g/L in the fed-batch fermentation with the productivity of 0.71 g/(Lh). By adopting the above strategies, sugarcane bagasse hydrolysate could support the production of propionic acid with high productivity in the repeat-batch and fed-batch fermentations. The present work would pave one road to the accomplishment of large-scale bioproduction of propionic acid from renewable resources.