Biosynthesis of propionic acid from whey permeate and corn steep liquor by Propionibacterium freudenreichii subsp ATCC 6207 and partial purification using ion exchange cryogels

Propionic acid (PA) is industrially produced using raw materials derived from petroleum. In search of more sustainable processes, this work investigated the production of propionic acid (PA) by fermentation using whey permeate (WP) and corn steep water (CSL), with the strain Propionibacterium freudenreichii subsp ATCC 6207. Two strategies of fermentation were compared: one in batch and the other fed batch, carried out in a 5 L bioreactor at 30 °C, with pH control. Furthermore, in fed-batch fermentation, lactose concentration was controlled. The study revealed that batch fermentation was more efficient in producing propionic acid (PA). After 72 h, the concentration reached 13.10 g L⁻¹, with a yield of 0.335 g g⁻¹ and productivity of 0.182 g L⁻¹ h⁻¹. The research addressed the PA purification by ion exchange chromatography, using cryogels functionalized with taurine (Tau-cryogel). Tests at different pH (4 to 7) showed greater PA adsorption on the cryogel at pH 4 (256.13 mg g⁻¹), with recovery of 59.7% and lower adsorption of acetic acid (29.34 mg g⁻¹), indicating promising selectivity in purification. This study shows the feasibility of using byproducts such as WP and CSL in the production of PA and the potential of applying ion exchange cryogels in its purification.