Cryogel‐based co‐culture of Lactobacillus paracasei and Lactobacillus buchneri towards phenyllactic acid bioproduction: fundamental hydrodynamics and biotransformation characteristics

Abstract BACKGROUND Phenyllactic acid is an important monomer for bioplastics, food preservative, feed additive and pharmaceutical agent. However, bioproduction of phenyllactic acid suffers drawbacks regarding the high cost of substrates, poor efficiency and yield of fermentation or conversion, and therefore new bioproduction strategies need to be investigated. RESULTS In this work, bioproduction of phenyllactic acid was developed by employing semi‐hydrophobic cryogels as cell entrapment matrices to co‐culture Lactobacillus paracasei and L. buchneri strains, and the obtained cell‐loaded cryogels were used as biocatalysts in the biotransformation from phenylalanine. Flow characteristics and permeabilities of fermentation broths through cryogels, co‐culture performance and biotransformation characteristics were studied. Permeabilities of cell‐free fermentation broths through the cryogel bed were correlated as a function of concentrations of glucose and metabolites of organic acids. The flow rate versus pressure drop relationships for these bio‐based broths through cryogels were predicted successfully with a capillary‐based model. The cell growth was enhanced by cryogels and the maximum cell production of 40.6 g L −1 was achieved with cryogels. The maximum yield from phenylalanine of 1.0 mg mL −1 to phenyllactic acid was 39.6%, which was higher than that of 31.4% by co‐culture of L. casei and L. paracasei . CONCLUSION Flow of fermentation broths through cryogels is crucial to develop a novel cryogel‐based bioproduction strategy for phenyllactic acid and can be characterized by capillary‐based modeling. Semi‐hydrophobic cryogels could be an interesting class of immobilization matrices for high‐cell‐density co‐culture towards the green strategy with these new biocatalysts in phenyllactic acid bioproduction and thus have potential applications in industries. © 2022 Society of Chemical Industry (SCI).