Calcium Alginate Bead Immobilization of Cells Containing Tyrosine Ammonia Lyase Activity for Use in the Production of p-Hydroxycinnamic Acid

An Escherichia coli catalyst with tyrosine ammonia lyase activity (TAL) has been stabilized for repeated use in batch conversions of high tyrosine solids to p‐hydroxycinnamic acid (pHCA). The TAL biocatalyst was stabilized by controlling the reaction pH to 9.8 ± 0.1 and immobilizing the cells within a calcium alginate matrix that was cross‐linked with glutaraldehyde and polyethyleneimine (GA/PEI). We found a GA range where the bead‐encapsulated TAL was not inactivated, and the resulting cross‐linking provided the beads with the mechanical stability necessary for repeated use in consecutive batch reactions with catalyst recycle. The GA/PEI calcium alginate TAL catalyst was used in 41 1‐L batch reactions where 50 g L−1 tyrosine was converted to 39 ± 4 g L−1 pHCA in each batch. The practical usefulness and ease of this process was demonstrated by scaling up the TAL bead immobilization and using the immobilized TAL catalyst in four 125‐L bioconversion reactions to produce over 12 kg of purified pHCA.