Production of high hydroxytyrosol yields via tyrosol conversion by Pseudomonas aeruginosa immobilized resting cells

An immobilized whole cell system was successfully performed to produce the most powerful antioxidant, hydroxytyrosol. Bioconversion of tyrosol into hydroxytyrosol was achieved via the immobilization of Pseudomonas aeruginosa resting cells in calcium alginate beads. Immobilization was advantageous as it allows immobilized cells to tolerate a greater tyrosol concentration than free cells. The bioconversion yield reached 86% in the presence of 5 g L-1 of tyrosol when cells immobilized in alginate beads were carried out in single batches. Evaluation of kinetic parameters showed the maintenance of the same catalytic efficiency expressed as K-cat/K-m for both free and immobilized cells. The use of immobilized cells in repeated batches demonstrated a notable activity stabilization since the biocatalyst reusability was extended for at least four batches with a molar yield greater than 85%.