A new process for obtaining hydroxytyrosol using transformed Escherichia coli whole cells with phenol hydroxylase gene from Geobacillus thermoglucosidasius

► Effective method to hydroxylate tyrosol into the high-added-value compound hydroxytyrosol. ► Transformants achieved 100% bioconversion of monophenols in high concentration (5 mM). ► Represents an increase in concentration and yield, compared with previous data. ► The cell biocatalyst retains 50% of its hydroxylating capacity after 5 cycles.