Multienzyme cascade for synthesis of hydroxytyrosol via engineered Escherichia coli

Hydroxytyrosol, a fine chemical, is widely utilized in food and pharmaceutical industries. In this study, we constructed a pathway to produce hydroxytyrosol by co-expressing tyrosin-phenol lyase (TPL), L-amino acid dehydrogenase (aadL), α-keto acid decarboxylase (KAD), aldehyde reductase (yahK) and glucose dehydrogenase (gdh). We changed combinations between plasmids with different copy numbers and target genes, resulting in 84% increase in hydroxytyrosol production. The yield of hydroxytyrosol was further increased 89.3% by optimizing the temperature and pH. Finally, 55.3 mM hydroxytyrosol was produced within 14 h by fed-batch biotransformation. This study provides a novel approach for hydroxytyrosol production.