Hydroxytyrosol production from L-DOPA by engineered Escherichia coli co-expressing L-amino acid deaminase, α-keto acid decarboxylase, aldehyde reductase and glucose dehydrogenase with NADH regeneration

Hydroxytyrosol, a phenolic compound derived from olives, is conducive to human health and is widely used in food additives and cosmetic industries due to its significant antioxidant activity and cancer prevention proper-ties. In this research, we designed and constructed a nearly irreversible and efficient bio-catalysis cascade re-action for hydroxytyrosol production from L-3,4-dihydroxy-phenylalanine. The recombinant Escherichia coli cells were constructed by co-expressing L-amino acid deaminase from Cosenzaea myxofaciens, alpha-keto acid decarbox-ylase from Proteus mirabilis, aldehyde reductase from Escherichia coli (DE3) and glucose dehydrogenase from Bacillus subtilis. The glucose dehydrogenase catalyzed the dehydrogenation of co-substrate (glucose) to achieve the regeneration of NADH, which was an indispensable reductant for producing hydroxytyrosol. Subsequently, the expression of these enzymes was coordinated using a strategy of combining two different compatible plas-mids. Finally, the production of hydroxytyrosol reached at 55.53 mM (8.55 g/L) within 6 h under the optimum biotransformation conditions.

Automated summary

In this research, a bio-catalysis cascade reaction was designed and constructed to produce hydroxytyrosol from L-3,4-dihydroxyphenylalanine. The recombinant Escherichia coli cells were used to express multiple enzymes, and glucose dehydrogenase was used to regenerate NADH, an essential reductant. The production of hydroxytyrosol reached a high yield within a short period of time under optimal conditions.