Small scale biotransformation of food additive trans-2-hexenal to trans-2-hexenol by recombinant alcohol dehydrogenase and formate dehydrogenase produced in Escherichia coli

Aromatic compounds, such as green note volatiles, belong to highly demanded chemicals in food and cosmetics industries. Their production, isolation and purification often represents a difficult challenge. The natural sources are often scarce and difficult to process, while chemical synthesis produces forms that do not occur naturally or even burden the environment. Production of aromatic compounds by recombinant enzymes have proven to represent the best of two worlds, as it enables preparation of economically sufficient quantities of the product while keeping its quality at required levels. The aim of our work was to develop sustainable laboratory-scale processes allowing production of two key enzymes used in biotransformation of highly valued, but volatile and unstable, aromatic compound trans-2-hexenal to a more stable trans-2-hexenol. We also demonstrated the ability of alcohol dehydrogenase coupled to formate dehydrogenase to catalyse this conversion at desired levels in a one-pot reaction at conversion rates above 90 %.