The present invention relates to the field involved in the production of phenylbutanone or phenylbutanone derivative compounds, such as frambinone or zingerone, and in particular strains genetically modified to express a benzalacetone reductase.

The disclosure provides a metabolic pathway for producing a metabolite, the metabolic pathway having a co-factor purge valve system for recycling a cofactor used in the metabolic pathway.

The disclosure relates to engineered enone reductase polypeptides having improved properties, polynucleotides encoding the engineered polypeptides, related vectors, host cells, and methods for making the engineered enone reductase polypeptides. The disclosure also provides methods of using the engineered enone reductase polypeptides for chemical transformations.