Ene-reductase transformation of massoia lactone to ?-decalactone in a continuous-fow reactor

The demand for natural food favorings increases every year. Biotransformation has become an attractive approach to obtain natural products. In this work, enantiomerically pure (R)-(+)-?decalactone was obtained by reduction of the C=C double bond of natural massoia lactone in a continuous-fow reactor. Of 13 diferent ene-reductases isolated, purifed and tested, OYE3 was found to be the most efcient biocatalyst. The selected biocatalyst, either in the form of purifed enzyme, cell lysate, whole cells or immobilized cells, was tested in the batch system as well as in the packedbed fow bioreactor. The biotransformation performed in batch mode, using Ca2+-alginate immobilized cells of Escherichia coli BL21(DE3)/pET30a-OYE3, furnished the desired product with complete conversion in 30 min. The process was intensifed using a continuous-fow reactor-membrane fltration system (fow 0.1 mL/min, substrate concentration 10 mM, pH 7, 24 °C) with cell lysate as biocatalyst combined with a cofactor regeneration system, which allowed obtaining> 99% bioconversion of massoia lactone.