ALCOHOL-DEHYDROGENASE-CATALYZED PRODUCTION OF CHIRAL HYDROPHOBIC ALCOHOLS - A NEW APPROACH LEADING TO A NEARLY WASTE-FREE PROCESS

1`The enantioselective enzyme-catalyzed reduction of ketones in an enz yme membrane reactor coupled to a membrane-based extractive product se paration was developed for the production of chiral hydrophobic alcoho ls. Enantiomerically pure (S)-1-phenylpropan-2-ol, (S)-4-phenylbutan-2 -ol and (S)-6-methylhept-5-en-2-ol (sulcatol) were obtained with high purities. In spite of low substrate concentrations (9-12 mM) space-tim e yields higher than 100 g/(1 . d) and concentrated product solutions were obtained. Formate-dehydrogenase-catalyzed regeneration of cofacto r, together with process-integrated recycling of cofactor, led to tota l-turnover numbers for NAD(+) of up to 1350 mol(P)/mol(NAD), which mea ns a 25-fold increase in comparison with standard techniques without c ofactor retention. Because of the closed-loop design of the reactor th e process can be run almost without waste, yielding the pure chiral al cohol and CO2.