Optical resolution of racemic citronellol via a double coupling system in an interface bioreactor

A double coupling system consisting of acetyl coenzyme A [acetyl-CoA] formation via the metabolism of glucose and the subsequent acetylation of a primary alcohol by acetyl-CoA with the aid of alcohol acetyltransferase [AATFase], was applied for the optical resolution of racemic citronellol. Pichia kluyveri IFO 1165 was superior for the optical resolution of racemic citronellol and provided (S)-citronellyl acetate and (R)-citronellol with high enantioselectivity and yield. The strain also exhibited excellent resistance to high concentrations of citronellol, i.e., it could maintain metabolism and enantioselective acetylation even in the presence of 30% citronellol. The coupling system using P. kluyveri IFO 1165 was applied to two new types of interface bioreactors, tentatively referred to as bead-packed and multistory interface bioreactors. Using the latter bioreactor, (S)-citronellyl acetate and (R)-citronellol were produced in large amounts at high enantioselectivity and yield.