Production of Isopropyl cis-6-Hexadecenoate by Regiospecific Desaturation of Isopropyl Palmitate by a Double Mutant of a Rhodococcus Strain

Resting cells of a double mutant noted as KSM-MT66, derived from Rhodococcus sp. strain KSM-B-3 by UV irradiation, were found to cis-desaturate isopropyl hexadecanoate, yielding isopropyl cis-6-hexadecenoate. Addition of sodium glutamate (1.0%), MgSO₄ (2 mM), and thiamine (2 mM) increased the productivity of the unsaturated product in phosphate buffer. Optimal temperature and pH for the reaction were around 26°C and 7, respectively. Under the optimized conditions, more than 50 g/l of isopropyl cis-6-hexadecenoate was produced after a 3-day incubation by resting cells of the mutant. Thus, cis-6-hexadecenoic acid, the main component of human sebaceous lipids, can be manufactured economically by the rhodococcal bioconversion.