BACKGROUNDLow permeability of substrates across the cell membrane, cofactor regeneration and product inhibition are some drawbacks of (+)-nootkatone bioconversion. The aim of this work was to evaluate and enhance the bioconversion of (+)-valencene to (+)-nootkatone with Yarrowia lipolytica in a partitioning bioreactor using orange essential oil as the dispersed phase. RESULTSPreliminary experiments in shake flasks allowed enhancing (+)-nootkatone bioconversion to obtain favorable operating conditions (0.2% w/v of CTAB, 2.0 mmol L-1 of niacin and 11.5 g L-1 of biomass) to produce 420.9 mg L-1. Bioreactor experiments in a two-phase system using 0.2% (w/v) of CTAB, 2.0 mmol L-1 of niacin and 22.5 g L-1 of biomass produced a maximum (+)-nootkatone concentration of 619.8 mg L-1 which was around the product inhibition concentration. Nevertheless, the partitioning three-phase system using orange essential oil overcame product inhibition, obtaining concentrations up to 852.3 mg L-1. CONCLUSIONSThis is the first report of a wild type Y. lipolytica with the enzymatic machinery to carry out this bioconversion. The multiphase partitioning bioreactor concept seems to have good potential for enhancing the productivity of (+)-nootkatone. The bioconversion approach presents an attractive way to produce and recover (+)-nootkatone in situ using a natural (+)-valencene source. (c) 2015 Society of Chemical Industry