Hydroperoxide production from linoleic acid by heterologous <i>Gaeumannomyces graminis tritici</i> lipoxygenase:Optimization and scale-up

Linoleic acid was converted into hydroperoxides by a Gaeumannomyces graminis tritici lipoxygenase produced recombinantly in Trichoderma reesei. Hydroperoxide production was optimized using a face-centred experimental design in order to study the effects of pH, temperature and time on the conversion of linoleic acid into four regioisomeric hydroperoxyoctadecadienoic acids (HPODE): 13-(Z,E)-, 9-(E,Z)-, 13-(E,E)-, 9-(E,E)-HPODE. Fitting equations described satisfactorily the system behavior and showed that reaction time was the most influencing independent variable. A set of independent variables (pH = 6.7, temperature = 23.9 °C and time = 18 h) allowed to obtain high yields of hydroperoxides (88.0%) with a good selectivity for the 13-(Z,E)-HPODE isomer (47.4%) when the initial substrate concentration was 10 g/L. The production was further investigated using industrially relevant linoleic acid concentrations (100–300 g/L) leading to HPODE yields of ∼40% and the volumetric productivity 3.6 g/(L h), and a selectivity for 13-(Z,E)-HPODE of around 74%