Chemoenzymatic Cascade Conversion of Linoleic Acid into a Secondary Fatty Alcohol Using a Combination of 13S-Lipoxygenase, Chemical Reduction, and a Photo-Activated Decarboxylase

Abstract

Linoleic acid serves as a starting material in the production of various oleochemicals. Here, we have investigated the transformation of linoleic acid into 13S-hydroxy-(9Z,11E)-octadecadienoic acid (13-HOD) (17) and 6S-hydroxy-(7E,9Z)heptadecadiene (6-HHD) (18) by using 13S-lipoxygenase from Pseudomonas aeruginosa (Pa-LOX) and photo-activated decarboxylase from Chlorella variabilis NC64A (Cv-FAP). Remarkably, the recombinant Escherichia coli expressing Pa-LOX was able to produce 13S-hydroperoxy-(9Z,11E)-octadecadienoic acid (16) at a maximum rate of 850 mu mol/g dry cells/min. This allowed the accumulation of 13-HOD (17) to 161 mM (48 g/L) concentration from 200 mM linoleic acid in the reaction medium within 3.5 h. We have also demonstrated that the fatty acids, including C=C bonds in cis- and trans-forms [e.g., 13-HOD (17)], were subjected to photo-activated decarboxylation by Cv-FAP. Ultimately, the secondary fatty alcohol [i.e., 6-HHD (18)] was produced from linoleic acid through the chemo/enzymatic cascade transformation, consisting of dioxygenation of linoleic acid by intracellular Pa-LOX and reduction of the hydroperoxy fatty acid (16) by Tris(2-carboxyethyl) phosphine or cysteine. Moreover, the photoactivated decarboxylation of the hydroxy fatty acid (17) by intracellular Cv-FAP achieved a conversion of ca. 74% in a one-pot process. This study will contribute to the valorization of gamma-linolenic and arachidonic acid, as well as linoleic acid, which are the substrates of Pa-LOX.