Production of 8,11‐dihydroxy fatty acids from oleic and palmitoleic acids by Escherichia coli cells expressing variant 6,8‐linoleate diol synthases from Penicillium oxalicum

Abstract

Recombinant Escherichia coli cells expressing 8,11‐linoleate diol synthase (LDS) from Penicillium chrysogenum convert oleic and palmitoleic acids to 8‐hydroperoxy‐9(Z)‐octadecenoic acid (HPOME) and 8‐hydroperoxy‐9(Z)‐hexadecenoic acid (HPHME) only, respectively. However, recombinant E. coli cells expressing Q889A variant 6,8‐LDS from Penicillium oxalicum as an 8,11‐LDS converted oleic and palmitoleic acids to 8,11‐dihydroxy‐9(Z)‐octadecenoic acid (DiHOME) and 8,11‐dihydroxy‐9(Z)‐hexadecenoic acid (DiHHME), respectively, which were identified using liquid chromatography–tandem mass spectrometry analysis. To select suitable variants for producing these compounds, position 889 of 6,8‐LDS from P. oxalicum was substituted with other amino acids, and recombinant E. coli cells expressing Q889L and Q889A variants were chosen as the best biocatalysts for producing 8,11‐DiHOME and 8,11‐DiHHME, respectively. The optimal conditions for producing 8,11‐DiHOME or 8,11‐DiHHME using cells expressing Q889L or Q889A variant 6,8‐LDS were pH 6.5 and 30 °C with 5% (v/v) dimethyl sulfoxide, 60 g L−1 cells, and 10 g L−1 oleic acid or 7.5 g L−1 palmitoleic acid, respectively. Under these conditions, 10.7 g L−1 8,11‐DiHOME and 8.1 g L−1 8,11‐DiHHME were produced for 1.5 h with molar yields of 96.4% and 96.2% and productivities of 7.1 and 5.4 g L−1 h−1, respectively. The molar yields and concentrations of 8,11‐DiHOME and 8,11‐DiHHME were highest among those of other reported DiHOMEs and DiHHMEs. To the best of our knowledge, this is the first quantitative production of 8,11‐DiHOME and 8,11‐DiHHME.