Production of 13S-hydroxy-9(Z)-octadecenoic acid from linoleic acid by whole recombinant cells expressing linoleate 13-hydratase from Lactobacillus acidophilus

Linoleate 13-hydratase from Lactobacillus acidophilus LMG 11470 converted linoleic acid to hydroxyl fatty acid, which was identified as 13S-hydroxy-9(Z)-octadecenoic acid (13-HOD) by GC-MS and NMR. The expression of linoleate 13-hydratase gene in Escherichia coli was maximized by using pACYC plasmid and super optimal broth with catabolite repression (SOC) medium containing 40 mM Mg2+. To optimize induction conditions, recombinant cells were cultivated at 37 °C, 1 mM isopropyl-β-d-thiogalactopyranoside was added at 2 h, and the culture was further incubated at 16 °C for 18 h. Recombinant cells expressing linoleate 13-hydratase from L. acidophilus were obtained under the optimized expression conditions and used for 13-HOD production from linoleic acid. The optimal reaction conditions were pH 6.0, 40 °C, 0.25% (v/v) Tween 40, 25 g l−1 cells, and 100 g l−1 linoleic acid, and under these conditions, whole recombinant cells produced 79 g l−1 13-HOD for 3 h with a conversion yield of 79% (w/w), a volumetric productivity of 26.3 g l−1 h−1, and a specific productivity of 1.05 g g-cells−1 h−1. To the best of our knowledge, the recombinant cells produced hydroxy fatty acid with the highest concentration and productivity reported so far.