Production of 8-hydroxy-9,12(Z,Z)-octadecadienoic acid from linoleic acid by recombinant cells expressing H1004A-C1006S variant of Aspergillus nidulans diol synthase

• H1004A-C1006S of Aspergillus nidulans diol synthase was 8-dioxygenase.
• Whole cells expressing the double-site variant converted linoleic acid to 8-HPODE.
• 8-HPODE was reduced to 8-HODE by adding TECP-HCl as a reducing agent.
• Whole cells produced 5.0 g l−1 8-HODE from 16.5 g l−1 linoleic acid for 1 h.

An H1004A-C1006S variant of Aspergillus nidulans diol synthase was identified as an 8-dioxygenase. Whole recombinant Escherichia coli cells expressing the double-site variant showed the highest activity for converting linoleic acid to 8-hydroperoxy-9,12(Z,Z)-octadecadienoic acid (8-HPODE), which in turn was reduced to 8-hydroxy-9,12(Z,Z)-octadecadienoic acid (8-HODE) by the addition of a reducing agent. The optimization of 8-HPODE production was performed by response surface methodology, and the optimal conditions were pH 8.3, 27.2 °C, 22.7% dimethyl sulfoxide, 27.0 g l−1 cells, and 16.5 g l−1 linoleic acid in a 100 ml baffled flask containing a 10 ml reaction mixture with agitation at 236 rpm. The reduction of 8-HPODE to 8-HODE was highest when Tris(2-carboxyethyl)phosphine hydrochloride (TECP-HCl) was added at a final concentration of 25 mM. Under the optimized reaction and reduction conditions, whole cells expressing H1004A-C1006S variant of A. nidulans diol synthase produced 5.0 g l−1 8-HODE for 1 h without the formation of di-hydroxy fatty acids. This is the first report of the biotechnological production of 8-HODE.

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