| Summary: | In the human body, docosahexaenoic acid (DHA) contained in fish oil is converted to trace amounts of specialized pro-resolving mediators (SPMs) as the principal bioactive metabolites for their pharmacological effects. Protectin Dx (PDX), an SPM, is an important medicinal compound with biological activities such as modulation of endogenous antioxidant systems, inflammation pro-resolving action, and inhibition of influenza virus replication. Although it can be biotechnologically synthesized from DHA, it has not yet been produced quantitatively. Here, we found that 15<i>S</i>-lipoxygenase from <i>Burkholderia thailandensis</i> (BT 15<i>S</i>LOX) converted 10<i>S</i>-hydroxydocosahexaenoic acid (10<i>S</i>-HDHA) to PDX using enzymatic reactions, which was confirmed by LC-MS/MS and NMR analyses. Thus, whole-cell reactions of <i>Escherichia coli</i> cells expressing BT 15<i>S</i>LOX were performed in flasks to produce PDX from lipase-treated DHA-enriched fish oil along with <i>E. coli</i> cells expressing <i>Mus musculus</i> (mouse) 8<i>S</i>-lipoxygenase (MO 8<i>S</i>LOX) that converted DHA to 10<i>S</i>-HDHA. First, 1 mM DHA (DHA-enriched fish oil hydrolysate, DFOH) was obtained from 455 mg/L DHA-enriched fish oil by lipase for 1 h. Second, <i>E. coli</i> cells expressing MO 8<i>S</i>LOX converted 1 mM DHA in DFOH to 0.43 mM 10<i>S</i>-HDHA for 6 h. Finally, <i>E. coli</i> cells expressing BT 15<i>S</i>LOX converted 0.43 mM 10<i>S</i>-HDHA in MO 8<i>S</i>LOX-treated DFOH to 0.30 mM (108 mg/L) PDX for 5 h. Consequently, DHA-enriched fish oil at 455 mg/L was converted to 108 mg/L PDX after a total of 12 h (conversion yield: 24% (<i>w</i>/<i>w</i>); productivity: 4.5 mg/L/h). This study is the first report on the quantitative production of PDX via biotechnological approaches.
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