Improved Production of Arachidonic Acid by Combined Pathway Engineering and Synthetic Enzyme Fusion in .

Arachidonic acid (ARA， C20:4) is a typical ω-6 polyunsaturated fatty acid with special functions. Using as an unconventional chassis， we previously showed the performance of the Δ-6 pathway in ARA production. However， a significant increase in the Δ-9 pathway has rarely been reported. Herein， the Δ-9 pathway from was constructed via pathway engineering， allowing us to synthesize ARA at 91.5 mg L. To further improve the ARA titer， novel enzyme fusions of Δ-9 elongase and Δ-8 desaturase were redesigned in special combinations containing different linkers. Finally， with the integrated pathway engineering and synthetic enzyme fusion， a 29% increase in the ARA titer， up to 118.1 mg/L， was achieved using the reconstructed strain RH-4 that harbors the rigid linker (GGGGS). The results show that the combined pathway and protein engineering can significantly facilitate applications of .