Yarrowia lipolytica as a Platform for Punicic Acid Production.

Punicic acid (PuA) is a polyunsaturated fatty acid with significant medical, biological, and nutraceutical properties. The primary source of punicic acid is the pomegranate seed oil obtained from fruits of trees that are mainly cultivated in subtropical and tropical climates. To establish sustainable production of PuA, various recombinant microorganisms and plants have been explored as platforms with limited efficiencies. In this study, the oleaginous yeast Yarrowia lipolytica was employed as a host for PuA production. First, growth and lipid accumulation of Y. lipolytica were evaluated in medium supplemented with pomegranate seed oil, resulting in the accumulation of lipids up to 31.2%, consisting of 22% PuA esterified in the fraction of glycerolipids. In addition, lipid-engineered Y. lipolytica strains, transformed with the bifunctional fatty acid conjugase/desaturase from Punica granatum (PgFADX), showed the ability to accumulate PuA de novo. PuA was detected in both polar and neutral lipid fractions, especially in phosphatidylcholine and triacylglycerols. Promoter optimization for PgFADX expression resulted in improved accumulation of PuA from 0.9 to 1.8 mg/g of dry cell weight. The best-producing strain expressing PgFADX under the control of a strong erythritol-inducible promoter produced 36.6 mg/L PuA. These results demonstrate that the yeast Y. lipolytica is a promising host for PuA production.

Enhancing very long chain fatty acids production in Yarrowia lipolytica.

BACKGROUND: Very long chain fatty acids (VLCFA) and their derivatives are industrially attractive compounds. The most important are behenic acid (C22:0) and erucic acid (C22:1Δ13), which are used as lubricants, and moisturizers. C22:0 and C22:1Δ13 have also potential for biofuel production. These fatty acids are conventionally obtained from plant oils. Yarrowia lipolytica is an oleaginous yeast with a long history of gene manipulations resulting in the production of industrially interesting compounds, such as organic acids, proteins, and various lipophilic molecules. It has been shown previously that it has potential for the production of VLCFA enriched single cell oils. RESULTS: The metabolism of Y. lipolytica was redesigned to achieve increased production of VLCFA. The effect of native diacylglycerol acyltransferases of this yeast YlLro1p, YlDga1p, and YlDga2p on the accumulation of VLCFA was examined. It was found that YlDga1p is the only enzyme with a beneficial effect. Further improvement of accumulation was achieved by overexpression of 3-ketoacyl-CoA synthase (TaFAE1) under 8UAS-pTEF promoter and blockage fatty acid degradation pathway by deletion of YlMFE1. The best-producing strain YL53 (Δmfe, pTEF-YlDGA1, 8UAS-pTEF-TaFAE1) produced 120 µg of very long chain fatty acids per g of produced biomass, which accounted for 34% of total fatty acids in biomass. CONCLUSIONS: Recombinant strains of Y. lipolytica have proved to be good producers of VLCFA. Redesign of lipid metabolism pathways had a positive effect on the accumulation of C22:1Δ13 and C22:0, which are technologically attractive compounds.