De novo synthesis of trans-10, cis-12 conjugated linoleic acid in oleaginous yeast Yarrowia Lipolytica

The linoleic acid isomerase gene from Propionibacterium acnes was expressed in Yarrowia lipolytica Polh. Codon usage optimization of the PAI and multi-copy integration significantly improved the expression level of PAI in Y. lipolytica. The percentage of trans-10, cis-12 CLA was six times higher in yeast carrying the codon-optimized gene than in yeast carrying the native gene. In combination with multi-copy integration, the production yield was raised to approximately 30-fold. The amount of trans-10, cis-12 CLA reached 5.9% of total fatty acid yield in transformed Y. lipolytica.This is the first report of production of trans-10, cis-12 CLA by the oleaginous yeast Y. lipolytica, using glucose as the sole carbon source through expression of linoleic acid isomerase from Propionibacterium acnes.Conjugated linoleic acid (CLA) is a generic term used to describe a mixture of positional and geometric isomers of linoleic acid (LA) with conjugated double bonds. In the past three decades, CLA has attracted much attention because of its biologically beneficial functions. These include anti-carcinogenic, anti-atherogenic, anti-diabetic, anti-inflammatory and anti-obesity properties in animal models and humans. To date, three CLA isomers have been demonstrated to possess beneficial effects individually: cis-9, trans-11 CLA, trans-10, cis-12 CLA and trans-9, trans-11 CLA. Different isomers have different effects on metabolism and act through different cell signaling pathways [1-3].In nature, CLA isomers occur in meat and dairy products derived from ruminants as a minor component of the lipid fraction [4]. Today, CLA, as a dietary supplement,is generally made from the LA of safflower and sunflower oils through alkaline isomerization in which additional functionally undetermined isomers are formed simultaneously [5,6]. Moreover, in the vast majority of the studies about CLA effectiveness on human volunteers, CLA mixtures rather than pure isomers have been used for supplementation an