Biomanufacturing ofγ-linolenic acid-enriched galactosyldiacylglycerols:Challenges in microalgae and potential in oleaginous yeasts

γ-Linolenic acid-enriched galactosyldiacylglycerols(GDGs-GLA),as the natural form ofγ-linolenic acid in microalgae,have a range of functional activities,including anti-inflammatory,antioxidant,and anti-allergic properties.The low abundance of microalgae and the structural stereoselectivity complexity impede microalgae extraction or chemical synthesis,resulting in a lack of supply of GDGs-GLA with a growing demand.At present,there is a growing interest in engineering oleaginous yeasts for mass production of GDGs-GLA based on their ability to utilize a variety of hydrophobic substrates and a high metabolic flux toward fatty acid and lipid(triacylglycerol,TAG)production.Here,we first introduce the GDGs-GLA biosynthetic pathway in microalgae and challenges in the engineering of the native host.Subsequently,we describe in detail the applications of oleaginous yeasts with Yarrowia lipolytica as the representative for GDGs-GLA biosynthesis,including the development of synthetic biology parts,gene editing tools,and metabolic engineering of lipid biosynthesis.Finally,we discuss the development trend of GDGs-GLA biosynthesis in Y.lipolytica.