Engineering triacylglycerol production from sugars in oleaginous yeasts.

Oleaginous yeasts natively produce surplus triacylglycerol lipid and can be engineered for higher yield and productivity. Most enzymatic steps of triacylglycerol production are characterized, but key parts of the pathway remain unknown. This introduces uncertainty to metabolic engineering strategy and the upper limit of achievable lipid yield. Here, we present our current understanding of the oleaginous yeast triacylglycerol biosynthesis pathway, review metabolic engineering strategies, and discuss bioprocess constraints on lipid production. We also present a simplified substrate allocation model capturing the interaction of percent lipid content on overall triacylglycerol yield, productivity, and fermentation cost, which should help frame achievable bioprocess metrics.