Laboratory evolution strategies for improving lipid accumulation in Yarrowia lipolytica

Oleaginous microorganisms are of high biotechnological interest being considered as alternative sources of oil (single cell oil-SCO). Current research for increasing productivity of oleaginous microorganisms is focused on the overexpression of genes implicated in lipid synthesis, the inactivation of genes implicated in storage lipid turnover, and on the suppression of competitive to lipid biosynthesis pathways. An alternative strategy, described here, relies on evolution of Yarrowia lipolytica under alternating environments that promote growth, encourage storage lipid synthesis, and reward high energy-containing cells. Derived populations were characterized biochemically, especially on their ability to accumulate lipids, and compared with the starting strain. Interestingly, lipid-accumulating ability early in the evolution was decreased compared with the starting strain. Subsequently, oleaginous lineages dominated, leading to populations able to accumulate lipids in high amounts. A population obtained after 77 generations was able to accumulate 44% w/w of lipid, which was 30% higher than that of the starting strain. We conclude that evolution-based strategies can be utilized as a robust tool for improving lipid accumulation capacity in oleaginous microorganisms.