Metabolic engineering of Yarrowia lipolytica for the production of odd-chain fatty acids

International audience

anglais. Microbial oils are regarded as promising alternatives to fossil fuels with increasing environmental and energy concern. Odd-chain fatty acids (OCFAs) are a type of valuable lipids with various applications: biomarkers, intermediates in the production of flavor and fragrance compounds, fuels, and plasticizers. This study aims to efficiently improve the production of OCFAs by metabolic engineering in the oleaginous yeast, Yarrowia lipolytica.Y. lipolytica Wild-Type was shown able to grow on propionate and accumulate OCFAs. In order to improve the accumulation of OCFAs, the competitive pathway (PHD1 in methylcitrate pathway) was inhibited resulting in an increase of OCFAs production from 28.3 % to 46.8 % in total lipids. Further engineering of lipid synthesis pathway by blocking triacylglycerol remobilization and β-oxidation (TGL4, MFE1) and by strengthening carbon flux to lipid synthesis (GPD1, DGA2) allowed the increase of OCFAs production reaching to 0.57 g/L. The pool of precursors of OCFAs (propionyl-CoA, acetyl-CoA, and -ketovaleryl-CoA) was boosted by introducing propionate activating enzyme (PCT) and acetate supplementation, thus, the OCFA production was significantly improved in titer and content in total lipids (0.99 g/L and 65.9%, respectively).As well as metabolic engineering approach to utilize propionate as a substrate, Y. lipolytica has been developed for the de novo production of OCFA without propionate supplementation. A modular metabolic pathway up-regulating threonine synthesis resulted in the increase of OCFA by 12 times in engineered strain compared to Wild-type strain (0.36 vs. 0.03 g/L). This result highlights the possibility of using low-cost substrate for the production of OCFAs in Y. lipolytica. In brief, the Y. lipolytica strain able to accumulate high level of OCFAs, mainly heptadecenoic acids (C17:1), has been successfully developed by metabolic engineering. This work paves the way for further improvements of the production of OCFAs and its derived compounds.