Increasing medium chain fatty acids production in Yarrowia lipolytica by metabolic engineering

Coraline Rigouin,Alain Marty,Maher Ben Khaled,Thierry Chardot,Vinciane Borsenberger,Florence Bordes,Christian Croux

doi:10.1186/s12934-018-0989-5

Abstract

BackgroundOleaginous yeast Yarrowia lipolytica is an organism of choice for the development of biofuel and oleochemicals. It has become a chassis for metabolic engineering in order to produce targeted lipids. Understanding the function of key-enzymes involved in lipid metabolism is essential to design better routes for enhanced lipid production and for strains producing lipids of interest. Because medium chain fatty acids (MCFA) are valuable compounds for biokerosene production, we previously generated strains capable of producing MCFA up to 12% of total lipid content (Rigouin et al. in ACS Synth Biol 6:1870–1879, 2017). In order to improve accumulation and content of C14 fatty acid (FA), the elongation, degradation and accumulation of these MCFA in Yarrowia lipolytica were studied.ResultsWe brought evidence of the role of YALI0F0654 (YlELO1) protein in the elongation of exogenous or de novo synthesized C14 FA into C16 FA and C18 FA. YlELO1 deletion into a αFAS_I1220W expressing strain leads to the sole production of C14 FA. However, because this strain does not provide the FA essential for its growth, it requires being cultivated with essential fatty acids and C14 FA yield is limited. To promote MCFA accumulation in Y. lipolytica without compromising the growth, we overexpressed a plant diglyceride acyltransferase specific for MCFA and reached an accumulation of MCFA up to 45% of total lipid content.ConclusionWe characterized the role of YlELO1 in Y. lipolytica by proving its involvement in Medium chain fatty acids elongation. We showed that MCFA content can be increased in Yarrowia lipolytica by promoting their accumulation into a stable storage form (triacylglycerides) to limit their elongation and their degradation.

Highlights

Oleaginous yeast Yarrowia lipolytica is an organism of choice for the development of biofuel and oleochemicals
The protein is composed of two subunits: αFAS consists of the acyl carrier protein (ACP), ketoacyl reductase (KR), ketoacyl synthase (KS) and phospho panthetheine transferase (PPT) domains, and βFAS consists of the acyl transferase (AT), enoyl reductase (ER), dehydratase (DH) and malonyl palmitoyl transferase (MPT) domains
Identification of elongase sequences in Y. lipolytica proteome In S. cerevisiae, three ELO proteins were identified: ELO1 protein is involved in vivo, in the elongation of myristic acid (C14 fatty acid (FA)) to palmitic acid (C16 FA) [32, 33] whereas ELO2 and ELO3 are involved in synthesis of Very long chain fatty acids (VLCFA) (C16/C18 to C26 FA), substrates for sphingolipids synthesis [24, 25]

Summary

Introduction

Oleaginous yeast Yarrowia lipolytica is an organism of choice for the development of biofuel and oleochemicals It has become a chassis for metabolic engineering in order to produce targeted lipids. Microbial oils are promising alternatives to fossil fuels [1] In this context, there is a growing interest in microbe engineering to produce valuable fatty acids to be used as biofuel or oleochemicals [2,3,4]. In Saccharomyces cerevisiae, the VLCFA are incorporated into ceramide and serve as components of sphingolipids [25] and glycosylphosphatidylinositol-anchor lipid fractions [26] They play an essential role in the cells as the deletion of one of the gene involved in their synthesis is associated with pleiotropic deficiencies

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