Research On The Synthesis Of Odd-chain Fatty Acids By ?-alanine Pathway In Saccharomyces Cerevisiae

Odd-chain fatty acids and their derivatives have attracted more attention due to their unique pharmacological properties and application prospects in chemical raw materials and advanced fuels.However,the majority of fatty acids are even-chains,and the odd-chain fatty acids are few.In this study,we constracted the ?-alanine pathway for synthesize odd-chain fatty acids from glucose in Saccharomyces cerevisiae using intermediates such as 3hydroxypropionic acid(3-HP)and malonic acid.Firstly,the feasibility of oddchain fatty acid biosynthesis from 3-HP was confirmed by introducing 3hydroxypropionyl-CoA dehydratase from Sulfolobus tokodaii(3Hpcd),3hydroxypropionyl-CoA synthase(3Hpcs)and acryloyl-CoA reductase(Acr)from Metallosphaera sedula.Then,the production ability of 3-HP was enhanced through the ?-alanine pathway by heterogeneous expression of genes TcPAND,BcBAPAT,ydfG as well as a downregulation of endogenous PYK1 gene,and the final titer of 3-HP reached 732 mg/L.Finally,the proportion of odd-chain fatty acids synthesized by the recombinant cells using glucose increased from 1.4%to 20.3%,and the accumulation of odd-chain fatty acids reached the highest of 74.8 mg/L,and the yield increased by about 21-folds.Among them,heptadecenoic acid(C17:1)and heptadecanoic acid(C17:0)accounted for 12.1%and 7.6%of the total lipid content,respectively.This study provides a new approach and research idea for de novo synthesis of odd-chain fatty acids.