Electrosynthesis Of High Value-added Chemicals From Acetate In Yarrowia Lipolytica

The synthesis of fatty alcohols and terpenes requires coordination of center carbon metabolism,ATP and the reducing cofactors.As lipid microorganism,Yarrowia lipolytica has the high acetyl-Co A flux,which is conducive to the synthesis and accumulation of fatty alcohols and triterpenoids.In the microbial electrosynthesis(MES)system,microorganisms transfer electrons from electrode into the cell through various EET pathways.This is beneficial to balance the redox state required for products synthesis and cell physiological metabolism.In this study,we first explored the effects of common factors(antibiotics,phosphate buffer and electron shuttle in the catholyte of microbial electrosynthesis system)on the growth and products accumulation of Yarrowia lipolytica.The microbial electrosynthesis system of Yarrowia lipolytica was successfully established.Next,we constructed a recombinant engineering strain YLFL-11 by optimizing fatty alcohols synthesis pathway genes,knocking out fatty alcohol metabolism pathway genes and introducing heterologous acetic acid metabolic pathway(ack A-pta pathway)to enhance the supply of acetyl-Co A precursor.Strain YLFL-11 can efficiently metabolize acetate to produce fatty alcohols.Under the condition of supplying of a small amount of glucose(5 g/L),applying-1 V(vs.Ag/Ag Cl)cathode potential,adding 0.1 m M NR and 0.2 M phosphate buffer solution to the cathode solution,strain YLFL-11 achieved high fatty alcohols production with 4.1% acetate as the substrate carbon source through the established microbial electrosynthesis system.The yield of fatty alcohols reached 83.8 mg/g DCW after 48 h,which was 1.24 times and 1.39 times that of shake flask fermentation(67.3 mg/g DCW)and electrosynthesis control(60.1 mg/g DCW),respectively.Finally,we introduced the heterologous ack A-pta pathway to construct strains YLLU-1 and YLBA-1 on the basis of the original strains that produced high triterpenoid.Strains YLLU-1 and YLBA-1 achieved high production of lupeol(13.58 mg/g DCW)and betulinic acid(3.74 mg/g DCW)under the same microbial electrosynthesis conditions.So far,we have successfully applied the microbial electrosynthesis system to synthesize fatty alcohols and triterpenoids in Yarrowia lipolytica.This study expands the types of microbial electrosynthesis products and provides a reference for the industrial application of the system.