Advanced metabolic Engineering strategies for the sustainable production of free fatty acids and their derivatives using yeast

Abstract

The biological production of lipids presents a sustainable method for generating fuels and chemicals. Recognized as safe and enhanced by advanced synthetic biology and metabolic engineering tools, yeasts are becoming versatile hosts for industrial applications. However, lipids accumulate predominantly as triacylglycerides in yeasts, which are suboptimal for industrial uses. Thus, there have been efforts to directly produce free fatty acids and their derivatives in yeast, such as fatty alcohols, fatty aldehydes, and fatty acid ethyl esters. This review offers a comprehensive overview of yeast metabolic engineering strategies to produce free fatty acids and their derivatives. This study also explores current challenges and future perspectives for sustainable industrial lipid production, particularly focusing on engineering strategies that enable yeast to utilize alternative carbon sources such as CO₂, methanol, and acetate, moving beyond traditional sugars. This review will guide further advancements in employing yeasts for environmentally friendly and economically viable lipid production technologies.

Keywords: Carbon sources; Free fatty acid; Metabolic engineering; Yeast.

Fig. 1

A schematic overview of metabolic engineering strategies for producing FFAs in yeasts. Glucose, methanol, CO_2, and its derivative formate represent the initial carbon source. Overexpressed genes and knocked-out genes are shown in blue and red, respectively. Abbreviations: ACC1, acetyl-CoA carboxylase; ACL, ATP: citrate lyase; ACS, acetyl-CoA synthetase; ARE, sterol acyltransferases; CBB cycle, Calvin-Benson-Bassham cycle; CTP, citrate transporter; DAG, diacylglycerol; DAS, dihydroxyacetone synthase; DGA, diacylglycerol acyltransferases; DHA, dihydroxyacetone; FAA/FAT, fatty acyl-CoA synthetases; FAS, fatty acid synthetases; FDH, formate dehydrogenase; G3P, glyceraldehyde 3-phosphate; GapN, glyceraldehyde-3-phosphate dehydrogenase; GPD, glycerol-3-phosphates; LRO, diacylglycerol acyltransferase; MDH, malate dehydrogenase; ME, malic enzyme; MFE, multifunctional enzymes; 3PG, 3-phospho-glycerate; PAH/LPP/DPP/APP, phosphatidate phosphatases; PDH, pyruvate dehydrogenase; PEX10, peroxisome synthetase; PL, phospholipid; POX, peroxisomal acyl-CoA oxidase; PRK, phosphoribulokinase; PXA, peroxisomal acyl-CoA transporter; Pyr, pyruvate; SE, sterol esters; RuBisCO, ribulose 1,5-bisphosphate carboxylase/oxygenase; RuBP, ribulose 1,5-bisphosphate; TAG, triacylglycerol; TE/ACOT5/RnTEII/‘TesA, thioesterases; TGL, triacylglycerol lipases; Xu5P, xylulose 5-phosphate; XuMP cycle, xylulose monophosphate cycle

Fig. 2

A schematic overview of metabolic engineering strategies for producing FA, FAEE, and FALK in yeasts. Overexpressed genes and knocked-out genes are shown in blue and red, respectively. Abbreviations: ADC, aldehyde decarbonylase; ADH, alcohol dehydrogenases; ADO, aldehyde deformylating oxygenase; ALR, aldehyde reductases; BsuSfp, phosphopantetheinyl transferase; CAR, carboxylic acid reductase; CvFAP, fatty acid photodecarboxylase; DGAT, acyl-CoA-diacylglycerol acyltransferase; FAD, fatty aldehyde decarbonylase; FAR/TaFAR, fatty acyl-CoA reductases; HFD1, aldehyde dehydrogenase; PDC, pyruvate decarboxylase; SAAT, alcohol acyltransferase; WS, wax ester synthase; αDOX, α-dioxygenase