On June 30, 2026, Junyang Wang and others from Beijing University of Chemical Technology published a research paper titled Engineering Rhodotorula toruloides as a platform organism for de novo synthesis of fatty-acid esters in Nature Communications.
This study uses the non-traditional oleo-producing yeast Rhodotorululoides as the foundation, and conducts modular metabolic engineering research on the de novo synthesis of three types of fatty acid esters—fatty acid ethyl esters (FAEEs), fatty acid short branched-chain esters (FASBEs), and wax esters (WEs)—without the addition of exogenous alcohols and lipid precursors: In FAEEs synthesis, the overexpression of the wax ester synthase AbWS and ethanol synthesis-related genes (RtPDC, BsADHII or AdhE mutant) only obtained a low titer of 29.0 mg/L, and due to insufficient intracellular ethanol supply, the study further constructed a combination of Saccharomyces cerevisiae and R. The aerobic/anaerobic dual-chamber co-culture system of toruloides uses Saccharomyces cerevisiae in situ to supply ethanol in a xylose-glucose carbon source, significantly increasing FAEEs shaker bottle output to 579 mg/L; In FASBE synthesis, keto acid decarbylase and alcohol dehydrogenase were introduced to synthesize isobutanol using amino acid precursors, but the cytoplasmic pathway yielded only 7.2 mg/L. An innovative mitochondrial regionalization strategy (ScGRX2m signaling peptide) was used to target downstream synthases on mitochondria to increase local substrate and enzyme concentrations, raising yield to 169 mg/L, and up to 698 mg/L with exogenous isobutanol supplementation; In WEs synthesis, lipid-CoA reductase (Maqu) and AbWS were introduced to construct a fatty alcohol pathway to achieve a baseline yield of 525 mg/L. Subsequently, plant-derived extensor CgKCS was introduced to synthesize jojoba-like extra-long chain wax esters (C38-C42), and co-expressed acetyl-CoA synthase ACS1 and ATP-citrate lyase ACL1 to enhance the supply of acetyl-CoA and precursors, raising the total wax ester in shake flasks to 1.30 g/L (including 278.29 mg/L for jojoba-like wax esters, accounting for 21.48%), and ultimately achieved a total wax ester of 13.04 g/L (jojoba-like 1.69 g/L), the highest reported titer in the current microbiology system, during batch fermentation of feed in the 5 L fermenter.
The innovations of this article are mainly reflected in the first-ever establishment of a universal platform in R. toruloides that can synthesize structurally diverse fatty acid esters de novo without exogenous alcohols or lipid precursors. It proposes and verifies two universal strategies—co-culture of alcohol-producing and lipid-producing microorganisms and organelle compartmentalization—to overcome the bottleneck of short-chain alcohol precursor supply. By combining chain length extension engineering with central metabolic precursor enhancement, it achieves the efficient synthesis of high-value-added jojoba-like wax esters and successfully completes fermenter scale-up. At the same time, it demonstrates that the chassis can be flexibly adapted to various wax ester synthases and utilize inexpensive carbon sources such as lignocellulose hydrolysate. This provides an efficient, economical, and environmentally friendly microbial manufacturing solution for the sustainable and low-cost industrial production of biodiesel, green surfactants, and cosmetic esters.