Fig. 6: Decoupling the synthesis and degradation of TAG to improve the production of PUFAs and their derivatives.

a Diagram of PUFA production in wild-type strains when glucose was used as the initial substrate (Strategy 1). b Diagram of PUFA production in the engineered strain after blocking lipid degradation-related genes with glucose as the initial substrate (Strategy 2). Blocking the TGL4 and PEX10 genes is represented by red double slash, and TAG degradation process blocking is represented by a red funnel. c Diagram of PUFA production in the engineered strain with the decoupling of TAG synthesis and degradation using glucose as the initial substrate. The TGL4 gene and the dCas9-VPR expression cassette are both controlled by the P_EYK promoter. The black dotted line represents the decoupling time point of TAG synthesis and degradation. In stage I of fermentation, the TGL4 gene is not expressed in the absence of erythritol (red light). In stage II of fermentation, the TGL4 and dCas9 genes are activated and expressed in the presence of erythritol (green light) (Strategy 3). Erythritol is represented by the blue ball. VPR, hybrid tripartite transcriptional activator VP64-p65-Rta. d C20:5 and lipid titers of YIP56 and the engineered strains YIP56-D2 and YIP56-D3. The black dotted line represents the decoupling time point of TAG synthesis and degradation. e Biosynthesis pathway of C22:5 and PGF2α. Elo5, Δ-5 elongase; COX, cyclooxygenase; PGF, prostaglandin F synthase. f C22:5 titers of the engineered strains YIP58 and YIP58-D3. The green arrow represents the time point of inducer addition. g PGF2α titers of the engineered strains YIP60 and YIP60-D3. The blue arrow represents the time point of inducer addition. In (d, f–g), data are presented as the means ± s.d. from three (n = 3) biologically independent replicates.