Fig. 4: Balancing acetyl-CoA distribution between lipid and isoprenoid synthesis benefits carotenoid accumulation.

a Cytosolic acetyl-CoA is shared between two competing pathways, de novo lipid biosynthesis and the MVA pathway. However, lipid bodies within the cell form a hydrophobic region in which carotenoids can be sequestered, thus promoting their accumulation. Consequently, both pathways are necessary, and an optimal partitioning of flux is crucial in achieving high carotenoid titers and per-cell content. In addition, intracellular TAGs can be used as a carbon source for acetyl-CoA generation, which in turn provides the building blocks for carotenoids. TAGs triacylglycerol, FFAs free fatty acids, IPP isopentenyl diphosphate, DMAPP dimethylallyl diphosphate. b Lipid content is dependent on the C/N ratio of the media, and a higher C/N ratio promotes lipid production. c, d β-carotene titer (c) and content (d) are also functions of the media C/N ratio. However, unlike lipid content, which increased monotonically with the C/N ratio, there is an optimum for β-carotene production. The highest titer and per-cell content of β-carotene occurred at a C/N ratio of 9:1 in Y₁₀P₁₀D₅₀ media. For b to d, The average and s.d. of three biologically independent experiments are shown. Source data are provided as a Source Data file.