Engineered production of isoprene from the model green microalga Chlamydomonas reinhardtii

A synthetic biology and green bioprocess approach to recreate agarwood sesquiterpenoid mixtures

“…22,23 Enhanced heterologous terpenoid yields have been demonstrated from this green alga following metabolic engineering. 24–26 These include the knockdown of native squalene synthase ( Cr SQS-k.d.) which increased farnesyl pyrophosphate pools in the cytoplasm and led to improvements in heterologous bisabolene or patchoulol yields when their synthases were expressed.…”

“…which increased farnesyl pyrophosphate pools in the cytoplasm and led to improvements in heterologous bisabolene or patchoulol yields when their synthases were expressed. 24,26 Disruption of carotenoid homeostasis by introduction of a beta-carotene ketolase to biosynthesise ketocarotenoids in the plastid led to pronounced increases of heterologous isoprene biosynthesis 25 (Fig. 2a, right panel).…”

“…32 That algae rely on this pathway for essential photosynthetic carotenoids implies an inherent capacity to channel carbon fixed by photosynthesis to isoprenoids, which could be tapped for heterologous terpene biosynthesis. The first reports of micrograms of heterologous terpenes per litre of algal culture 27 have now been superseded by hundreds of milligrams per litre, 25,33 owing to improved transgene design, 34,35 enhanced metabolic channelling, and high-cell-density cultivation strategies. 26,36 Here, we demonstrate for the first time a combinatorial modification of two metabolic pathways simultaneously in C. reinhardtii by perturbing plastid carotenoid and cytoplasmic sterol biosynthesis in the same strain (Fig.…”

The synthetic future of algal genomes

“… 10 Another report demonstrated genetic engineering for the concomitant production of ketocarotenoids in algal biomass and volatile isoprene hydrocarbons in the culture headspace. 32 These examples illustrate the potential of engineered algae as light-driven, multi-product-generating cellular platforms for waste-stream revalorization.…”

“…reinhardtii has been genetically modified to produce heterologous isoprenoids, including patchoulol, 25 , 26 , 27 sclareol, 28 bisabolene, 29 casbene, 30 , 31 and volatile isoprene. 32 Middle: P . moriformis was engineered to make tailored triacylglycerol oils.…”