Table 1.

Representative examples of heterologously produced isoprenoids, along with hosts, supporting substrate provision pathways, product titers, and engineering steps that influenced subsequent studies or titer improvements^a

Compound	Heterologous host	Substrate provision pathway	Final titer(s) (intermediate or final compound)b	Step to enable or overproduce product	Reference
Paclitaxel	E. coli	MEP	1.3 mg/liter (taxadiene)	Overexpression of dxs and idi	26
			300 mg/liter (taxadiene), 58 mg/liter (taxadiene-5α-ol)	Overexpression and variation of copy number and promoter of dxs, idi, ispD, and ispF	2
	S. cerevisiae	MVA	1.0 mg/liter (taxadiene), 0.025 mg/liter (taxadiene-5α-ol)	None	15
			8.7 mg/liter (taxadiene)	Overexpression of a truncated HMG-CoA reductase; reduction of competing steroid pathway	16
Artemisinin	E. coli	MVA	155 mg/liter (amorphadiene; initial titer)	Introduction and overexpression of MVA pathway; foreign gene codon optimization; promoter variation; plasmid copy number variation; specific overexpression of mevalonate kinase	39
			1,084 mg/literc (amorphadiene; optimized titer)		4
			105 mg/liter (artemisinic acid)	Overexpression of MVA pathway; foreign gene codon optimization; promoter variation	10
	S. cerevisiae	MVA	0.6 mg/liter	None	38
			153 mg/liter (amorphadiene), 32 mg/liter (artemisinic acid)	Overexpression of a truncated HMG-CoA reductase; reduction of competing steroid pathway	52
Carotenoids	E. coli	MEP	6 mg/g DCW (β-carotene)	Overexpression of dxs, ispD, ispF, ispB, and idi	72
		MVA	22 mg/g DCW (lycopene)	Overexpression of mvaK1 (mvk), mvaK2 (pmk), mvaD (pmd), and idi	71
			12.5 mg/g DCW (lycopene)	Overexpression of MVA pathway with acetoacetyl-CoA ligase introduced	21
	S. cerevisiae	MVA	0.113 mg/g DCW (lycopene)	None	70
			5.9 mg/g DCW (β-carotene)	Overexpression of a truncated HMG-CoA reductase and endogenous geranylgeranyl diphosphate synthase	64

^aExamples are not comprehensive.

^bDCW, dry cell weight.

^cEstimated based upon an optical density at 600 nm (OD₆₀₀) of 3.7 (39); the actual value reported is 293 mg/liter/unit of OD₆₀₀.