Enhanced limonene production by optimizing the expression of limonene biosynthesis and MEP pathway genes in E. coli

Bioresources and Bioprocessing

Table 4 The terpenoid production increased in this study and previous studies

Products	Production increased	Genes overexpressed	References
Isoprene	0.4-fold	dxs and dxr^a	Xue et al. [16]
Phytoene	2.1-fold	idi	Kajiwara et al. [36]
Isoprene	2.3-fold	dxs and dxr	Zhao et al. [17]
β-Carotene	2.7-fold	idi	Kajiwara et al. [36]
Abietadiene	2.8-fold	dxs, dxr and idi	Morrone et al. [33]
Squalene	2.9-fold	dxs and idi	Ghimire et al. [37]
Limonene	3.4-fold	*dxs* and *idi*	This work
Carotenoids	3.5-fold	dxs, dxr and idi	Albrecht et al. [38]
Isoprene	4.0-fold	dxs, ispG^b, ispH^c, idi, ispE^d, dxr, ispD^e and ispF^f	Zurbriggen et al. [18]
Lycopene	4.5-fold	idi	Kajiwara et al. [36]
Isoprene	4.8-fold	dxs, dxr and idi	Lv et al. [19]
Taxadiene	15.6-fold	dxs, idi ispD and ispF	Ajikumar et al. [14]
Levopimaradiene	611.3-fold	dxs, idi ispD and ispF	Leonard et al. [15]

The rate-limiting enzymes in the MEP pathway were overexpressed in all the studies listed in this table.
^aThe gene of 1-deoxy-d-xylulose-5-phosphate reductoisomerase;
^bThe gene of (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate synthase;
^cThe gene of (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate reductase;
^dThe gene of 4-diphosphocytidyl-2-c-methyl-d-erythritol kinase;
^eThe gene of 2-c-methyl-d-erythrtol-4-phosphate cytidyltransferase;
^fThe gene of 2-c-methyl-d-erythritol 2, 4-cyclodiphosphate synthase.