TABLE 1.

Comparison of synthetic CO₂ fixation pathways with natural ones.

Pathway	Status	Fixed CO2 or HCO${}_3^{-}$	Product	ATP consumption	NAD(P)H consumption	CO2 capturing enzyme	Specific activity μ mol/min/mg	References
CBB	Natural	3	Glyceraldehyde-3-phosphate	9	6	Ribulose-1,5-bisphosphate, Carboxylase/oxygenase	3.5	Bar-Even et al., 2010
3HP bicycle	Natural	3	Pyruvate	7	5	Acetyl-CoA carboxylase, propionyl-CoA carboxylase	18, 30	Herter et al., 2001; Bar-Even et al., 2010
3HP/4HB cycle	Natural	2	Acetyl-CoA	6	4	Acetyl-CoA carboxylase, propionyl-CoA carboxylase	18, 30	Berg et al., 2007; Bar-Even et al., 2010
rTCA	Natural	2	Pyruvate	2	5	2-oxoglutarate synthase, isocitrate dehydrogenase	–, 53	Kim et al., 1992; Martinez et al., 2007
Wood-Ljungdahl	Natural	2	Acetyl-CoA	1	4	NAD-independent formate dehydrogenase, CO dehydrogenase/acetyl-CoA synthase	2.34, 0.46	Ragsdale, 1997
DC/HB cycle	Natural	2	Acetyl-CoA	5	4	Pyruvate synthase, PEP carboxylase	−, 35	Huber et al., 2008; Garcia-Gonzalez and De Wever, 2017
CETCH	Synthetic	2	Glyoxylate	1	4	CoA-dependent carboxylase
rGly	Synthetic	3	Pyruvate	2	3	Glycine cleavage system
Formolase path	Synthetic	3	Dihydroxyacetone phosphate	4	3	NAD-independent formate dehydrogenase
Partial formolase path + SACA path	Synthetic	2	Acetyl-CoA	2	2	NAD-independent formate dehydrogenase
partial formolase path + MCC path	Synthetic	1	Acetyl-CoA	1	1	NAD-independent formate dehydrogenase
CBB + MCG path	Natural + synthetic	2	Acetyl-CoA	5.5	4	PEP carboxylase, ribulose-1,5-bisphosphate, carboxylase/oxygenase