Table 1.

Summary of the synthetic FA or FA and CO₂ assimilation pathways

Pathway	Substrate(s)	Product	Required amount of ATP and reducing power a)	Description	Reference(s)
Formolase pathway	FA	Dihydroxyacetone phosphate	4 ATP and 3 NADH	Employs de novo enzyme (Fls) FA assimilation was only demonstrated in vitro	[ 39 ]
Synthetic acetyl‐CoA pathway	FA	Acetyl‐CoA	2 ATP and 2 NADH	Employs de novo enzyme (Gals) FA assimilation was demonstrated in vivo	[ 40 ]
Reconstructed THF cycle and reverse glycine cleavage pathway	FA and CO2	Pyruvate	2 ATP, 1 NADH, and 2 NADPH	THF cycle was reconstructed by employing heterologous enzymes	[ 29 , 30 , 31 ]
Modified serine cycle	FA and CO2	Acetyl‐CoA	3 ATP, 1 NADH, and 2 NADPH	Serine cycle was reconstructed by employing heterologous enzymes Consists longer metabolic pathway compared with other synthetic FA assimilation pathways	[ 47 ]
Synthetic homoserine cycle	FA	Acetyl‐CoA	1 ATP and 1 NADH	Less energy required compared with the modified serine cycle Shorter metabolic pathway compared with the modified serine cycle	[ 48 ]

^a)Total amount of ATP and reducing powers (NADH and NADPH) required to synthesize one molecule of product from FA or FA and CO₂.