Keywords: 3HP/4HB; 3-hydroxypropionate/4-hydroxybutyrate cycle; ACC; acetyl-CoA/propionyl-CoA carboxylase; MCR; malonyl-CoA/succinyl-CoA reductase; MSR; Malonic semialdehyde reductase; HPCS; 3-hydroxypropionyl-CoA synthetase; HBCS; 4-hydroxybutyryl-CoA synthetase;