Figure 10From: Co-cultivation of Lactobacillus zeae and Veillonella criceti for the production of propionic acid Simplified scheme of propionate metabolism in Veillonella spec.: In contrast to Propionibacterium spec., in Veillonella spec. there is no transcarboxylase . The transcarboxylation is realized via a pyruvate-carboxylase and a methyl-malonyl-CoA-decarboxylase. This is less energy efficient. 1 mol ATP is consumed by the pyruvate-carboxylation, two third can be recovered by the fumarat-reduction, one third via methylmalonyl-CoA-decarboxylation. As in the acryloyl-pathway there is no net ATP production. The regeneration of NADH2 to NAD can be realized by hydrogen production, which is more energy efficient (Denger and Schink (1992)).Back to article page