ENERGY-CONSERVATION BY SUCCINATE DECARBOXYLATION IN VEILLONELLA-PARVULA

Veillonella parvula cannot grow with succinate as sole energy source. However, succinate decarboxylation simultaneous with malate or lactate fermentation increased growth yields by 2.4-3.5 g (mol succinate)-1. Malate was fermented stoichiometrically to acetate and propionate whereas lactate fermentation produced more acetate and considerable amounts of H-2. Aspartate was utilized only in the presence of succinate as co-substrate. Methylmalonyl-CoA decarboxylase and ATP-dependent pyruvate carboxylase, but not methylmalonyl-CoA: pyruvate transcarboxylase, were detected in cell-free extracts of malate- or lactate-grown cells. The energetic aspects of these fermentation patterns are discussed.