FOF1-ATPase mediates regulation of fermentation and energy metabolism at pH 5.5

The activity of F_OF₁-ATP synthase (F_OF₁) is vital for the survival and anaerobic growth under acidic conditions providing efficient metabolism and energy for cellular function. This study demonstrated the role of F_OF₁-ATPase in the metabolic pathways and regulation of proton motive force in Escherichia coli at pH 5.5 during the fermentation of glucose, glycerol and formate. Alteration of the ratio of fermentation end-products was shown. The possible mechanisms for efficient energy utilization in cells lacking F_OF₁ were shown. It is suggested that Fdh-H transfers H⁺ from formate to Hyd, which serves not only for H₂ generation but also for H⁺ cycling to F_OF₁ or directly to F_OF₁ in cells grown for 20 h. The interaction between H₂ and H⁺ cycling was proposed as an essential mechanism for balancing ΔpH at acidic conditions. F_OF₁-ATPase was identified to play a pivotal role in forming both components of Δp at 20 h and 72 h.