Lactate conversion to acetate,CO2 and H2 in cell suspensions of Desulfovibrio vulgaris (Marburg): indications for the involvement of an energy driven reaction

Cell suspensions of Desulfovibrio vulgaris were found to catalyze, in the absence of sulfate, the complete conversion of 1 lactate to 1 acetate, 1 CO₂, and 2 H₂ (G₀=-8.8 kJ/mol) and of 1 pyruvate to 1 acetate, 1 CO₂, and 1 H₂ (G₀=-52 kJ/mol). Protonophores, the proton translocating ATPase inhibitor N,N-dicyclohexylcarbodiimide, and arsenate specifically inhibited H₂ formation from lactate but not from pyruvate. The results suggest that lactate oxidation to pyruvate and H₂ (G ₀=+43.2 kJ/mol) is energy driven.     

Depolarization of the cell membrane causes inhibition of cell locomotion and pinocytosis inAcanthamoeba castellanii andAmoeba proteus

Summary 10 M CCCP protonophore in an acidic medium causes depolarization of the cell membrane and immediate cessation of locomotion inAcanthamoeba castellanii andAmoeba proteus. In the basic media there is no depolarization or inhibition of cell locomotion. Other depolarizing agents (alkali cations, crown molecules) also stop locomotion and induce pinocytosis in amoeba. Pinocytotic uptake of horseradish peroxidase byAcanthamoeba castellanii is increased by 69% in the presence of CCCP in the medium at pH 5.7 but is not influenced at higher pH values. This might indicate that both amoeboid locomotion and pinocytosis are controlled by membrane potential.