THE KINETICS OF THE CHEMIOSMOTIC PROTON CIRCUIT OF THE IRON-OXIDIZINGBACTERIUM THIOBACILLUS-FERROOXIDANS

The kinetics of the coupling of the redox reactions and oxidative phos phorylation in Thiobacillus ferrooxidans is analyzed by the methods of electrochemical kinetics. The chemiosmotic circuit operates in a mann er analogous to the circuit of a fuel cell or a battery: anodic and ca thodic reactions are connected in one half of the circuit by the elect ron-transport chain, and in the other half of the circuit by the solut ion and the adenosine triphosphate (ATP) synthase. It is shown that th is model predicts that the rate of oxidation of ferrous ions at low co ncentrations is half order in the concentration of ferrous ions, and a t high concentrations it is zero order. This electrochemical hypothesi s is supported by the experimental results, including both the bioener getic parameters and the measurement of the rate of bacterial growth. (C) 1997 Elsevier Science S.A.