Abstract：Dissimilatory Fe(III) and Mn(IV) oxide reduction by microorganisms has an important influence on the geochemistry and fate of organic or metal contaminants in environments. To explore the kinetic characteristics of the microbial reduction of Fe(III) and Mn(IV) oxide is the key to understand the mechanism of the interaction of “microbial-oxide-contaminants”. The current study mainly discussed the influence of anthraquinone-2-sulfonate (AQS), the concentration of the electron donor and goethite on the reduction of goethite by S12. The results showed the electron shuttle, AQS, could enhance the degree of goethite reduction. After 38 days incubation, the dissolved Fe(II) concentration was as much as 3.94 times of that in the non-AQS addition cell-goethite reaction system. The Michaelis-Menten kinetic model fit calculations showed the significant correlation between the initial reduction rate and the substrate concentration with a correlation coefficient, R2, high enough to 0.998. The electron shuttle, AQS, could have considerable influence on Vmax and Km values. The more reduction rate raised, the more energy(DE) will be more needed to drive ATP synthesis. When the microbial redox reaction almost kept in balance, the DG values reached the maximum.
