FIG. 2.

Na⁺ dependence of hydrogen-dependent caffeate reduction by A. woodii. (A) Cell suspensions of A. woodii (1.54 mg of protein/ml) grown on fructose plus caffeate were prepared and incubated under an atmosphere of hydrogen at 30°C in a shaking water bath in a buffer containing NaCl as indicated. After preincubation for 30 min, caffeate was added from a stock solution. At the time points indicated, samples were withdrawn and analyzed for caffeate as described in Materials and Methods. Panel B displays the caffeate reduction rates as a function of the external Na⁺ concentration.