FIG. 6.

Caffeate respiration with betaine as the reductant is impaired by CO₂. A. woodii was grown with betaine plus caffeate to preinduce the caffeate reduction machinery and harvested. Cell suspensions (1.0 mg protein/ml) were incubated in medium containing 50 mM betaine in the absence (squares) or presence (triangles) of 60 mM bicarbonate at 30°C in a shaking water bath. After preincubation for 10 min, 2 mM caffeate was added from a stock solution. At the times indicated, samples were withdrawn and analyzed to determine the caffeate (solid symbols) and acetate (open symbols) concentrations.