Figure 1: Final CO levels of the hydrogenogenic CO metabolism of C. hydrogenoformans was studied batch cultures, with CO2 trap and without CO2 trap (open versus closed symbols, resp.), in triplicate. Optical density of cultures ((a), square symbols), and partial pressures of CO ((b), triangles), H2 (diamonds), and CO2 (circles) were monitored over time and plotted on a linear axis. Trace levels of CO (c) were plotted on a logarithmic axis from 15.5 h onward.