FIG. 1.

Schematic view of the diffusion-limited assay system used to expose cell suspensions of homoacetogens to controlled O₂ fluxes. The reservoir (a) contained H₂ and CO₂ (80:20, vol/vol). The gas interchange between the reservoir and the reaction compartment (b) was controlled by a Teflon membrane (c) held in place by an O-ring. Different fluxes of O₂ were achieved by adding defined amounts of O₂ to the reservoir. The reaction compartment contained the cell suspension and a magnetic stir bar (d); the sampling port was fitted with a butyl rubber stopper (e).