FIG. 1.

(A) AFGAS setup for biofilm experiments. AFGAS was designed to perform a triplicate experiment. Gas sampling bags enclose both ends and isolate the flow system from the external atmosphere. Three flow lanes are independently connected to the waste bottle in order to avoid mixture of waste between lanes and to allow for effluent sampling from individual lanes. (B) Cross-section of the multilayer tubing. Tygon R-3063 tubing is reinforced with stainless steel pipes and epoxy resin. In order to maintain flexibility, the pump connections and the joints are composed of only a monolayer of Tygon R-3063 tubing. (C) Cross-section of the oxygen probe flow cell. A dissolved oxygen probe is contained in a flow cell made of butyl rubber. The butyl rubber flow cells are equipped with an inlet and an outlet. For dissolved oxygen measurements, the standard flow cell was replaced with the oxygen probe flow cell. (D) Sectioned diagram of a gas collector. The duplicated pump connections, upstream of the inlet and downstream of the outlet, prevent free spillage of gas from the gas collector and help to maintain a constant minimum volume of effluent in the gas collector.