Fig. 1

Exemplary height maps of biofilms that were cultivated using microfluidic continuous flow reactors with lactate as electron donor. Cultivation was carried out under oxic conditions and the retention time was 5.23 min at a flow rate of 4 mL h⁻¹. After 44, 69, 93, 117 and 142 h five images were taken of each cultivation channel, converted into color-coded height maps by processing and combined into one image by stitching. The cultivation channels shown have a size of 3 × 45 mm and correspond to a top view of the biofilm, with a flow direction from left to right. Cultivations were performed in triplicate. Note that after 117 h, only one flow cell of bpfA remained due to biofilm washout, and only one flow cell of bpfG remained at 117 h and none at 142 h. Remaining height maps are available in Figure S3 of the supplementary materials.