FIG. 3.

Single optical slice through a section of an activated sludge floc (from Wanlip), showing Nso1225-labeled microcolonies of a range of diameters, most of which are of above average (see Fig. 4) for this plant. Bar, 10 μm. Although the cells are very close together, they will not all appear to touch, as even perfectly packed spheroids make contact with adjacent particles at only one point on any given side.