FIG. 2.

In situ identification of nitrifying bacteria in activated sludge from the Kraftisried plant. (A) Simultaneous in situ hybridization with Cy3-labeled probe NmV and FLUOS-labeled probe NEU. N. mobilis cells appear yellow because of the overlapping labels. For visualization of the activated sludge floc, its autofluorescence was recorded with a 633-nm laser and colored blue by image analysis. (B) Simultaneous in situ identification of N. mobilis and Nitrospira-like bacteria after in situ hybridization with FLUOS-labeled probe NmV (green) and Cy3-labeled probe S-*-Ntspa-1026-a-A-18 (red). A phase-contrast image was superimposed for visualization of the floc material.