... microprofiles of O 2 , NH 4 + , NO 2 - , and NO 3 - in the autotrophic nitrifying biofilm (B). The distribution and magnitude of the estimated specific rates of net consumption and production of ... of nitrifying bacterial populations and the in situ activity of these populations within the biofilms was discussed. Microsensors For analysis of microbial structure and function (activity) of ... biofilm. After reaching the steady-state condition, microprofiles of NH 4 + , NO 2 - , NO 3 - , and O 2 in the biofilms were measured by use of microsensors, and the spatial distributions of...