DYNAMICS OF A NITRIFYING BACTERIA POPULATION IN A BIOFILM CONTROLLED BY AN OXYGEN MICROELECTRODE

Population dynamics of nitrifying bacteria in an autotrophic biofilm w ere studied using an oxygen microelectrode. Nitrification and endogeno us respiration were measured as function of oxygen concentration. over a five weeks substrate-limiting period the shape of oxygen profiles i n the biofilm had changed. The activity in the biofilm showed that the autotrophic fraction was displaced to the bulk/biofilm interface. Aft er 5 weeks no more activity could be measured below 800 mu m in the su bstrate-limited biofilm. Full ammonia load couldn't be buffered by tho se biofilms. After setting back the biofilm to full load, the profiles reached the original shape after 5 days. The results of microelectrod e measurements were used to evaluate data for modelling population dyn amics of nitrifying bacteria.