Assessing the microbial communities inhabiting drinking water networks and nitrifying enrichments with special respect on nitrifying microorganisms

This study provides a comprehensive microbiological survey of three drinking water networks applying different water treatment processes. Variability of microbial communities was assessed by cultivation-based [nitrifying, denitrifying most probable number (MPN) heterotrophic plate count] and sequence-aided terminal restriction fragment length polymorphism (T-RFLP) analysis. The effect of microbial community composition on nitrifying MPN values was revealed. The non-treated well water samples showed remarkable differences to their corresponding distribution systems regarding low plate count, nitrifying MPN, and the composition of microbial communities, which increased and changed, respectively, in distribution systems. Environmental factors, such as pH, total inorganic nitrogen content (ammonium and nitrite concentration), and chlorine dioxide treatment had effect on microbial community compositions. The revealed heterogeneous nitrifying population achieved remarkable nitrification, which occurred at low a...