Dynamics of Nitrobacteria Community in Biological Contact Oxidation Process by DGGE and FISH

The performance and nitrobacter population dynamics of a pilot-scale biological contact oxidation process which was used to purify a landscape river, were evaluated during the biofilm forming period over 45 days. Ammonia oxidizing bacteria (AOB) community structure and composition of nitrobacteria in the system were analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and fluorescence in situ hybridization (FISH) techniques. The results showed that 30% average removal efficiency of NH₄⁺-N and 15% average removal efficiency of chemical oxygen demanded (CODMn) were achieved. DGGE analysis represented a dynamic population with gradually evolved dominant species. The number of superior bands increased with the development of biofilm, and Data from 16S rRNA sequencing demonstrated genera Nitrosomonas was the dominant AOB in this system. FISH results suggested that AOB and nitrite-oxidizing bacteria (NOB) accounted for high up to 9.9% and 3.8% of the total bacteria, respectively, and Nitrospira was the dominant members of NOB in the biofilm. The general nitrobacteria population coupled with the performance of biological contact oxidation process indicated that the dynamics of the community structure of nitrobacteria was important indicator to evaluate the effect of the biofilter system.