Temporal dynamics of the microbial community in an integrated fixed-film activated sludge system revealed by 16S rRNA MiSeq sequencing

Illumina MiSeq high-throughput sequencing was used to reveal the temporal dynamic of microbial community structure and bacterial diversity in an integrated fixed-film activated sludge (IFAS) system over a seven-month period. Microbial community structure and bacterial diversity varied with different months in the system. The biofilm phase showed a more stable microbial community trait compared with the sludge phase with the fall in environmental temperature. Proteobacteria was the most predominant phylum in the IFAS system, followed by Bacteroidetes, Actinobacteria, Chloroflexi, Firmicutes, Planctomycetes and candidate division TM7. The most predominant ammonia oxidizing bacteria and nitrite oxidizing bacteria in the IFAS system were Nitrosomonas and Nitrospira, respectively. An evident shift in the abundance of nitrifying bacteria took place in the biofilm and sludge of the IFAS system during the sampling months. Principal coordinate analysis and a clustered heat map indicated that living conditions and temperature seemed to be the key factors in shaping the microbial community in the IFAS system.