In order to study the microbial community structure and diversity as well as the performance of phosphorus removal associated with microbial community change

the fingerprint profile technique of PCR amplified 16S rRNA and denaturing gradient gel electrophoresis (DGGE）were applied to analyse the microbial communities in Bi-Bio-Selective simultaneous Phosphorus and Nitrogen removal (BBSPN）process.After the characteristic bands eluted from gel were further recovered

cloned (reamplified）and sequenced

the sequences were compared with those in GenBank database and used for homology analysis

and the phylogenetic trees were constructed.The sequence of DGGE bands obtained showed that there is a good dynamic correlation between microbial community variation and its removal performance of process.TP removal efficiency of BBSPN process was lower when α-proteobacteria was the dominant species

which mean α-proteobacteria was not favorable for enhanced biological phosphorus removal; whereas when Bacteroidetes was the dominant species

TP removal efficiency and denitrifying dephosphorization were better and stable

which should attribute to Uncultured Sphingobacteriaceae.So

the Uncultured Sphingobacteriaceae was like to be one of the denitrifying phosphate accumulating organisms(DPAOs）in this process.Moreover

Acinetobacter

TM7 and Uncultured Trichococcus are also beneficial for phosphorus and nitrogen removal of BBSNP process.