[Analysis on microbial community in biofilm coating onto solid carbon source using the PCR-DGGE technique]

Polylactic acid/Poly (3-Hydroxybutyrate-co-3-Hydroxyvalerate) (PLA/PHBV) granules were used as both carbon source and biofilm carrier for nitrate removal from the contaminated water. The polymerase chain reaction-denature gradient gel electrophoresis (PCR-DGGE) was used to investigate the dynamic change of microbial community in the biofilm coating onto PLA/PHBV granules. The results showed that a decrease in microbial diversity was observed at the initial stage of reactor operation. Shannon-Wiener and Simpson diversity indexes of microbial community in the biofilm slightly changed during the stable period of the reactor running. The major microorganisms in the biofilm were Gram-negative rod bacteria including the genera of Diaphorobacter, Acidovorax, Rubrivivax, Azospira, Thermomonas and Devosia, and all of them belonged to alpha-, beta- and gamma- Proteobacteria, according to the SEM photo of biofilm and 16S rDNA sequences of the DGGE profile. Moreover, the abundance of Diaphorobacter-like genera was the highest in the solid-phase-denitrification biofilm.