Isolation And Identification Of The Dominant Strain Of Denitrification And Phosphorus Removal Bacterias In Granular Sludge

Water shortages and pollution has already become serious threat to human survival and development, in which the nitrogen and phosphorus are the main inducing factors. A class of microbe, known collectively as the denitrifying phosphorus removal bacteria (DPB), can execute denitrification and phosphorus removal at the same time, such microbe under anaerobic conditions, DPB can syntheze poly-β-hydroxybutyric acid (PHB) and release orthophosphate using organic comprounds under anaerobic condition, and it can denitrify by NOx-as electron acceptor using PHB as a carbon source and accumulate phosphorus. At present, DPBs include Stenotrophomonas sp., Acinetobacter sp., Pseudomonas sp., Moraxella sp., Aeromonas sp. and Enterobacter sp..This study aimed to identify the dominant species in denitrifying phosphorus removal activated sludge particles by DGGE analysis, purification culture, screening culture and physi-biochemistry methods. The results obtained are as follows:Analysis of bacterial populations in activated sludge. A total of12isolates were obtained from activated sludge, in which1isolate belonged to Thauera sp.,3isolates belonged to Thiothrix sp.,2isolates belonged to Acinetobacter sp. and6uncultured bacterial strain. Acinetobacter sp. had the function of denitrification and phosphorus removal, suggesting that it is the dominant species..Isolation and identification of dominant bacteria. A total of24bacteria strains were isolated in beef extract peptone medium culture, By culturing in three defective media, denitrification screening medium, phosphorus-deficient medium and phosphorus-rich medium, the strains DPB-F2and DPB-F5were identified as dominant strains. Further analysis with16S rDNA sequences PCR amplification and sequencing showed that both DPB-F2and DPB-F5belonged to Acinetobacter sp.. This result was confirmed by physiological and biochemical tests.