Identification and characterization of a bacterial strain C3 capable of aerobic denitrification

A bacterial strain C3 screened from the activated sludge was found capable of aerobic denitrification and the denitrifying capability of the strain was studied in batch culture under aerobic condition. The results showed that the nitrate in the culture could be efficiently removed by strain C3 and the nitrogen removal rate was up to above 90%. According to the morphological observation, physiological biochemical test and sequence analysis of the 16S rDNA, strain C3 was identified as Pseudomonas sp.. And the phylogentic position of the strain was performed based on the phylogenetic tree. The factors affecting aerobic denitrificatrion by strain C3 were also discussed. The results indicated that the most suitable temperature and pH value for aerobic denitrification were 30°C and 7.0, respectively. The denitrification performance of strain C3 was almost not affected by the presence of oxygen and the strain C3 had a higher tolerance of dissolved oxygen concentration than other aerobic denitrifiers reported previously. The optimal C/N ratio was 5.5-6.0 and nearly complete denitrification can be obtained at the range of C/N ratio.