Conversion behavior of heterotrophic nitrification - aerobic denitrification bacterium Paracoccus denitrificans HY-1 in nitrogen and phosphorus removal

The heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria harbored remarkable removal capacity in eliminating single nitrogen pollutant, but their comprehensive performance in dealing with mixed nitrogen sources remained unknown. In this study, the denitrification capacity of HN-AD bacteria Paracoccus denitrificans HY-1 was explored through whole-genome sequencing and nitrogen metabolic pathway analysis, and the complex nitrogen sources with gradient concentration were used to validate its nitrogen removal efficiency under both aerobic and anaerobic conditions. The results demonstrated that strain HY-1 harbored an efficient degradation capacity on three nitrogen sources, and the removal rates of NH4+-N, NO2−-N and NO3−-N were 10.67 mg·L−1·h−1, 27.81 mg·L−1·h−1, and 22.05 mg·L−1·h−1, respectively. The denitrification rate of 15.33 mg·L−1·h−1 was obtained under anaerobic condition with mixed nitrogen sources. Also, the simultaneous nitrification denitrification phosphorus removal (SNDPR) trial revealed that strain HY-1 could eliminate PO43−-P with a rate of 0.38 mg·L−1·h−1 under coexistence condition of the three nitrogen sources. Combined with the nitrogen balance analysis, the results indicated that strain HY-1 possesses a great potential for application in complex nitrogen and phosphorus contaminated environments.