Novel heterotrophic nitrogen removal and assimilation characteristic of the newly isolated bacterium Pseudomonas stutzeri AD-1.

AD-1, an aerobic denitrifier, was isolated from activated sludge and identified as Pseudomonas stutzeri. AD-1 completely removed NO or NO and removed 99.5% of NH during individual culturing in a broth medium with an initial nitrogen concentration of approximately 50 mg L. Results showed that larger amounts of nitrogen were removed through assimilation by the bacteria. And when NH was used as the sole nitrogen source in the culture medium, neither NO nor NO was detected, thus indicating that AD-1 may not be a heterotrophic nitrifier. Only trace amount of NO was detected during the denitrification process. Single factor experiments indicated that the optimal culture conditions for AD-1 were: a carbon-nitrogen ratio (C/N) of 15, a temperature of 25°C and sodium succinate or glucose as a carbon source. In conclusion, due to the ability of AD-1 to utilize nitrogen of different forms with high efficiencies for its growth while producing only trace emissions of NO, the bacterium had outstanding potential to use in the bioremediation of high-nitrogen-containing wastewaters. Meanwhile, it may also be a proper candidate for biotreatment of high concentration organic wastewater.