Simultaneous heterotrophic nitrification and aerobic denitrification by a novel isolated Pseudomonas mendocina X49

Six bacterial strains with simultaneous nitrification-denitrification abilities were isolated from a Beijing sewage treatment plant to improve nitrogen biodegradation efficiency. One of these strains, X49, was identified as Pseudomonas mendocina, and was characterized as the best strain with which to rapidly degrade a high concentration of inorganic nitrogen. X49 completely converted 5–100 mg.L−1 of ammonia in 12 h, with no nitrite accumulation; the maximum removal rate of 26.39 mg (N).L−1.h−1 was achieved between 4 h and 6 h. In 16 h, the strain removed 100 mg.L−1 nitrite and 72.61 mg.L−1 nitrate under aerobic conditions, at degredation rates which reached 4.54 and 6.25 mg (N).L−1.h−1, respectively. Our results suggest that P. mendocina X49 achieved efficient and simultaneous nitrification and denitrification ability under heterotrophic aerobic conditions.