Characterization of Bacillus subtilis Ab03 for efficient ammonia nitrogen removal

An efficient ammonia nitrogen degrading bacterial strain was isolated from a fish and shrimp pond and identified as Bacillus subtilis (Ab03). Firstly, the strain was continuously domesticated in ammonium solution to improve its nitrogen removal capacity. The performance of the strain in terms of nitrogen removal efficiency under different culture conditions was then examined. Finally, the nitrogen removal process and related strain mechanisms were analyzed by nitrogen balance. The results showed the strain Ab03 could remove 91.67% of NH4+-N at 300 mg/L under the conditions of glucose as the single carbon source, C/N of 15, pH of 7.5, the temperature of 35 ℃ and dissolved oxygen of 7–8 mg/L. It was also found that under conditions where ammonia nitrogen was the only nitrogen source, strain Ab03 could also undergo aerobic denitrification for simultaneous conversion, with a final gas conversion rate of 74.81%.