Biological stimulation with Fe(III) promotes the growth and aerobic denitrification of Pseudomonas stutzeri T13.

Abstract Certain metal ions can contribute to the functional microorganisms becoming dominant by stimulating their metabolism and activity. Therefore, Pseudomonas stutzeri T13 was used to investigate the impacts of biological stimulation with certain metal ions on aerobic denitrifying bacteria. Results showed that with the addition of 0.036 mmol/L Fe3+ ions, the nitrogen-assimilation capacity of P. stutzeri T13 significantly increased by 43.99% when utilizing ammonium as the sole nitrogen source. Kinetic models were applied to analyze the role of Fe3+ ions in the growth, and results indicated that increasing Fe3+ ion concentrations decreased the decay rate. The maximum nitrate reduction rate increased from 9.55 mg-N L-1 h-1 to 19.65 mg-N L-1 h-1 with Fe3+ ion concentrations increasing from 0.004 to 0.036 mmol/L, which was due to the increased level of napA gene transcription and activity of nitrate reductase. This study provides a theoretical foundation for further understanding of the mechanism of Fe3+ ion stimulation of aerobic denitrification, benefiting the practicable application of aerobic denitrifiers.