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

Certainmetal ions can contribute to the functional microorganisms becoming dominant by stimulating their metabolismand 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 themechanismof Fe3+ ion stimulation of aerobic denitrification, benefiting the practicable application of aerobic denitrifiers. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Certain metal ions can enhance the metabolic activity and nitrogen assimilation capacity of denitrifying bacteria, while also reducing decay rate and increasing nitrate reduction rate through upregulating napA gene transcription and nitrate reductase activity. This study provides a theoretical foundation for understanding the mechanism of metal ion stimulation in aerobic denitrification, which could benefit the practical application of denitrifiers.