Abstract: In order to establish the foundation of new biological nitrogen removal process, a strain of Aeromonas was isolated from the roots of wetland plants in Dianchi Lake and was named as RC-15.The key denitrifying enzyme genes of the strain were studied by polymerase chain reaction (PCR), and the denitrification ability of the strain under different environmental conditions (carbon source, temperature, rotation speed, initial pH and C/N ratio) was studied. The results showed that the denitrifying enzyme genes, napA and nirK were successfully amplified, showing the strain had aerobic denitrification ability in the presence of oxygen molecules. The single factor experiment showed that the strongest denitrification ability was observed with the carbon source of sodium acetate, temperature of 30 ℃, initial pH of 8.0, and the C/N ratio of 7. Under those conditions, the removal ratio of nitrate reached 95.57% and its corresponded removal rate was 14.62 mg/(L·h) during the initial 24 h. In addition, the strain could remove nitrogen with low temperature, weak acid environment and low C/N.The identified strain RC-15 in this study could provide a new bacterial source to enhance the denitrification of actual wastewater.

Key words: aerobic denitrification, Aeromonas, functional genes, environmental factors, denitrification characteristics