Abstract:One strain of denitrifying bacteria named XP1 was isolated from the rhizosphere soils of Typha in constructed wetland of Nansi Lake. Some physiological properties of XP1 were investigated, such as denitrification capacibility, ecological affecting factor and growth curve. A certain of purifying strain of XP1 was inoculated to the rhizosphere soil of Typha to determine its enhancement effects on denitrification. That citrate sodium was the most suitable carbon source for XP1 to carry out denitrification, and the suitable range of pH value was 7.0~9.0(The optimal value was 8.0). The corresponding optimal C/N ratio and initial nitrogen concentration were 7 and 30mg/L respectively. XP1 could reach logarithmic phase by 8 h cultivation, and more than 90% of TN removal could be achieved. TN removal rate of Typha could be increased from 46% to 90% after adding purifying strain of XP1. By analyzing the forms of nitrogen of enhancement experiment, XP1 showed high TN removal performance and inclined to utilize nitrite to achieve denitrification. Additionally, according to the morphology observation, the strain of XP1 belonged to Grame-negative bacillic, and the length of single cell was about (0.25~0.3)′(0.6~0.8)mm. Based on the detection of 16S rDNA sequence, phylegenetic tree was constructed. The final analysis results of gene sequence identified XP1 as Paenibacillus sp.