High-efficiency inorganic nitrogen removal by newly isolated Pannonibacter phragmitetus B1

An aerobic heterotrophic nitrogen removal bacterium strain, B1, was isolated from aquaculture water and identified as Pannonibacter phragmitetus (99% similarity) by 16S rRNA sequencing analysis. When ammonium, nitrite or nitrate was the sole nitrogen source, with an initial nitrogen concentration of 14 mg/L, the nitrogen removal efficiencies were 98.66%, 99.96% and 98.73%, respectively, and the corresponding maximum removal rates reached as high as 1.16, 0.77 and 0.81 mg/L/h, respectively. In the presence of NH₄⁺-N, the removal efficiency of 56 mg/L NO₂^--N within 27 h increased by 83.50%, and the corresponding removal rate reached as high as 1.72 mg/L/h. Additionally, different carbon sources (dl-malic acid, sucrose, sodium citrate, and glucose) could be utilized in nitrogen removal. Sequence amplification indicates that the denitrification genes nirK, norB and narG are present in strain B1. All results demonstrate that strain B1 has high promise for future applications of removing inorganic nitrogen from wastewater.