Nitrogen removal by a novel strain Priestia aryabhattai KX-3 from East Antarctica under alkaline pH and low-temperature conditions

To boost the poor nitrogen removal capacity of microorganisms under alkaline and low-temperature conditions, a new strain Priestia aryabhattai KX-3 able to heterotrophically nitrify and aerobically denitrify (HN-AD) was isolated from the Larsemann Hills in East Antarctica. The unique HN-AD function described herein has never been reported previously. At 10 ℃ and pH 10.0, strain KX-3 can remove 96.0% of nitrate–N (40 mg/L), 92.5% of ammonium–N (40 mg/L), and 56.7% of nitrite–N (40 mg/L). In addition, functional genes (amoA, hao, napA, nirS, and nosZ) and three key enzymes related to nitrogen reduction (NIR, NR and HAO) were detected, confirming the HN-AD abilities of strain KX-3. Finally, transcriptomics data confirmed the up-regulation of genes associated with the GDH pathway, such as gln A and gltBD. In addition, the genes for the cold-resistant ABC transporters and Na⁺/H⁺ antiporters (MnhACDEFG, NhaCD, and TrkAH) were expressed highly. Strain KX-3 has a strong potential for nitrogen removal under low temperature and alkaline conditions. Moreover, it also provides reference value for research on microbial tolerance to extreme conditions in East Antarctica.