A novel hypothermic strain, Pseudomonas reactans WL20-3 with high nitrate removal from actual sewage, and its synergistic resistance mechanism for efficient nitrate removal at 4 °C

Nitrate can be well removed by bacteria at 25-30 & DEG;C. However, nitrate removal almost ceases at temperatures lower than 5 & DEG;C. In this study, a novel hypothermic strain, Pseudomonas reactans WL20-3 exhibited an excellent aerobic nitrate removal ability at 4 & DEG;C. It had high capability for the removal of nitrate, total dissolved nitrogen (TDN), and dissolved organic carbon (DOC) at 4 & DEG;C, achieving removal efficiencies of 100%, 87.91%, and 97.48%, respectively. The transcriptome analysis revealed all genes involved in the nitrate removal pathway were significantly up-regulated. Additionally, the up-regulation of ABC transporter genes and down-regulation of respiratory chain genes cooperated with the nitrate metabolism pathway to resist low-temperature stress. In actual sewage, inoculated with WL20-3, the nitrate removal efficiency was found to be 70.70%. Overall, these findings demonstrated the impressive capacity of the novel strain WL20-3 to remove nitrate and provided novel insights into the synergistic resistance mechanism of WL20-3 at low temperature.

Automated summary

In this study, a novel hypothermic strain Pseudomonas reactans WL20-3 was found to exhibit excellent aerobic nitrate removal ability at 4°C. It showed high capabilities for the removal of nitrate, total dissolved nitrogen (TDN), and dissolved organic carbon (DOC), achieving impressive removal efficiencies. Transcriptome analysis revealed gene up-regulation in the nitrate removal pathway, as well as the up-regulation of ABC transporter genes and down-regulation of respiratory chain genes, which contributed to the strain's resistance mechanism at low temperature. In actual sewage, the inoculated strain WL20-3 achieved a nitrate removal efficiency of 70.70%.