Efficient nitrogen removal by a novel extreme strain, Pseudomonas reactans WL20-3 under dual stresses of low temperature and high alkalinity: Characterization, mechanism, and application

Although many studies report the resistance of heterotrophic nitrification-aerobic denitrification (HN-AD) strains to single environmental stress, there is no research on its resistance to dual stresses of low temperature and high alkalinity. A novel bacterium Pseudomonas reactants WL20-3 isolated in this study showed removal efficiencies of 100%, 100%, and 97.76% for ammonium, nitrate, and nitrite, respectively, at 4 degrees C and pH 11.0. Transcriptome analysis revealed that the resistance of strain WL20-3 to dual stresses was attributed not only to the regulation of genes in the nitrogen metabolic pathway, but also to genes in other pathways such as the ribosome, oxidative phosphorylation, amino acid metabolism, and ABC transporters. Additionally, WL20-3 removed 83.98% of ammonium from actual wastewater at 4 degrees C and pH 11.0. This study isolated a novel strain WL20-3 with superior nitrogen removal under dual stresses and provided a molecular understanding of its tolerance mechanism to low temperature and high alkalinity.