Characterization of a novel Pseudomonas mosselii 9-1 capable of nitrate reduction to ammonium, ammonium assimilation, and denitrification in aerobic conditions

Pseudomonas mosselii 9-1 was isolated from Litopenaeus vannamei aquaculture wastewater and effectively removed ammonium and nitrate, with 98 % of ammonium and 45 % of nitrate removed within 24 h. Moreover, P. mosselii 9-1 tolerated as high as 2500 mg/L of ammonium along with the elimination of approximately 588 mg/L of it within 24 h. KEGG analysis revealed that rather than nitrification, P. mosselii 9-1 removes ammonium via heterotrophic ammonium assimilation, the presence of nirBD and nirK genes implicated reduction to ammonium and aerobic denitrification reduction to gaseous nitrogen, as the pathways involved in NO2− removal. Additionally, P. mosselii 9-1 can transform organic nitrogen to NH3 through ammonification. Single-factor analyses revealed a C/N ratio of 18, a temperature of >20 °C, pH 6–9, and sodium succinate as a source of carbon, favored the removal of ammonium and nitrate. P. mosselii 9-1 may be a promising biotreatment agent for wastewater containing high ammonium levels.