Simultaneous aerobic nitrogen and phosphate removal capability of novel salt-tolerant strain, Pseudomonas mendocina A4: Characterization, mechanism and application potential

Abstract

A salt-tolerant strain, Pseudomonas mendocina A4, was isolated from brackish-water ponds showing simultaneous heterotrophic nitrification-aerobic denitrification and phosphorus removal capability. The optimal conditions for nitrogen and phosphate removal of strain A4 were pH 7–8, carbon/nitrogen ratio 10, phosphorus/nitrogen ratio 0.2, temperature 30 °C, and salinity range of 0–5 % using sodium succinate as the carbon source. The nitrogen and phosphate removal efficiencies were 96–100 % and 88–96 % within 24 h, respectively. The nitrogen and phosphate removal processes were matched with the modified Gompertz model, and the underlying mechanisms were confirmed by the activities of key metabolic enzymes. Under 10 % salinity, the immobilization technology was employed to enhance the nitrogen and phosphate removal efficiencies of strain A4, achieving 87 % and 76 %, respectively. These findings highlight the potential application of strain A4 in both freshwater and marine culture wastewater treatment.