Denitrification characteristics and potential application of a novel aerobic denitrifying bacterium, Pseudomonas plecoglossicida, isolated from the Exopalaemon carinicauda pond

The excessive accumulation of nitrogen during aquaculture can cause water eutrophication, leading to serious environmental problems. Biological denitrification is an effective solution. The strain JW1, with high aerobic denitrification activity and high homology with Pseudomonas plecoglossicida, was isolated from the Exopalaemon carinicauda pond. Further study of strain JW1 revealed that it was Gram-negative and rod-shaped. The optimal conditions for growth and nitrogen removal were a C/N ratio of 10, a temperature of 28 degree celsius, a shaking speed of 150 rpm, and a salinity of 7.5. With NH4Cl or KNO3 as the sole nitrogen source, the removal rates of NH4+-N or NO3--N were 97.8% or 97.9%, respectively; with NH4Cl and KNO3 as mixed nitrogen sources, the removal rates of NH4+-N and NO3--N were 98.8% and 98.9%, respectively; and the accumulations of NO2--N were trace in all treatments. Strain JW1 had no hemolytic activity and was sensitive to most antibiotics. After 28 days of E. carinicauda application, the cumulative mortality (28.9%) and nitrogen concentration (1.24 mg/L of NO3--N, 0.49 mg/L of NO2--N, and 0.15 mg/L of NH4+-N) in the JW1 group significantly were lower than those in the control group (P < 0.05). The results revealed that strain JW1 was a high-performance and biosafe aerobic denitrifying bacterium, and provided a foundation for the healthy farming of shrimp.