Nitrogen removal performance, quantitative detection and potential application of a novel aerobic denitrifying strain, Pseudomonas sp. GZWN4 isolated from aquaculture water.

A novel Pseudomonas sp. GZWN4 with the aerobic nitrogen removal ability was isolated from aquaculture water, whose removal efficiency of NO-N, NO-N and NH-N was 99.72%, 82.54% and 98.62%, respectively. The key genes involved in nitrogen removal, nxr, napA, narI, nirS, norB and nosZ, were successfully amplified and by combination with the results of nitrogen balance analysis, it was inferred that the denitrification pathway of strain GZWN4 was NO-N → NO-N → NO → NO → N. The strain GZWN4 had excellent nitrite removal performance at pH 7.0-8.5, temperature 25-30 ℃, C/N ratio 5-20, salinity 8-32‰ and dissolved oxygen concentration 2.52-5.73 mg L. The receivable linear correlation (R = 0.9809) was obtained with the range of quantification between l0 and 10 CFU mL of the strain by enzyme-linked immunosorbent assay. Strain GZWN4 could maintain high abundance in the actual water and wastewater of mariculture and the removal efficiency of TN were 52.57% and 63.64%, respectively. The safety evaluation experiment showed that the strain GZWN4 had no hemolysis and high biosecurity toward shrimp Litopenaeus vannamei. The excellent nitrogen removal ability and adaptability to aquaculture environment made strain GZWN4 a promising candidate for treatment of water and wastewater in aquaculture.