Isolation and Identification of an Efficient Aerobic Denitrifying Pseudomonas stutzeri Strain and Characterization of Its Nitrite Degradation

Nitrogen pollution in water bodies is becoming increasingly serious, and how to remove nitrogen from water bodies economically and effectively has become a research hotspot. Especially in recent years, with the gradual expansion of aquaculture in China, the content of nitrite and other nitrogen-containing substances in water bodies has been increasing, which inhibits the growth of farm animals and is one of the causes of eutrophication in water bodies. In this study, a strain of bacteria was isolated from the sludge of an aquaculture fishpond and identified as Pseudomonas stutzeri, which can efficiently degrade nitrite. After continuous domestication in nitrite mixed solution, the nitrite nitrogen reduction capacity of P. stutzeri was significantly improved. Univariate experiments aiming to optimize the degradation conditions indicate that the optimal culture conditions for strain F2 are: medium with a carbon source of sodium succinate; C/N of 18; pH of 8; culture temperature of 28 & DEG;C; and shaking speed of 210 rpm in the shaker. Under the optimal culture conditions, the NO2--N concentration of the culture solution was 300 mg/L, and the nitrite removal rate reached 98.67%. Meanwhile, the results of the nitrogen balance test showed that the strain converted 6.1% of the initial nitrogen into cellular organic nitrogen and 62.3% into gaseous nitrogen.