[Isolation and characterization of the salt-tolerant aerobic denitrifying bacterial strain A-13].

OBJECTIVE: This study is aimed to isolate and identify an aerobic denitrifying bacterium with high ability for nitrogen removing, and optimize its growing and denitrifying conditions to obtain the theory basis for controlling the eutrophic artificial lake. METHODS: Aerobic denitrifying bacterium strain A-13 was screened by denitrifying medium. Strain identification was carried out through morphological, biochemical and physiological characteristics, 16S rRNA gene and periplasm nitrate reductase gene analysis. The optimal pH, temperature, carbon source, dissolved oxygen (DO), inoculum ratio were tested as well. RESULTS: Strain A-13 isolated from a drain outlet located in Gaoqi village, Shangjie town, Minhou county, Fuzhou, China, was a member of Pseudomonas stutzeri and its DNA sequence was most closely related to Pseudomonas stutzeri DSM 50283. The optimal conditions for its growth and denitrification were followed as: pH 6.5, 33 degrees C, 150 r/min, 5% inoculum rate and the best carbon source was sodium succinate. Under these conditions, the maximum removal capacity for NO3- was approximately 1900 mg/L. The strain could grow well in the medium with high salinity (10%) and could also use NO2- and NH(4+)-H as the sole nitrogen source. CONCLUSION: The isolated P. stutzeri, A-13 is a potential strain to treat wastewater with high salinity and/or eutrophication.