Isolation of aerobic denitrifiers and characterization for their potential application in the bioremediation of oligotrophic ecosystem.

In recent years, nitrogen pollution has been increasingly serious in environmental waters in China, especially in drinking source. Seven predominant aerobic denitrifiers were isolated and characterized from the oligotrophic ecosystems. Based on their phenotypic and phylogenetic characteristics, the isolates were identified as the genera of Pseudomonas, Achromobacter and Acinetobacter, and all isolates could express periplasmic nitrate reductase which was essential for the aerobic denitrification. The growth rates of the isolates were at 0.30-0.83 h(-1), and obvious denitrification occurred when the dissolved oxygen (DO) level maintained at 3-10 mg L(-1). The isolates were able to conduct heterotrophic nitrification for realizing completely nitrogen removal in aerobic oligotrophic niche. Furthermore, three strains especially Pseudomonas sp.3-7 showed outstanding capacities of extracellular polymeric substances (EPS) secretion and aggregation. Results demonstrated that the isolation of aerobic denitrifiers favored the bioremediation of oligotrophic ecosystems. Crown