Isolation of aerobic denitrifiers and characterization for their potential application in the bioremediation of oligotrophic ecosystem
ABSTRACT 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.
Annals of Microbiology 01/2014; DOI:10.1007/s13213-014-0952-6 · 1.04 Impact Factor
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ABSTRACT: A novel heterotrophic nitrifying and aerobic denitrifying bacterium, KTB, was isolated from activated sludge flocci collected from a biological aerated filter according to the modified Takaya method and identified as Pseudomonas stutzeri by 16S rDNA gene sequence analysis. When shaking-cultured in the presence of 4.331 mmol/L of nitrate, 4.511 mmol/L of nitrite and 4.438 mmol/L of ammonium, the strain grew fast, with μmax being 0.42, 0.45, and 0.56/h, and displayed high nitrogen removal efficiency, with nitrogen removal rate being 0.239, 0.362, and 0.361 mmol/L/h and nitrogen removal ratio being 99.1, 100.0, and 100.0% in 18 h, respectively. The removal mainly occurred in the logarithmic phase. Nitrite accumulation did not affect denitrification performance. Nitrate concentration was below the detectable limit during the whole growth cycle when ammonium was used as sole nitrogen source. It tolerated high DO level and exhibited excellent aggregation ability. A possible pathway involved in the nitrogen removal process, which demonstrated a full nitrification and denitrification route, was speculated. The strain might be a great candidate for biological removal of nitrogen compounds from wastewater.Biotechnology and Bioprocess Engineering 03/2014; 19(2):231-238. DOI:10.1007/s12257-013-0580-1 · 1.22 Impact Factor
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ABSTRACT: a b s t r a c t The feasibility of implementing a novel strategy to start up and stably operate a partial nitritation (PN) process in an internal-loop airlift reactor was investigated. The results suggested that the PN process was successfully set up through initial complete nitrification followed by adjusting the alkalinity-to-ammonium ratio (Alk=NH þ 4 —N), also known as the 'initial complete nitrification and subsequent partial nitrification' (CN in –PN sub) strategy. A high nitrite accumulation ratio of approximately 98% and a maximum nitrite production rate of 0.91 kg N m À3 day À1 were attained under the conditions of 1.0 mol mol À1 Alk=NH þ 4 —N, 1.24 ± 0.71 mg L À1 dissolved oxygen, 3.99 ± 2.29 mg L À1 free ammonia and 0.69 ± 0.30 mg N L À1 free nitrous acid. The stabilized effluent with an NO À 2 —N=NH þ 4 —N ratio of 1.15 ± 0.06 was suitable for subsequently feeding the anaerobic ammonium oxidation (ANAMMOX) process. The modified Stover-Kincannon model was used to analyze the kinetic parameters, and the sat-uration constant (K B) and maximum ammonium utilization rate (U max) were determined to be 5.8 and 5.4 kg m À3 day À1 , respectively. Ó 2013 Elsevier B.V. All rights reserved.Separation and Purification Technology 11/2013; 120. DOI:10.1016/j.seppur.2013.10.024 · 3.07 Impact Factor