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AIM: To identify and characterize bacterium that possessed both the nitrogen removal activity and estrogen removal activity.METHODS:Semi-quantitative ammonia detection to determine the NH4+-N removal activity of Acinetobacter sp.T32 was carried out using the kit purchased from Luheng Biotech.Com.The concentrations of NH4+-N,NO2–-N and NO3–-N were also detected to determine the nitrogen removal activity.In addition,BPA degradation was simultaneously monitored by using HPLC.A subunit of ammonia monooxygenase(AMO)of Acinetobacter sp.T32,amoAAc,was cloned and characterized for its structural domain and homology analysis,and its transcription in the mRNA level by using real-time reverse transcriptase PCR.RESULTS: Acinetobacter sp.T32 almost 100%removed NH4+ at concentrations below 100 mg/L and 98%of total inorganic nitrogen from the aqueous phase after inoculated for 48 h,with only a trace production of NO2– and NO3–.Acinetobacter sp.T32 could also degrade BPA using BPA as sole carbon source,but with a lower efficiency.mRNA level of amoAAc was 22-fold and 12-fold increase in the presence of NH4+ and BPA,respectively.50 mg/L allylthiourea,the typical inhibitor of AmoA of autotrophic nitrifying bacteria,down-regulated the mRNA level of amoAAc.LD50 studies revealed that Acinetobacter sp.T32 was non-toxic to Japanese flounder,which suggested that Acinetobacter sp.T32 can be safely used in water quality enrichment.CONCLUSIONS: An Acinetobacter sp.T32 was characterized to possess high removal efficiency of both nitrogen and BPA.60 mg/L NH4+-N and 1 μg/L BPA could be completely removed from the water sample.The gene encoding AmoAAc,the subunit AMO of Acinetobacter sp.T32,was cloned and characterized for the first time.AmoAAc contained the conserved AmoA domains and was significantly up-regulated in mRNA level in the presence of NH4+ and BPA,respectively.Allylthiourea partly interfere the function of AmoAAc during the process of BPA degradation,but not effective as the inhibitory effect on the process of NH4+ transformation.Acinetobacter sp.T32 was environmental friendly in terms of its LD50 to J.flounder.Combination of these results suggested that our study supply new resource and strategy that can be potentially applied in the treatment of NH4+ and BPA contamination,for the high and rapid removal activity possessed by the heterotrophic nitrifier Acinetobacter sp.T32.