Nitrogen　removal　by　a　newly　discovered　Pseudomons　sp.　strain,　DK1,　isolated　from　activated　sludge　was　investigated.　Using　glucose　as　a　carbon　source　and　a　n(C)/n(N)　ratio　of　five,　batch　experiments　showed　that　the　aerobic　denitrification　removal　rate　was　4.09　mg·(L·h)-1　and　4.43　mg·(L·h)-1with　NaNO3　or　NaNO2,　respectively.　Completely　nitrogen　removal　was　achieved　when　using　these　two　nitrogen　sources.　DK1　was　also　found　to　heterotrophically　remove　NH4+-N　at　a　rate　of　2.32　mg·(L·h)-1　and　to　carry　out　anoxic　denitrification　of　a　range　of　concentrations　of　NO2--N　(from　about　100　to　300　mg·L-1)　within　a　maximum　of　36　hours　of　inoculation.　In　the　presence　of　both　NO3--N　and　NO2--N,　DK1　was　found　to　preferentially　denitrify　NO3--N.　Simultaneous　nitrification　and　denitrification　(SND)　capacity　of　the　DK1　strain　was　observed　when　using　ammonium　and　nitrate　or　ammonium　and　nitrite　and　the　corresponding　nitrogen　removal　rates　reached　as　high　as　95.06%　and　94.69%　within　30　hours　of　inoculation,　respectively.　Ammonium　with　both　nitrate　and　nitrite　resulted　in　a　100%　nitrogen　removal　within　the　same　time　frame.　The　ability　to　achieve　SND　and　to　denitrify　both　NO3--N　and　NO2--N　makes　the　DK1　strain　potentially　useful　for　future　application　in　nitrogenous　wastewater　treatment.　©　2017,　Science　Press.　All　right　reserved.