Biological denitrification reaction can be achieved under aerobic environment. Few aerobic denitrifiers using nitrite as sole nitrogen source were identified. Using nitrite as the sole nitrogen source, this work assessed the denitrification activity of yy7, an aerobic heterotrophic denitrifier identified as Pseudomonas sp. (94% similarity) by 16S rRNA sequencing analysis. The logistic equation describes the cell growth curve, yielding a generation time of 2.9 h at an initial 18 mg l(-1) NO2--N. Reduction of NO2--N was primarily achieved during its logarithmic growth phase, and was accompanied by an increase in suspension pH and near complete consumption of dissolved oxygen. Three genes relating to nirK, norB, and nosZ were noted to involve in isolate strain. Isolate yy7 can survive and remove up to 40 mg l(-1) NO2--N and, hence, can be applied as an effective aerobic denitrifier during simultaneous nitrification and denitrification via nitrite processes. (C) 2011 Elsevier Ltd. All rights reserved.