| Summary: | A heterotrophic nitrification and aerobic denitrification bacterium, strain D51, was identified as <i>Arthrobacter nicotianae</i> based on morphological, phospholipid fatty acids (PLFAs), and 16S rRNA gene sequence analyses. Further tests demonstrated that strain D51 had the capability to use nitrite, nitrate, or ammonium as the sole nitrogen source in the presence of Cu<sup>2+</sup>. The maximum removal efficiencies of nitrite, nitrate and ammonium were 68.97%, 78.32%, and 98.70%, respectively. Additionally, the maximum growth rate and denitrification capacity of this strain occurred in the presence of 0.05 mg·L<sup>−1</sup> of Cu<sup>2+</sup>.However, the growth and aerobic denitrification capacity were intensively inhibited by Cu<sup>2+</sup> at ≥0.1 mg·L<sup>−1</sup>. Moreover, gas chromatography indicated that a portion of the nitrogen was transformed into N<sub>2</sub>O when the nitrite, nitrate, and ammonium were separately used as the sole nitrogen source. This is the first study of the nitrification and denitrification ability of <i>Arthrobacter nicotianae</i> under aerobic conditions, and the first experiment to investigate the impact of Cu<sup>2+</sup> concentration on the growth and denitrification ability of this bacteria. The results presented herein extend the known varieties of heterotrophic nitrifying⁻aerobic denitrifying bacteria and provide useful information regarding the specific bacteria for nitrogen bioremediation of industrial wastewater containing Cu<sup>2+</sup>.
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