Enhancement mechanism of copper on heterotrophic nitrification-aerobic denitrification by cold-adapted Pseudomonas sp. NY1: Insights from genome and transcriptome.

Low concentrations of copper ions (Cu2+) can promote the heterotrophic nitrification-aerobic denitrification (HN-AD) ability of cold-adapted Pseudomonas sp. NY1, but the exact promotion mechanisms remain unclear. In this study, nitrogen balance data revealed that the removal rates of NO2--N and total nitrogen increased by 0.37 mg/L/h and 0.28 mg/L/h after addition of 0.05 mg/L Cu2+. The genetic bases for cold-adapted, copper-resistant, and multiple-nitrogen metabolism pathways of strain NY1 were determined by whole genome sequencing. Transcriptome and reverse transcription-quantitative polymerase chain reaction analysis revealed that strain NY1 promoted amino acid and energy production by the upregulation of assimilatory nitrite reduction to ammonium in response to copper stress. These results provided insights into the positive effects of Cu2+ on HN-AD bacteria by accelerating the removal of ammonium and nitrite, and advancing the application and development of HN-AD bacteria in copper-containing and low-temperature wastewater.