Abstract: [Objective] The aim of this study was to investigate the effect of potassium ferrate on plasmid-mediated colistin resistance gene mcr-1. [Method] The absolute abundance of mcr-1 gene in water was determined by real-time fluorescence quantitative PCR using four-factor and three-level orthogonal method. The elimination rate of mcr-1 gene was used as an index to investigate different factors and levels （potassium ferrate: 7.09 mg/L, 14.17 mg/L, 21.26 mg/L; temperature: 40 ℃, 50 ℃, 60 ℃; reaction time: 5 min, 15 min, 30 min; pH: 5, 7, 9） on mcr-1 gene content. [Result] Among the four factors, the greatest influence on the absolute abundance of mcr-1 gene was the dosage of potassium ferrate, followed by the reaction pH and reaction time, and the least influence was the reaction temperature. The level combination with the best effect on mcr-1 gene ablation was A₃B₃C₁D₃, which was treated with 21.26 mg/L potassium ferrate （6 mg/L in Fe） for 15 min at a reaction pH of 5 and a reaction temperature of 60 ℃, and the ablation rate of the mcr-1 gene under this condition was 55%. However, the copy number of mcr-1 gene increased under certain combinations of factors. [Conclusion] Potassium ferrate could affect mcr-1 gene levels by altering DNA concentrations. Under appropriate conditions, potassium ferrate abrogated the mcr-1 gene in the water. However, under certain combinations of factor levels, mcr-1 gene replication will increase.

Key words: mcr-1, potassium ferrate, resistance gene, orthogonal test, environment