Evaluation of Pathogen Disinfection Efficacy by Chlorine and Monochloramine Disinfection Based on Quantitative PCR Combined with Propidium Monoazide (PMA-qPCR)
基于PMA-定量PCR选择性检测技术的病原菌消毒特性研究

A novel detection method of quantitative PCR combined with a DNA intercalating dye propidium monoazide (PMA-qPCR) was developed and then applied to analyze inactivation efficacy of chlorine and monochloramine on E.coli as a representative organism. The results shows that PMA removed 99.94% and 99.99% DNA from non-viable E.coli and Salmonella cells respectively and PMA-qPCR could effectively differentiate viable bacteria from non-viable bacteria; According to the first-order kinetic model, the inactivation coefficients on E.coli obtained by PMA-qPCR were 2.24 L·(mg·min)-1 and 0.0175 L·(mg·min)-1 for chlorine and monochloramine respectively, both of which were lower than those obtained by traditional plating counting method. In order to inactivate 99% of E.coli, the ct values by PMA-qPCR were 0.9 mg·L-1·min and more than 100 mg·L-1·min for chlorine and monochloramine while those by plating counting method were only 0.6 mg·L-1·min and 20 mg·L-1·min, respectively; E. coliconcentration detected by conventional qPCR kept almost the same when ct value increased, indicating that conventional qPCR was unable to evaluate inactivation efficacy of both chlorine and monochloramine disinfection. In summary, PMA-qPCR shows to be a promising method for evaluating disinfection efficacy by chlorine and monochloramine more accurately.