[Disinfection Action of Ultraviolet Radiation and Chlorination on Escherichia coli and Poliovirus].

We chose Escherichia coli ( E. coli ) and poliovirus as a typical pathogenic bacterium and virus, respectively. The effects of two typical disinfectants (chlorine and ultraviolet) on each of them were investigated based on microbial culture and quantitative PCR methods. The results showed that Poliovirus was appreciably more resistant to chlorine (required disinfection dose for 1-log microbial reduction:10.14 mg·L ^-1 ·min for E. coli ; 19.2 mg·L ^-1 ·min for poliovirus) and ultraviolet (UV) light (required UV dose for 1-log microbial reduction:1.81 mJ·cm ^-2 for E. coli ; 6.37 mJ·cm ^-2 for poliovirus) than E. coli for the microbial culture. For PCR, this study revealed that 1-log gene reduction required UV doses and ct values of at least one to two orders of magnitude higher than that for the microbial culture. The damage of RNA in Poliovirus was more seriously than that of DNA in E. coli . Single-stranded RNA was more sensitive to UV irradiation than DNA. The result evaluated with the quantitative PCR method showed opposite result to that of the traditional culture method in which the Poliovirus was more tolerant. The required UV doses for 1-log nucleic acid reduction were 135 mJ·cm ^-2 and 270.3 mJ·cm ^-2 for E. coli and poliovirus, respectively. Nucleic acid damage required a higher dose of disinfectants than microbial inactivation, which was probably attributed to the phenomenon of viable but non-culturable (VBNC) cells, other molecular targets of inactivation and the persistence of nucleic acid after cell death.