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R. L. Whitman, Z. Ge, M. B. Nevers, A. B. Boehm, E. C. Chern, R. A. Haugland, A. M. Lukasik, M. Molina, K. Przybyla-Kelly, D. A. Shively, E. M. White, R. G. Zepp and M. N. Byappanahalli, “Relationship and Variation of qPCR and Culturable Enterococci Estimates in Ambient Surface Waters Are Predictable,” Environmental Science & Technology, Vol. 44, No. 13, 2010, pp. 5049-5054. doi:10.1021/es9028974

has been cited by the following article:

• TITLE: Destruction of Escherichia coli and Broad-Host-Range Plasmid DNA in Treated Wastewater by Dissolved Ozone Disinfection under Laboratory and Field Conditions

  AUTHORS: Kyle L. Asfahl, Mary C. Savin

  KEYWORDS: Disinfection; Wastewater Treatment; Ozone; qPCR; Plasmid; Broad-Host-Range Plasmid; DNA;Escherichia coli

  JOURNAL NAME: Advances in Microbiology, Vol.2 No.1, March 23, 2012

  ABSTRACT: Broad-host-range plasmids are frequently associated with antibiotic resistance genes and can quickly spread antibiotic resistant phenotypes among diverse bacterial populations. Wastewater treatment plants have been identified as reservoirs for broad-host-range plasmids carrying resistance genes. The threat of broad-host-range plasmids released into the environment from wastewater treatment plants has identified the need for disinfection protocols to target broad-host- range plasmid destruction. Here we evaluate the efficacy of dissolved ozone at 2 and 8 mg·L–1 as a primary means for the destruction of broad-host-range plasmid and chromosomal DNA in simulated effluent. Pilot-scale tests using an experimental unit were carried out in municipal wastewater treatment plant effluent and compared with ultraviolet (UV)-irradiation and chlorination methodologies. Genes specific to Escherichia coli (uidA) and IncP broad-host-range plasmids (trfA) were monitored using real-time quantitative polymerase chain reaction (qPCR), and total DNA was monitored using absorbance spectroscopy. In wastewater treatment plant experiments, E. coli qPCR results were compared to a recognized culture-based method (Colilert?) for E. coli. In laboratory experiments, dissolved ozone at 8 mg·L–1 significantly destroyed 93% total, 98% E. coli, and 99% of broad-host-range plasmid DNA. Ozonation, UV-irradiation, and chlorination significantly reduced DNA concentrations and culturable E. coli in wastewater treat- ment plant effluent. Chlorination and UV disinfection resulted in 3-log decreases in culture-based E. coli concentrations in wastewater treatment plant effluent while changes were not significant when measured with qPCR. Only ozonation significantly decreased the IncP broad-host-range plasmid trfA gene, although concentrations of 2.2 × 105 copies trfA·L–1 remained in effluent. Disinfection processes utilizing high dissolved ozone concentrations for the destruction of emerging contaminants such as broad-host-range plasmid and total DNA may have utility as methods to ensure downstream environmental health and safe water reuse become more important.