%0 Journal Article
%T Destruction of <i>Escherichia coli</i> and Broad-Host-Range Plasmid DNA in Treated Wastewater by Dissolved Ozone Disinfection under Laboratory and Field Conditions
%A Kyle L. Asfahl
%A Mary C. Savin
%J Advances in Microbiology
%P 1-7
%@ 2165-3410
%D 2012
%I Scientific Research Publishing
%R 10.4236/aim.2012.21001
%X 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<sup>¨C1</sup> 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 <i>Escherichia coli</i> (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, <i>E. coli</i> qPCR results were compared to a recognized culture-based method (Colilert<sup>?</sup>) for <i>E. coli</i>. In laboratory experiments, dissolved ozone at 8 mg¡¤L<sup>¨C1</sup> significantly destroyed 93% total, 98% <i>E. coli</i>, and 99% of broad-host-range plasmid DNA. Ozonation, UV-irradiation, and chlorination significantly reduced DNA concentrations and culturable <i>E. coli</i> in wastewater treat- ment plant effluent. Chlorination and UV disinfection resulted in 3-log decreases in culture-based <i>E. coli</i> 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 ¡Á 10<sup>5</sup> copies trfA¡¤L<sup>¨C1</sup> 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.
%K Disinfection
%K Wastewater Treatment
%K Ozone
%K qPCR
%K Plasmid
%K Broad-Host-Range Plasmid
%K DNA
%K &lt
%K i&gt
%K Escherichia coli&lt
%K /i&gt
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=18055