title: Evaluation of quantitative PCR combined with PMA treatment for molecular assessment of microbial water quality.
abstract: Microbial water quality assessment currently relies on cultivation-based methods. Nucleic acid-based techniques such as quantitative PCR (qPCR) enable more rapid and specific detection of target organisms and propidium monoazide (PMA) treatment facilitates the exclusion of false positive results caused by DNA from dead cells. Established molecular assays (qPCR and PMA-qPCR) for legally defined microbial quality parameters (Escherichia coli, Enterococcus spp. and Pseudomonas aeruginosa) and indicator organism group of coliforms (implemented on the molecular detection of Enterobacteriaceae) were comparatively evaluated to conventional microbiological methods. The evaluation of an extended set of drinking and process water samples showed that PMA-qPCR for E. coli, Enterococcus spp. and P. aeruginosa resulted in higher specificity because substantial or complete reduction of false positive signals in comparison to qPCR were obtained. Complete compliance to reference method was achieved for E. coli PMA-qPCR and 100% specificity for Enterococcus spp. and P. aeruginosa in the evaluation of process water samples. A major challenge remained in sensitivity of the assays, exhibited through false negative results (7-23%), which is presumably due to insufficient sample preparation (i.e. concentration of bacteria and DNA extraction), rather than the qPCR limit of detection. For the detection of the indicator group of coliforms, the evaluation study revealed that the utilization of alternative molecular assays based on the taxonomic group of Enterobacteriaceae was not adequate. Given the careful optimization of the sensitivity, the highly specific PMA-qPCR could be a valuable tool for rapid detection of hygienic parameters such as E. coli, Enterococcus spp. and P. aeruginosa.
authors.affiliation: AIT Austrian Institute of Technology GmbH, Bioresources Unit, Konrad Lorenz Strasse 24, A-3430 Tulln, Austria. Electronic address: Eva.Gensberger@ait.ac.at.
authors.forename: Eva Theres
authors.initials: ET
authors.lastname: Gensberger
authors.affiliation: AIT Austrian Institute of Technology GmbH, Bioresources Unit, Konrad Lorenz Strasse 24, A-3430 Tulln, Austria.
authors.forename: Marlies
authors.initials: M
authors.lastname: Polt
authors.affiliation: AIT Austrian Institute of Technology GmbH, Bioresources Unit, Konrad Lorenz Strasse 24, A-3430 Tulln, Austria.
authors.forename: Marianne
authors.initials: M
authors.lastname: Konrad-Köszler
authors.affiliation: AIT Austrian Institute of Technology GmbH, Environmental Resources & Technologies Unit, Konrad Lorenz Strasse 24, A-3430 Tulln, Austria.
authors.forename: Paul
authors.initials: P
authors.lastname: Kinner
authors.affiliation: AIT Austrian Institute of Technology GmbH, Bioresources Unit, Konrad Lorenz Strasse 24, A-3430 Tulln, Austria.
authors.forename: Angela
authors.initials: A
authors.lastname: Sessitsch
authors.affiliation: AIT Austrian Institute of Technology GmbH, Bioresources Unit, Konrad Lorenz Strasse 24, A-3430 Tulln, Austria.
authors.forename: Tanja
authors.initials: T
authors.lastname: Kostić
mesh_terms: D001317:Austria; D001386:Azides / Q000494:pharmacology*; D017931:DNA Primers / Q000235:genetics; D060766:Drinking Water / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011419:Propidium / Q000031:analogs & derivatives* / Q000494:pharmacology; D014871:Water Microbiology; D060753:Water Quality / Q000592:standards*
chemical_list: D001386:Azides; D017931:DNA Primers; D060766:Drinking Water; C533957:propidium monoazide; D011419:Propidium
keywords: Microbiological water quality assessment; Propidium monoazide; Quantitative PCR; Sensitivity; Specificity