Decay comparison of bacteriophages pp7 and p22 in water matrices, under different environmental conditions: detection by culture-based methods and qPCR.

CORIMAYO SN; MAIDANA-KULESZA MN; GUTIÉRREZ-CACCIABUE D; RAJAL VB; POMA HR

Viena

Congreso; IWA 20th International Symposium on Health Related Water Microbiology; 2019

Health Related Water Microbiology

Virus behavior in water is usually influenced by different factors. The presence of solidparticles is quite significant since they confer protection to them but this will depend onparticle type, size and concentration, physicochemical properties of virus, ambientconditions, among others. The aim of this work was to compare the persistence of twophages used as RNA and DNA virus models (pp7 and p22) under different ambientconditions. A group synthetic water matrices were prepared in 500 ml-glass beakersusing Phosphate Buffer Solution (PBS). A smallest particle size found (<0.074 mm) inriver bed was chosen and added in each beaker in two concentrations: 5 and 0.5 g/l(high and low respectively). Then, stocks of bacteriophages pp7 (Pseudomonasaeruginosa) or p22 (Salmonella) were prepared and spiked in known concentrations indifferent water matrices. Beakers with virus but without particles were used as controls.Two temperature (25°C and 12 °C) and two conductivities values (130 and 1300µS/cm) were selected to simulate ambient conditions. Water samples were taken fromthe surface of each beaker to evaluate virus disappearance over time. After a while,resuspension was done in all matrices and a last sample was removed and analyzed.Turbidity decay was also measured. Virus detection was done by plate count andqPCR. Kinetic parameters were calculated throughout a first-order decay model.Results showed that virus persistence was greater at low temperature, highconductivity and low solids particle concentration in water (measured through bothplate count and qPCR). The persistence of the p22 phage was greater than pp7 in allthe environmental conditions evaluated, being more marked for nucleic acids detection.Phage count did not increase after resuspension. Knowing virus persistence in water isimportant as it will allow a better understanding of the health risk involved.