Impact of lytic phages infecting Salmonella enterica subspecies arizonae on physicochemical and microbiological water quality of the old Port of Bizerte (Tunisia, SW Mediterranean Sea)

Abstract

Phage therapy is among recent innovative technology to improve wastewater quality. Previous phage studies have focused on the interactions of phages with bacterial host cells or the impact of environmental conditions on phage-host cell dynamics. In this research, we particularly examined the impact of phages on a marine physicochemical and microbiological environmental characteristic. Following three days of incubation, seawaters receiving separately phage fBC-Eco01 (OM272052) and phage PA25, undergone a temperature increase of 1.7 °C and 2.5 °C, respectively. Seawater salinity values saved an increase in conductivity over time that ranged between 51.03 and 53.94 µS and from 51.04 to 53.7 μS for the phage PA25 and the phage fBC-Eco01, respectively. A significant decrease in dissolved oxygen levels of 2,1 mg/L were reported following the addition of both phages PA25 and fBC-Eco01 during three days of incubation, compared to a decrease of 1 mg/L in the control seawaters. The TOC increased from 0.33 ppm to 0.67 ppm in the presence of the PA25 phage and from 0.2 ppm to 1.51 ppm after the addition of the fBC-Eco01 phage, compared to control that saved values decreasing from 0.35 ppm to 0.05 ppm. The absorbance and fluorescence spectrophotometry values were also affected by phages addition. Moreover, phages addition reduced total aerobic mesophilic bacteria (TAMB) and Total aerobic thermophilic bacteria (TATB) abundance, corresponding to a decrease of 2 Ulog and 1 Ulog discharge, respectively following addition of PA25 and 3 Ulog and 2 Ulog discharge, respectively with addition of fBC-Ec01 phage.