Detection of Infectious Enteroviruses, Enterovirus Genomes, Somatic Coliphages, and Bacteroides fragilis Phages in Treated Wastewater

Abstract

In this study, three types of treated wastewater were tested for infectious enteroviruses, the enterovirus genome, somatic coliphages, and Bacteroides fragilis phages. The aim of this work was to determine whether the presence of the two types of bacteriophages or of the enterovirus genome was a good indicator of infectious enterovirus contamination. The enterovirus genome was detected by reverse transcription-polymerase chain reaction. Infectious enteroviruses were quantified by cell culturing (BGM cells), and the bacteriophages were quantified by plaque formation on the host bacterium (Escherichia coli or B. fragilis) in agar medium. Forty-eight samples of treated wastewater were analyzed. Sixteen samples had been subjected to a secondary treatment for 8 to 12 h (A), 16 had been subjected to a secondary treatment for 30 h (B1), and 16 had been subjected to both secondary and tertiary treatments (B2). The mean concentrations of somatic coliphages were 4.9 × 104 PFU · liter−1 for treatment line A, 9.8 × 103PFU · liter−1 for B1, and 1.4 × 103 PFU · liter−1 for B2, with all the samples testing positive (100%). The mean concentrations of B. fragilis phages were 1.7 × 103 PFU · liter−1 for A (100% positive samples), 17 to 24 PFU · liter−1 for B1 (44% positive samples), and 0.8 to 13 PFU · liter−1 for B2 (6% positive samples). The mean concentrations of infectious enteroviruses were 4 most probable number of cytopathogenic units (MPNCU) · liter−1 for A (31% positive samples) and <1 MPNCU · liter−1 for B1 and B2 (0% positive samples). The percentages of samples testing positive for the enterovirus genome were 100% for A, 56% for B1, and 19% for B2. The percentages of samples testing positive for the enterovirus genome were significantly higher than those for infectious enteroviruses. This finding may have been due to the presence of noninfectious enteroviruses or to the presence of infectious enteroviruses that do not multiply in BGM cell cultures. However, under our experimental conditions, nondetection of the genome implies the absence of infectious viruses. There was a significant correlation between the concentration of somatic coliphages orB. fragilis phages and the presence of infectious enteroviruses or the presence of the enterovirus genome. However, the somatic coliphage concentration did not lead to fluctuations in the infectious enterovirus concentration, whereas the B. fragilis phage concentration did.

F+RNA coliphage typing for microbial source tracking in surface waters

“…We subsequently learned that these samples had been treated, but the analyses of these samples demonstrate the ability of coliphages to survive treatment processes where faecal coliforms cannot. This observation is consistent with previous studies that have detected coliphages and viruses in treated wastewaters (for example, Gantzer et al 1998) and demonstrates the inadequacy of bacterial indicators to estimate viral pollution.…”

Methods to detect infectious human enteric viruses in environmental water samples

“…CPE can be swelling, shrinking, rounding of cells to clustering or complete destruction of the monolayer (Leland and Ginocchio, 2007). This can also be done in a quantitative form and the virus can be enumerated as most probable number (MPN) (Chapron et al, 2000;Gantzer et al, 1998;Shieh et al, 2008) or tissue culture infectious dose (TCID50) units (Calgua et al, 2011;Enriquez and Gerba, 1995;Jiang et al, 2004;Kok et al, 1998). MPN test involves observation of CPE in monolayers inoculated with different dilutions of viral suspension and subsequent use of MPN table or MPN software program to determine the viral counts.…”

Correlation between bacterial indicators and bacteriophages in sewage and sludge

“…FRNAPH and BFRPH have been proposed as alternative indicators of viral health risk associated with shellfish (Dore et al, 2003;Muniain-Mujika et al, 2003). Gantzer et al (1998) report a significant correlation between SOMCPH and BFRPH and the presence of enteroviruses in wastewaters.…”