DETECTION OF INFECTIOUS ENTEROVIRUSES, ENTEROVIRUS GENOMES, SOMATIC COLIPHAGES, AND BACTEROIDES-FRAGILIS PHAGES IN TREATED WASTE-WATER

In this study, three types of treated wastewater,were tested for infec tious enteroviruses, the enterovirus genome, somatic coliphages, and B acteroides fragilis phages. The aim of this work was to determine whet her the presence of the two types of bacteriophages or of the enterovi rus genome was a good indicator of infectious enterovirus contaminatio n, The enterovirus genome was detected by reverse transcription-polyme rase chain reaction, Infectious enteroviruses were quantified by cell culturing (BGM cells), and the bacteriophages were quantified by plaqu e 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 x 10(4) P FU . liter(-1) for treatment line A, 9.8 x 10(3) PFU . liter(-1) for B 1, and 1.4 x 10(3) PFU . liter(-1) for B2, with all the samples testin g positive (100%). The mean concentrations of B. fragilis phages were 1.7 x 10(3) 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 (MP NCU) liter(-1) for A (31% positive samples) and <1 MPNCU liter(-1) for B1 and B2 (0% positive samples). The percentages of samples testing p ositive for the enterovirus genome were 100% for A, 56% for B1, and 19 % for B2, The percentages of samples testing positive for the enterovi rus genome were significantly higher than those for infectious enterov iruses. This finding may have been due to the presence of noninfectiou s enteroviruses or to the presence of infectious enteroviruses that do not multiply in BGM cell cultures. However, under our experimental co nditions, nondetection of the genome implies the absence of infectious viruses. There was a significant correlation between the concentratio n of somatic coliphages or B. fragilis phages and the presence of infe ctious enteroviruses or the presence of the enterovirus genome. Howeve r, the somatic coliphage concentration did not lead to fluctuations in the infectious enterovirus concentration, whereas the B. fragilis pha ge concentration did.