Evaluation of Bacteroides fragilis Bacteriophages as Indicators of the Virological Quality of Water

Bacteriophages infecting Bacteroides fragilis 40 were found in all kinds of sewage polluted samples. In contrast, they were never recovered either in non-faecally polluted samples or in samples only polluted by wildlife. In simulated laboratory experiments, a selected bacteriophage, B40-8, active against B. fragilis 40 did not replicate either in aerobiosis or under anaerobic conditions, when the culture medium was substituted by either fresh water, seawater or sediments. Inactivation rates of the same bacteriophage were studied in comparison with other viruses such as poliovirus 1, simian rotavirus SA11 and f2 coliphage, showing decay rates similar or inferior to the ones of the other viruses studied. Results herein shown indicate that bacteriophages infecting B.fragilis may be good candidates for a surrogate indicator of human viruses in the environment.