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Evaluation of B acteroides fragilis GB ‐124 bacteriophages as novel human‐associated faecal indicators in the U nited S tates
Author(s) -
McMinn B.R.,
Korajkic A.,
Ashbolt N.J.
Publication year - 2014
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12252
Subject(s) - bacteroides fragilis , sewage , biology , coliphage , feces , bacteroides , bacteriophage , microbiology and biotechnology , fecal coliform , indicator organism , veterinary medicine , effluent , bacteria , ecology , antibiotics , escherichia coli , water quality , environmental science , medicine , biochemistry , genetics , environmental engineering , gene
Phages infecting human‐associated B acteroides fragilis ( GB ‐124 phages) have been employed in the European Union ( EU ) to identify human faecal pollution, but their utility for the United States was unclear. Primary sewage samples were collected seasonally from seven wastewater treatment plants ( WWTP ) across the continental United States, and more time‐intensive sampling was conducted at local WWTP s. All samples were assayed for plaque‐forming units ( PFU ) of GB ‐124 phages, somatic and FRNA ‐specific coliphages, as well as adenoviruses (by quantitative PCR [ qPCR ]). Animal faecal samples (>250) from 14 different species were tested for the presence of the three phage groups. GB ‐124 phages were consistently detected in sewage (10–10 2 PFU ml −1 ), but not in animal faeces. While density estimates of both coliphages in sewage were approximately one order of magnitude higher than GB ‐124 phages, they were both randomly detected in animal faecal samples (10 2 –10 5 g −1 dry weight). Stability of all three phages was inversely proportional to temperature; persistence was greatest at 5°C compared to 20 and 35°C, where no phages were detectable after a week. In summary, GB ‐124 phages appear to be a feasible alternative indicator organism and benefit from being sewage associated, while providing an inexpensive detection technique for infectious virions. Significance and Impact of the Study Bacteroides fragilis GB ‐124 phages appear to be restricted to human sewage sources in the United States, being absent from 264 animal faecal samples from 14 different species and present in approx. 90% (34/38) of primary sewage effluent samples collected across the country. Although somatic and F‐specific coliphages were present in sewage samples at higher densities, unlike GB ‐124 phages, both coliphage types were also detected in animal faecal samples. Hence, GB ‐124 phages may prove to be a useful novel indicator group for human faecal pollution in the continental United States.