SIMPLE CONCENTRATION METHOD FOR BACTERIOPHAGES OF BACTEROIDES-FRAGILIS IN DRINKING-WATER

A membrane of inorganic material with a honeycomb pore structure was u sed to concentrate phages infecting Bacteroides fragilis from drinking water. Phages were removed from the membrane with 0.25 M glycine buff er pH 9.5. Phages were not inactivated by storage in this buffer neutr alized to pH 7.0 for at least 9 days at 4 degrees C. The method allows recovery of around 50% in drinking water. When the turbidity of the w ater increased, the efficiency of the concentration decreased markedly . The efficiency of concentration was evaluated versus a presence/abse nce test in 317 water samples with turbidity level below the threshold of drinking water. Results obtained by concentration of 11 provided d ata which were significantly more informative than the presence/absenc e tests carried out on 100 ml. A number of additional tests carried ou t with both somatic and F-specific coliphages indicated that these con clusions can be extended to these groups of bacteriophages.