Rapid concentration of bacteriophages from large volumes of freshwater: evaluation of positively charged, microporous filters.

Microporous, positively charged Zeta Plus 60 S filters were evaluated for bacteriophage recovery from large volumes of natural water. A variety of phages adsorbed efficiently to the filter medium at water pH levels below neutrality, but adsorption was reduced above pH 7. Adsorbed phages were easily eluted with an arginine/1% beef extract solution, pH 9.0. A concentration procedure suitable for the field isolation of bacteriophages from large volumes of river water was devised. The procedure involves, (1) prefiltration through 10" cartridge depth filters, (2) adjustment of water pH to pH 5.5--6.0, (3) adsorption of the phages on to Zeta Plus 60 S filters, (4) elution of bound phage in a small volume of eluent, (5) secondary concentration by ultrafiltration of the resulting eluates. Using this procedure, bacteriophages in 65 1 of river water was concentrated to 35 ml with recoveries in the range 50--60%.