Half-life of bacteriophages in sterile filtered sewage water - (Nov/11/2011 )

I am about to conduct a plaque assay with an E. coli strain (TG1), that is previously verified compatible for interaction (infection) with a bacteriophage solution (several bacteriophages). However, the sample of bacteriophages I have, currently some 25 - 35 ml stored in a Falcon tube in a cold room, have not been in use for perhaps up to 2 months (Only stored). The sample derives from a sewage water plant and it has been sterile filtered and also tested for bacteriophages, with positive results (It was not done by me).
However, the question is: What are the chances, the likeability, that living bacteriophages still exist in this sample? Alive and able to infect and lyse bacteria, thus making it possible to conduct the planned plaque assay?! I.e., I am wondering about the half-life of phages when stored in the described conditions!?

Best regards,
Vector Inoculator

I'd say it depends on which types of phage you have in your falcon, but in my experience 2 months in the fridge should be OK. Just don't freeze-thaw them. I think phage are well adapted to surviving for a long time outside cells. I am no phage specialist, but I've done a lot of phage display experiments and the titer of my phage stock in the fridge did not drop noticeably in two months.

Why not run the experiment yourself? A simle plaque assay in stability context should work.

Thanks a lot for the replies. And sorry for the late reply!
The pre-test confirmed plenty of plaques on the agar plates, thus verifying that bacteriophages were present in the sewage plant water sample at my disposal. I later did several plaque assays with it. I also read in a paper about some t-phages that it should be possible to store them for 2 months in the fridge easily.

Phil Geis: I asked because I short of time and wanted a comment about the likelihood of active phages in advance/at the same time of the trials.

Best regards,
Jim (Vector Inoculator)

ps) I usually dont work with phages and bacteria, but inoculate (infect) my own test organisms with viruliferous half-winged insects, as vectors.