Question

Should you be able to see a bacteriophage on an inoculation loop? For class, I am working on isolating a bacteriophage and I feel at times confused on what I should be expecting. I labeled the clear zones that are suspected bacteriophage and when I rested my inoculation loop on top of the area, I see nothing and feel nothing (I don't know what I expected, but it just makes me apprehensive that I'm not doing this right?) I, then, put the inoculation tube into a labeled tube with phage buffer that will go into a new plate for a spot test just as if I got something. 17 hours later, I don't see anything yet on the plate and am not sure if I should be seeing anything by now.

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Edit: I am mainly looking for an answer to the first question, but really any help would be greatly appreciated.

Answer 1

No. You should not be able to see the bacteriophage. Bacteriophage sizes are in nanometers. As a comparison, bacterial cells are in the micrometer range (10³ of a bacteriophage) and you still do not see bacterial cells.

It takes roughly 1-2 days for spot test results. It is always a good idea to have positive and negative controls. The positive control would be a sample of bacteriophage you know affects the bacteria and the negative control would be just a drop of phage buffer. If you see a clear zone for the positive control and no change for the negative control, you can be confident that you have carried out the protocol correctly.

In case the you already know the bacteriophage you are trying to isolate affects the bacteria and you still do not see a clear zone, you can try repeating the experiment with fresh samples and buffers.