Field of Science

thin lawns, feeble or absent phage

My phage titering gave disappointing results.  Three of the five lysates gave no plaques at all, and the other two gave small indistinct plaques that couldn't be accurately counted or characterized.

I took some photos of the plaques I did see.  The top photo is a section of one lawn, with several thousand tiny indistinct plaques.  (The blurry markings are the label on the bottom of the plate.)  The second photo is a closeup  of an area on another lawn where I had spotted more-dilute phage, taken with my iPhone's Olloclip zoom lens.  A few tiny plaques are visible, maybe 3, maybe 5.

For comparison, here's what nice plaques look like.  These are plaques of the E. coli phage lambda (source)

I won't be able to use these R. capsulatus phage for my GTA-vaccine experiments unless I can get better plaques.  I'll need to know whether the phage makes turbid or clear plaques, and I'll need to be able to count it accurately.

I can try using another strain as the host.  These lawns were made with a culture of strain YW1, the strain that these phage were originally isolated on.  I have several other strains, though I don't know if they are closely related.

I can also try changing the plating conditions.  I followed the protocol that I obtained from people who have worked with these phage, but perhaps I could grow the cells to a different density, or incubate the plates at a different temperature.   I'll ask the experts for advice.

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