Hello, I'm working with lambda phage, and have worked with other temperate phage in the past. I'm currently trying to definitively determine if the large plaques seen on the picture attached are indeed lysogenic plaques. Smaller, typical lambda lytic plaques can be seen on the plate as well. Can anyone offer any insight? Thanks in advance!
Maybe. It looks like plaques formed by phage. what you can do is isolate one plaque >>>>suspend in a buffer (we use SM buffer)>>> Make a double layer plate of the host bacteria>>>>let the soft agar get set (20-30 mins)>>>>place a few spots (1-5ul) of the well-mixed phage suspension (phage in buffer) on the above plate ...incubate for 5-6 hours to 48 hours and check for cleared out zone (lysis). The incubation time depends on bacterial growth and phage lysis.
Sometimes lytic bacteria also show such plaques (like the ones in the photo). In most cases, treatment with CHCl3 will kill the bacteria but not the phage.
I doubt it. It is really hard to tell from the picture what is going on, but the big "plaques" look to me like water droplets changed the consistency of the lawn. I have never seen lambda plaques get much bigger than the typical plaques you also see on that plate.
I would note that with wild type lambda the normal plaques are turbid, which is a mixture of a lytic propagation followed by some lysogens growing up in the plaque. A truly lytic infection would yield clear plaques and not turbid plaques, which can happen with some c mutants of lambda. If you had a totally lysogenic phage (ie never went through a lytic cycle) there would be no plaque at all.
Michael J. Benedik ah, that makes sense. I thought they looked pretty strange for Lambda. Thanks for your input!
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