Jumbo Phages?

Our Phages have been exhibiting some strange behaviour lately, from plaques only appearing around the edge of the plate to phage samples ceasing in producing plaques. I have successfully isolated a phage, but I have been struggling to get a large amount of the little guy. After many discussions and some research, we may have found an answer to do with the size of our Phages and their ability to diffuse through the agar.

Phages vary in size and shape greatly, from filamentous Phages which can be up to 2000 nm in length (inovirus) to the more familiar capsid and tail Phages, which can range from 26 nm to 340 nm. Phages cannot swim or move voluntarily though a medium, so their main method of transportation is diffusion. The size of a phage impacts how quickly it diffuses through a medium, and a less dense substance will allow for faster diffusion of the phage.

I noticed in the morphology of my plaques that they are all very small, pin-prick like plaques. It is possible that their inability to produce the desired web-like pattern is due to them being too large to diffuse through the agar mixture. Our lab tech has made the agar at 0.35%. According to the graph here (figure 1) this could be much too high for certain Phages to grow – larger Phages. In the lab today I plated four different agar concentrations: 0.7%, 0.35%, 0.17% and 0.085%. While the last plate may not set, my biggest hope is for the 0.17% plate.

I will post an update with the results of this experiment in the next few days. Fingers crossed!

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3 Responses to Jumbo Phages?

  1. nathanalexanderlong says:

    I have been having the same problem with my phage too (along with most of the class).The phage I have been getting (if any) have been tiny. Using this new concentration however has unfortunately proven to be a hindrance as well as helping as we are now having trouble with the agar not setting. Despite this the sample i plated with the 0.175% agar showed some much more promising plaques. We are now proceeding with an intermediate concentration of agar fingers crossed i will be able to get somewhere with this now 🙂

  2. sarahlomas19 says:

    This was a great idea Sophie! It gave me hope, for a little while, that maybe my phages would show themselves again. However it wasn’t the case – my phages must have died in storage. I had trouble with the 0.17% agar setting properly though. Did you not have this problem Nathan? Good luck with the rest of your phage hunting!

  3. Sophie P says:

    It seems that something went wrong with the agar. The lower concentration agar did have problems setting, the 0.17 and 0.085 didn’t set well and had a lot of moisture. It seemed like the 0.17 plates indeed had more plaques visible, but due to the poor setting this was increased to 0.215%. Unfortunately, more problems meant this wasn’t setting well either, making it difficult to tell if my Phages were still present.
    A later spot test confirmed that they had mysteriously disappeared, like many other’s.

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