8 thoughts on “P27 – Ogren

  1. I may have missed this, but what is the significance behind the titer? I know it calculates plaque forming units, but why is it important?

    1. Finding the titer of a phage is important because it determines the amount of viable phage in a sample. This is important to know when archiving your phage and to be able to place it into a phage bank. A higher titer usually means the phage has a higher rate of infection. This is also good to know for phage therapy because it helps determine which phages would be best to use for a bacterial infection, based on their titer.

  2. what are the biological reasons why a phage would undergo a lytic pathway compared to a lysogennic pathway?

    1. Once the DNA is integrated into the host genome, a phage that is undergoing the lysogenic life cycle will represses it’s proteins forming genes (that would usually cause it to form tail and capsid proteins to make more phage) and instead stays fairly harmlessly integrated in the genome. This will occur until host conditions deteriorate, which could be due to pH change or a depletion in nutrients for example, and stop repressing the protein forming genes and begin the lytic life cycle. Once the DNA from a lytic phage is integrated into the host genome, it immediately starts using the host machinery to synthesize proteins. Many lytic phage lack a repressor protein and so it is not able to stay integrated peacefully like a temperate phage. In short, weather a phage undergoes the lytic or lysogenic life cycle depends on it’s genome and what proteins it codes for.

    1. As far as phage therapy goes, each phage has it’s pros and cons. Mini has a higher infection rate as seen my it’s larger plaques and higher titer, however it is a temperate phage which is not typically used for phage therapy. WaltJr is a lytic phage which is good because it can completely kill the bacteria, however it has a lower infection rate. WaltJr also has the advantage of having more results than Mini, at least as far as our research goes.

  3. Which phage, Mini or WaltJr, do you believe would be more beneficial for phage therapy, or would be more worthwhile to pursue research with in that context?

    1. From our research, I believe that Mini would be more beneficial for phage therapy because it has a higher titer as compared to WaltJr and a higher rate of infection as shown by it’s larger plaques. However, Mini is a Temperate phage that undergoes the lysogenic life cycle and so in order to be most beneficial for phage therapy it would need to begin the lytic life cycle to be able to completely kill bacteria. Phage therapy also depends on what bacteria is being treated, and so we would need to do more research on both phage’s bacterial host ranges to be able to say for sure which is best and for which bacteria.

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