By Andrea Uy
I just finished plating a dilution series of my HTL for the fourth time. I’ve made my HTL twice, and created web plates more times than I can count. It’s not due to the clumpy agar or contaminated phage buffer that many of my fellow phage-hunters experienced. No, I had no problems and was actually supposed to be one of the first few to finally see the results of my hardwork using the electron microscope. That was, until my phage decided to perform a magic trick.
This is my phage for the past two months:
This is my phage right before I was going to do my EM:
As you can see, there is a sudden, quite obvious, change in morphology. What is this? Is it contamination? What happened? I’ve never seen these weird plaques until my HTL serial dilution.
At this point, I was pretty depressed. I was really excited to finally see my phage and yet I had to go back a couple steps and work from my MTL. And so I performed a serial dilution using my MTL stock.
Next class, I found that my MTL was clean – they showed the same small, cute, clear plaques! I was thrilled; I didn’t have to go back to streaking. So I plated those and created six web plates from which I drew my new HTL.
While waiting, I decided to replate my old HTL anyway. What’s the harm? Here we go.
Well look at that! My HTL was apparently clean. It might have been some contamination in the top agar or phage buffer. Oh well, guess I won’t need the MTL web plates I created.
Oh how I regretted that.
Since I deemed HTL #1 clean, I performed another set of serial dilutions in order to calculate my titer:
Doesn’t this look familiar? I guess I really did have to make another HTL.
And so I did, using the six web places that I luckily did not toss out. And another series of HTL dilutions began.
Though I did have some top agar issues here, it’s still quite evident that the weird large plaque is back. Why?! My MTL was clean, and I redid my HTL. Where is it from?
Another interesting thing to note is that there is a web plate of the larger plaque at -1, and a web plate of the smaller plaque at -4. It magically transforms once it crosses the -3 to -4 barrier. It’s as if two separate serial dilutions are occurring at once.
I’m not quite sure what’s happening, and why it’s happening, but one thing is for certain: I’ve got myself a magical morphing phage.