By Jessica Bauer
Going into lab last week I was thrilled to check on my plates and see how my little phages were doing. I had just done my Phage Titer Assay test and found that my -1 dilution had a beautiful arrangement of mostly plaques with some M. smegmatis found in between them. The class before, I had made Medium-Titer-Lysate from my beautiful plate and had plated my dilutions up to the -7. That day going into lab, I was excited to see my results and get started on harvesting more and more of my plaques. Unfortunately, that excitement soon diminished.
As soon as I saw my plates I knew something was wrong. My plaques were clear and small, yet the plaques found on my 0 dilution, pure MTL, were odd looking. There was larger cloudy ones and then also a whole group of small cloudy ones around the outside of the plate. What was going on? As I looked at my further dilutions the mystery continued. The -1, -2, and -3 dilutions all had this strange flowery look to them. They looked nothing like the small, clear plaques I was used to seeing. Also, as I opened my plate I was met with a shine that I knew could not be from the normal M. smegmatis. As I moved on to the -4 and -5 plates I was happy to finally see my small, clear plaques coming back, but unfortunately there was not nearly enough to have a perfect web and move on in lab.
I decided I had to try and get rid of this strange substance. So, I filtered my MTL solution again with a filter and syringe, I got new top agar and new phage buffer and made sure I stayed closer to the bunsen burner then ever before. I plated my dilutions again and thought I had gotten rid of this contamination menace for good. Sadly I was wrong.
The next day in lab upon examining my plates, I found the same thing. The smaller dilutions were covered in this flowery substance and obstructing the view of my plaques and M. smeg. What could it be this time? I had no idea. Again, I filtered the MTL and used new phage buffer and top agar. I even went as far as to wipe down all the micropippetters with ethanol and made sure to use sterile pipettes when taking liquid out of larger tubes. I plated my dilutions for a third time and left lab feeling confident that this time I would be rid of this contamination for good.
I was wrong. My third round of dilutions were infected with this contamination just like the first. At his point I was done, there was nothing more I could do. This contamination had ruined my wonderful plaques and MTL solution. All I could do was throw it all away, along with my hopes of finishing early, and start all the way back from performing the Phage Titer Assay test with a new plaque.
I never found out how this dreaded contamination got into my plaques and destroyed all my progress. It will always be a mystery. I just hope that it does not happen to anyone else, because this contamination is a menace. If by chance it does happen, good luck getting rid of it, it likes to stick around for good.