By Matt Merola
I had just waited thirty long minutes. Finally, my MTL (medium titer lysate) was ready to be extracted after I flooded my plate with phage buffer and let it sit. Looking around I was about a step ahead of everyone else, and felt I was in a great position and would possibly be one of the first people to actually get to view my phage. Things were going great. After putting the MTL into a 15 mL tube, I just needed a very small amount so that I could dilute it with Phage Buffer. I left the lab that day feeling even better than when I walked in, and was on a great track.
Then the next lab day it happened. Contamination. I was ecstatic. Thrilled. Definitely one of the best results I have gotten from day 1. All sarcasm aside, this obviously means I would have to repeat my last step, but no big deal. How contamination happened was the big question. After some thought and looking through my lab notebook, I realized that in order to extract some of my MTL for dilution, I stuck a micropipette into the 15mL tube. The whole micropipette. Not one of the smartest moves I have made. The amount of times that pipette was touched by my gloves definitely would contaminate the micropipette, and when it hit the sides of the tube while I was extracting the MTL the whole tube could have gotten contaminated.
But as the saying goes “there is no use crying over spilt milk.” Instead of getting upset, I had to learn from my mistake. First, Dr. Fisher gave me some great advice that I should wipe down the micropipette with ethanol alcohol before use, to minimize the chance of contamination in general. This is one technique I have done ever since. I also decided that I should transfer liquids out of the larger tubes (such as the 15 mL one holding the MTL) with the larger, clean pipette fresh out of the wrapper and use the micropipette only when extracting from microcentrifuge tubes (maybe should have realized this a little earlier). While it may take a few more seconds transferring the MTL from the 15 mL tube into a microcentrifuge tube and then from that microcentrifuge tube into another microcentrifuge tube, it would minimize any chance of contamination. With every mistake comes a chance to learn, and this is one mistake I will not forget.