Hi Everyone,
In the lovely picture above, I compare suspended bacteria to a "standard" called 0.5 McFarland standard. It's supposed to help guestimate the amount of colony-forming bacteria per milliliter. IT HAS BEEN A SIGNIFICANT PAIN IN THE BEHIND. First, it took a lot of work to understand exactly what the McFarland standard was. Josh and I tried ignoring it (1. because we didn't have it, 2. because what is it?), but it kept popping up in the research articles I had been reading. Eventually, we decided to ask our nearest microbiologist, Dr. Robinson. Turns out she also had no idea what this "standard" was. So we had it ordered, just to see that it's a little tube and card (smh). I don't think it made a significant difference in my research. However, for the purpose of science, it was nice to have. Based on the standard, there is around 5x10^5 colony forming units/ml in the bacteria tube.
On Tuesday, I plated E. Coli and tested the effectiveness of 4 samples to kill the bacteria. The sample included , Aloe Vera gel (store bought), Windex, Tap water, and 70% Isopropyl Alcohol. This experiment was pretty much used to keep me busy as I haven't yet been able to start a project. However when I came in Wednesday, I found some interesting results. The zone of inhibition was basically 0 for every sample, including the isopropyl alcohol. Although the tap water, being the control, and the Windex doesn't jump out as a surprise to me, the 70% Alcohol does. Originally I had two hypothesis's on why this occurred. One being that because E. Coli is a gut bacteria and therefore is built to withstand alcohol. The second theory suggest user error such as the letting the alcohol evaporate to much before I was able to put the disk on the plate. Because of the results on Wednesday and with the first hypothesis in mind, I chose to do another plate instead with Staphylococcus. I ch...
Comments
Post a Comment