We made the plates on Monday, 4/4/16, and on Wednesday, 4/6/16, the two plates looked like this: \
The plate on the left is the one incubated at 37 degrees Celsius, and the one o the right was incubated at 24 degrees Celsius. On the left plate, it is seen that the keyboard has the most colonies of bacteria, with the doorknob having around two colonies and the table having one visible colony. In the plate on the right, there is only one colony visible in the keyboard portion.
After a week of incubating, on Monday, 4/11/16, the plates looked like this:
The left plate was incubated at 37 degrees Celsius, and the right plate was incubated at 24 degrees Celsius. Comparing these dishes to the dishes on Wednesday, there were definitely more bacteria on on these dishes, especially on the left plate. Different types of colonies can also be seen, and overall I counted 15 colonies on the left plate, and five colonies on the right plate.
The keyboard had the most number of colonies, which made sense since it was being used by different people every day. The doorknob and table were the same case, so bacterial growth on these portions was expected. One thing that did surprise me, however, was how much of a difference temperature made on the bacterial growth of the two plates! I didn't expect it to be that much of a difference, but it turned out to triple the amount of visible colonies, which was quite interesting to me.
I examined the left plate under a microscope to see what the colonies might look like, and here is what I saw under a section of the keyboard portion:
I noticed two different colonies: the three white circular ones with orange centers, and the brown one at the bottom, which is out of the field of view.
In the end, this experiment showed me how bacteria can be found everywhere! People say this all the time, but this experiment just proved that statement. This also showed me how temperature can drastically affect bacterial growth, and it also introduced me to the TSA dish, which I never used before to grow bacteria.
Hi Patrick,
ReplyDeleteI heard that keyboards contain more bacteria than toilets which is very gross. Otherwise, I know that your "three white circular ones with orange centers" are a Mycoplasmas bacterial species. One of their distinguishing characteristics is that they look like a fried egg and yours sure does. I had a couple on one of my plates.
Hello, Patrick!
ReplyDeleteYes, I too was surprised by how much bacteria was in my sample. Although my cultures did not grow to your extent, I did take note on the temperature changes as you did. I can see that temperature had a profound impact on your bacteria’s ability to grow and thrive as well. Knowing that most of your bacterial growth came from a keyboard frightens me since I often use the college computers for school work. Being the germophobic person I am, that is quite unsettling! Nevertheless, I would expect that your colonies would have grown as you witnessed: with the keyboard having the most, followed by the doorknob, and finally the table. To me, this seems like the bacterial growth with the highest population corresponds to surfaces with the most human interaction and lowers accordingly with decreasing human interaction. Nice observations!
Hi Patrick,
ReplyDeleteAlthough I was not as surprised with the amount of bacteria that was seen in your culture, I was surprised by the diversity. It was interesting how in one culture, you had a lawn of bacteria, and different types of bacterial colonies. Personally, I tested a lab table too, but I did not observe near the growth which you did. I saw only one small colony, while yours appears to have two colonies of different types of bacteria. Stacie mentioned that some of your bacteria may be Mycoplasmas, and that is very interesting.
I loved the pictures of the development of the bacteria over time!