Bacteria are way cool and super abundant, so for this experiment - wherein we swab location and grow the sample bacteria on TSA plates - I decided to choose a habitat close to home. (It's me) My sampling was kinda jewelry themed, taking samples from the following places:
| Sample | Origin |
|---|---|
| 1 | Dice Necklace (Dice itself) |
| 2 | Jessica's wedding ring |
| 3 | Underside of Fitbit |
| 4 | Earrings |
The samples were swabbed onto two fresh TSA plates; One plate incubated at 37°C to provide a warm environment and another plate incubated at room temperature. Each sample had it's own quarter of the plate. Here's a pic of the initial plates post-swabbing (not that you can tell):
Riveting.
We left the little guys to get it on for two days and wouldya know it, some growth actually showed on one of the samples, so I didn't have to cry!!!
There was a lawn of growth present on sample 4B, the sample taken from my earrings and incubated at 37°C. I would have done a colony count here, but the colonies individually appeared very small and numbered >350 easily so I feel it was fair to just note the appearance and abundance of the colonies. There were also 2-3 colonies on sample 1 at 37°C and sample 3 incubated at both temperatures. These were again rather small at the time.
All the colonies had the same apparent morphology - small, circular, flat, off-white with entire margins.
Naturally the next step was re-incubate and do nothing for another 5 days while they really settled down so that we could get a proper look at what was going on.
BAM. Bacteria just got real. The lawn on 4 at 37°C was becoming steadily denser, but additionally, one managed to just pop up on 4 at room temperature out of nowhere I guess, like the kind of surprise birthday party that makes you drop you groceries everywhere and whip out a microscope. It was a prolific lawn of small colonies between larger colonies so I didn't bother to do a colony count again.
Additionally of note are the impressive amount of growth the isolated colonies went through on 3 at both temps and 1 at 37°C. They were barely specks on Day 2 but were sizable at the end of the experiment, possibly due to the massive amount of nutrient hoarding you get to do as an isolated colony.
Overall
Needless to say, sample 4 was most bacteria abundant. The room temperature plate likely took longer to grow since the plate at 37°C is a more optimal environment for the bacteria to grow. I'm unsure if the colonies on 1 and 3 were a result of bacteria on the sample or cross contamination from the bacteria on 4. I'm pretty sure it's the samples themselves but the colony count is kind of sparse to be sure. Also questionable is the appearance of colonies on sample 1 at 37°C but not at room temperature. Normally this might indicate bacteria that can only survive at 37°C on the sample, but the bacteria seem the same as those growing on the rest of the plates which appear on both plates. Perhaps this is instead due to uneven sampling. Jessica's ring is the only thing not bacteria scathed. Feel free to give her a high-five because her hands are spotless. 👍
Using this guide to determine what kind of bacteria was growing on my plate, my best guess as to the identity of the bacteria is Staphylococcus epidermidis.
Staphylococcus epidermis is actually pretty normal and considered part of your standard skin flora. It's also not really pathogenic unless your immune system is already compromised. Which is neat! And also makes me feel much more comfortable putting my earrings back on.
Hey Yasmin! I thought that your post was very amusing. I liked the inclusion of the blog and how your style of writing was more chill instead of the blog post being super serious. I think it's very surprising that the earrings had the most growth of bacteria instead of something like a necklace or a fitbit, which I am not even sure how one goes about washing this kind of contraption. I'm also quite surprised that your other sections on your TSA plate had little to no growth throughout the experiment. Do you think that there was no bacteria growth on the ring because Jessica washes her hands often or because she washes her ring regularly? (Unless she doesn't do both of those things (jk))
ReplyDeleteHey Yasmin, I thought you post was... riveting (minus the sass). Your four choices are interesting since they are things you wear everyday. It made me wish I could've sampled something I wear everyday as well. Your earring growth was pretty crazy, but makes some sense. Since the earrings go through your earlobe, the closed off environment would likely host some bacteria. Your identification of it seems spot on because Staphylococcus epidermis would live on the skin I would assume according to the name. It was cool to see the tiny specks on samples 1 and 3 grow super large by day 7. One of my samples did the same. I wonder how big they would get to be if we continued to incubate them for a couple more days.
ReplyDeleteHi Yasmin, I found your choices of places to test very interesting. You chose all things that we wear near our body somehow. I also chose for my plate to swab around my earrings and got similar results. It makes sense that the room temperature plate did not grow bacteria as quickly considering that it is the temperature we are usually in and don't have bacteria just coming off our ears...hopefully. The identification of the bacteria that you made seems to make sense as that earrings have to be clean regularly because they grow stuff so quickly, so it makes sense that it is something that we would regularly find on our skin and wouldn't really hurt us. I wonder if there is any thing the bacteria does for body, in return for us hosting it? Great job, Yasmin!
ReplyDelete