Mystery TSA Plates

Hey guys!

So here's my results from Exercise A: Ubiquity of Microorganisms of Lab #1: Survey of Prokaryotes. The four surfaces I swabbed were my hair, hair tie, house key, and cell phone. Below are photos and data of the growth progression of my plates over the course of a week. 

Figure 1. Photos of plates (upside down) immediately after preparation.

Figure 2. Photos of the room temperature plate and body temperature plate on Day 3 and Day 7.

Table 1: Room Temperature (24°C) Plate Colony Count

DAY	HAIR	CELL PHONE	HOUSE KEY	HAIR TIE
Day 1	0	0	0	0
Day 3	1	1	2	9
Day 7	15	5	7	21

Table 2: Body Temperature (37°C) Plate Colony Count

DAY	HAIR	CELL PHONE	HOUSE KEY	HAIR TIE
Day 1	0	0	0	0
Day 3	315	36	22	332
Day 7	351	38	23	321

Identification 
Both plates contained several organisms which I was able to identify some through the Bacteria in Photos Website. On the body temperature plate, Mycoplasmas has a 'fried- egg' like appearance, Staphylococcus epidermis are white & round, and Staphylococcus aureus are yellow & round. The room temperature plate Pseudomonas and a green mold grew which was not present on the body temperature plate.

Figure 3. Mycoplasmas, Staphylococcus epidermidis, and Staphylococcus aureus are identified on the body temperature plate on Day 7

Figure 4. Pseudomonas (left) and green mold (right) found on the room temperature plate on Day 7.

When I first looked at my plates on Day 3, I was embarrassed that my body temperature plate had already produced an abundance of bacteria in comparison to my lab partners' plates. By then, I had over 300 colonies total and each section had a pretty decent amount whereas my lab partners did not have as much. My room temperature plate on Day 3 was less exciting. It only had 13 colonies so I predicted that there wouldn't be much more growth from there. 

On Day 7, the body temperature plate colonies grew larger as well as a few developed distinguishing features as expected. The room temperature plate developed a cool yellow flower-ish looking bacteria and a green mold which did not appear on the other plate. A few factors may have attributed to this since consistent techniques were applied during preparation. It could be that certain bacteria grow at different rates in various temperatures, contamination, or a combination of both. As far as my microorganism abundance, I believe I chose surfaces that either have a good bacterial flora or that come into contact with it often.

My most shocking result was from my hair tie which I am still wearing today. Since there were different bacteria on each plate indicates that it contains the most diverse microorganisms. Considering what I do with my hair tie, wrapped around my hair, on my wrist, in my bag, and placed on numerous surfaces provides many opportunities to pick up anything its on. While researching human bacterial flora, I came across a CBS News article regarding a woman who gets an infection from a hair tie. Its frightening to think of getting an infection from an everyday item but it has taught me to be more cautious of where I place it.