don't use the sink in the back anymore

Day 1:

Day 3:

Day 7:

Sample A: Front of the room cold water sink handle

Sample B: Front of the room hot water sink handle

Sample C: Back of the room cold water sink handle

Sample D: Back of the room hot water sink handle

Questions:

• What objects did you decide to sample and why?

I decided to sample the sink handles for hot and cold on the front and back sinks. I wanted to see if there was a difference in the amount of microbes between the different temperature handles on the sink and also the location of the sink.

• What type of growth did you see on Day 3? on Day 7? Describe the growth.

On day 3, there were just 3 small white colonies and 5 tiny white colonies on sample C, which is the back sink cold water handle. I could also start to see some tiny colonies start to grow on samples B and D (both of the hot water sink handles) when I looked really close, but those were even smaller than the smallest colonies on sample C. The cold water sink handle in the front of the room sample was pretty barren on day 3.

• Did you have growth from all the samples? If not, why do you think that happened?

In the end, all the samples had growth.

• What sample yielded the most growth of organisms? Why do you think that happened?

On both day 3 and 7, sample C had the most growth. I want to say that this is because hot water kills bacteria but I heard that the temperature the water needs to be at to actually kill bacteria is way hotter than you think and we usually don't wash our hands with water that is hot enough. I noticed that the front sink had two containers of soap and it made me think that the front of the room got restocked and cared for more because it gets more traffic, so maybe the front sink gets cleaned more?

• Did anything about the growth you observed surprise you?

Yes. The front of the room sink grew less bacteria on both handles than the back. I expected for it to grow more bacteria because it's the more commonly used sink in my opinion.

• Describe the plate of your lab mate. What did you notice about their plate?

My lab mate was Horea Oprean. On his sample, i noticed that the toilet seat was full of bacteria, while everything else didn’t grow bacteria.

• Compare and contrast your plate with your lab mate's plate.

The toilet seat is much dirtier than the sink handles around the room as expected, but they all grew bacteria. I’m surprised that they keyboard, doorknob and phone screen didn’t grow bacteria at all, while the sink handles did. You would think that the sink handles would be devoid of bacteria because people have just washed their hands, but I guess it stays from when the person has to turn on the sink to use it. I really thought that the keyboard would have bacteria though.

• Reflection: What does this mini experiment reveal to you about the ubiquity of microorganisms?

From my experiment, I wanted to say that bacteria was more common than you think, but after seeing and comparing mine to Horea’s experiment, I have to settle on bacteria being selectively ubiquities. The keyboard sample is the most confusing to me.

• Write at least 3 scientific questions based on your observation.

1. Does the spot on the keyboard matter when growing bacteria?
2. How do the sink handles in the restroom compare to the toilet or the sink handles in the lab room?
3. Is there a way to take a precaution that doesn’t allow the growth of bacteria on a specific surface, even after people interact with it?

• Write 1 hypothesis based on the questions above.

The sink handles in the restroom would be the dirtiest surface out of those three because people finish up at the toilet and then move to the sink handles, which we know holds onto a lot of bacteria.