7/16/12

What have I been doing?

My internship here at Phoenix College for this summer so far has been fun and productive. I have done the “behind the scenes” such as washing and sanitizing the materials that were used in lab experiments. Biohazard items are disposed of in a manner of placing the materials in a biohazard bag, wrapped up, and put into an autoclave. After selecting the setting “BIOWASTE”, and as the time to laps, you will take the autoclaved bag out and put into a biohazard bin.

I have also prepared lab experiments for classes before they entered the class. I would look over the list and already be familiar with the room because prior to grabbing the items, I had to go through every practical to make sure the materials were in the room. I first place various trays on stations and set a napkin on top in case of spilling during the experiments. Then, I walk around the classroom collecting the materials and setting those on the trays. Depending on how many items are on the list, it would typically take me 30-60 minutes to make sure everything is filled, correct, and looks appropriate.

I have helped preserve the bodies in the cadaver lab. The technique to handle this is by spraying the body down with a formaldehyde solution in a spray bottle. Then place a few pieces of cloth on the body, spray, wrap in a bigger piece of cloth, spray, then zip up the body bag and move to the next one unwrapping everything and spraying.

My experiment:

I have started an experiment which involves hydrogen peroxide. My main question was, “how effective of an antiseptic is hydrogen peroxide?” and I also had a sub-question which was, “where does the foaming come from?” I will be exploring these questions and find the answers to them.

 I answered some preliminary questions before I started such as, how does hydrogen peroxide work? This is answered simply by stating, when it is applied to a surface, it reacts quickly and then breaks down into water hydrogen. At the same time free oxygen radicals are released; these create oxidation, a chemical process in which oxygen combines with another substance to break down or change the function of the molecules. Through oxidation, the bacterium decomposes, rendering it harmless.

There was also the question of, why does hydrogen peroxide foam? When catalase comes in contact with hydrogen peroxide, it turns H₂O₂ into H₂O+ O₂. Catalase does this extremely efficiently-up to 200,000 reactions per second. The bubbles you see in the foam are pure oxygen bubbles being created by the catalase. Hydrogen peroxide doesn’t foam in the bottle or on your skin because there is no catalase to help the reason to occur. (How stuff works, 2012)

Is it catalase positive or negative? When performing an experiment, you look for a reaction indicating catalase positive. If so, it is considered Staphylococci and Micrococci. There is also “Listeria, Corynebacterium diphtheria, Burkholderia cepacia, Nocardia, the family of Enterobacteriaceae, Mycobacterium tuberculosis, Aspergillus and Cryptococcus.

After exploring the back history of it, I conducted a procedure in which I included hydrogen peroxide, sterile loops, and TSA plates, samples of dirt, soil, concrete, and blood. I would seclude a section of dirt and squirt about 1TBS of hydrogen peroxide and record observations. Then, I would do the same for soil, concrete, and blood. My findings were that all of them foamed although the soil didn’t foam instantaneously. When taking a sample with the sterile loop onto a TSA plate and incubating for 24 hours at 37°C, I found multiple colonies which I then took a sample of each colony with a sterile loop and transferred to a TSB tube. After letting it settle for 24 hours in a refrigerator, I took a sterile loop and took a sample from that and spread onto a clean TSA plate. We put that into the incubator and checked the next day.

The dirt, soil, blood, and concrete grew fairly well. What I found was all the dirt colonies and soil colonies foamed. 1 of the 3 colonies for concrete did not foam.

Dirt Bacteria Isolated	Catalase (+,-)
Colony 1	Negative
Colony 2	Positive
Colony 3	Negative
Colony 4	Negative

Soil Bacteria Isolated	Catalase (+,-)
Colony 1	Positive
Colony 2	Positive
Colony 3	Negative

Concrete Bacteria Isolated	Catalase (+,-)
Colony 1	Negative
Colony 2	Negative
Colony 3	Positive

Blood Bacteria Isolated	Catalase (+,-)
Colony 1	Positive

My conclusion is that the foaming comes from the blood and cells which contains an enzyme called catalase. Since a cut or scrape contains both blood and damaged cells, there is lots of catalase floating around.