Day 1 (5/14)

Inoculation of Bacteria from a Cell Phone to an Agar Plate 

Our hypothesis was that cell phones contain a lot of bacteria due to constant use.  A person uses  their cell phone several times a day with infected hands.  We first thought of testing for bacteria when a student in the lab asked if we should sterilize our phone before bringing into the lab.  Since the answer was we decided to test the bacteria to see how much a contaminated phone could possibly contaminate a work place.

The materials we used were:

Ben's unsanitized cell phone

sterile cotton swap

broth in a tube

Petri agar plate

China marker

Materials

In our experiment, because the cell phone is a dry surface we used the broth and first dipped the sterile cotton  swap into the broth.  

Collecting Bacteria!!

Sterile Broth Tube

After swiping it over the keypad of Ben's phone we swiped the cotton swap over the Petri plate several times, with quarter turns.

 After labeling the Petri plate with a China marker we placed it in the 24 degrees Celsius incubator, because the bacteria existed on the phone at room temperature.  Putting in the 37 degrees Celsius incubator could have killed the bacteria due to the higher temperature.

Now we will wait for tomorrow to see how much bacteria is on Ben's phone.

Viewing China Marker under a Compound Microscope

Next, we marked a slide with a China Marker and viewed it under a Compound Microscope

In this experiment we compared the resolution without and then with the use of immersion oil.

Our materials were:

Compound Microscope

China Marker

Glass slide

Immersion oil

After adjusting the compound microscope to 400x magnification the picture was detailed.  But after adding Immersion oil more details were visible and it looked like this:

(thank you Dr. Pathakumuri for showing us how to take a picture of the microscope specimen)

Why was the picture more detailed with the oil?  As learned in lecture today the compound microscope uses one light.  Unfortunately the light may bend in the air before it hits the objective lens.  When we put the oil over the maker it kept the light from bending and allowed more light and therefore more detail. Oil acts like this because it has the same refractive index as the glass.  A refractive index is the light bending ability of a medium.

Inoculation of an Unknown Bacteria using the Antiseptic Technique

We were group 5 and the unknown bacteria that we received was labeled "N" and grows at 30 degrees Celsius.  Our task in the experiment is to inoculate the bacteria.  Our speculation on this bacteria is that it does not thrive at normal room temperature (24 degrees Celsius) nor human body temperature (37 degrees Celsius) 

Our materials:

Petri plate

Bunsen burner

2 slant agar tubes

1 slant tube with unknown "N" bacteria

1 tube of broth

2 inoculators (1 loop, 1 stab)

China Marker

Using the Antiseptic technique we first transferred the "N" bacteria to the 2 slant agar tubes.  After sterilizing the loop inoculator with the Bunsen bur, we rubbed the loop across the gelatin surface of the slant tube containing "N" bacteria we placed the inoculator in the sterile agar slant tube. (we also used the stab inoculator and made three deep stabs into the "N" bacteria and the sterile agar slant tube)

Next we used a sterilized loop inoculator to inoculate the broth sample with the "N" bacteria.

Finally, we used a sterilize loop inoculator to inoculate the Petri agar plate with the "N" bacteria.  To spread the bacteria the inoculating loop was swiped over the four quadrants of the agar plate, between the four swipes the loop was sterilized with the Bunsen burner. During this the lid of the gar plate was kept slightly over the plate to prevent contamination.

After marking the 2 slant tubes, the broth tube and the Petri plate "N" with the China marker, the four samples were place din the 30 degrees Celsius incubator to enable growth

Now we shall wait for tomorrow to see how our bacteria will colonize.  Because we used the antiseptic technique the colonies of bacteria that will grow will be pure colonies, meaning only one bacteria will be on the inoculated samples.

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