Ms. Graham
Period 3 Biology H
February 27th 2015
Bionic Antibiotics VS. Bacteria
Abstract:
The bacteria lab preformed in class tested the effectiveness of antibiotics against bacteria. During the lab we tested the antibiotics penicillin, streptomycin and tetracycline against the bacteria Escherichia coli and Staphylococcus epidermis in order to determine which antibiotics fought which bacteria most successfully. In order to monitor the experiment, we kept a control sample in which no bacteria was present, only an antibiotic disk. After incubating the bacteria with the antibiotics, we measured the zone of inhibition. The zone of inhibition is the clear ring that is left around a tablet of antibiotic in which little to no …show more content…
Next, on the lid of each plate, you should draw four equal quadrants and label them c (control), 1, 2 and 3, as in the example photo below. Be sure to make note of which antibiotic 1, 2 and 3 correspond with before moving on and repeating these steps on the second agar dish. Following this, on the side of each agar plate, make a label indicting your teacher name, period number, lab group and bacteria sample, this will allow you to stay organized throughout the …show more content…
After measuring the zone of inhibition, or area where bacteria did not grow enough to be visible, we found that the antibiotic penicillin was unsuccessful in killing both E.coli and Staph.edpidermis, as the zone of inhibition left in both bacteria was a number not even reaching 2. Another tested antibiotic, Streptomycin, created an average zone of inhibition of 4.1 millimeters in the E.coli bacteria, this tells us that it was somewhat effective as it left a good sized area of the plate free of bacteria. When this same antibiotic was tested against Staph.epidermis, the average zone of inhibition was 5.0 mm, showing us that streptomycin was effective in combating this bacteria. When the third antibiotic tetracycline was tested, the average zone of inhibition left in the E.coli bacteria was 8.2, which means that tetracycline was effective against the E.coli. However, when tested against Staph.epidermis, the average zone of inhibition left behind was only 1.1, allowing us to conclude that tetracycline was not able to successfully kill this