Antibacterial Resistance Lab Report

Vu Nguyen BIOL 1003/22 ANTIBIOTIC RESISTANCE LAB REPORT Introduction Natural selection is a non-random process in which individual with favorable traits for the environment will likely survive and reproduce than those without these traits. In contrast to Natural selection, Artificial selection is the process in which desired traits are intentionally chose to breed among individuals. Antibacterial resistance is the process in which strong and highly resistant bacterial is selected against weaker bacterial. The selected bacterial then continue to reproduce and create a stronger bacterial population, which is resistant to antibacterial materials. Antibacterial resistance is the result of natural selection because the bacterial with highly adaptable
After finish placing paper disks, the plates will be closed, sealed and incubated for 24 hours. This is the end of part one. Part two of this experiment dealing with selecting for resistance. This begins with measuring the zone of inhibition, where no bacteria can grow just around the paper disc, of each plate in millimeters to see how resistant the bacteria are. Then the experimenter takes a tube of tryptic soy but no E. Coli and an incubated plate. The tube needs to be correctly labeled with the culture type and the plate number. After that, the bacteria lying along the colonies along the inner edge of the zone of inhibition is selected and taken out using a sterile inoculating loop. With the bacteria on, the sterile inoculating loop will be swirled in the tube of tryptic soy broth. After 30 seconds to a minute, the experimenter discards the inoculating loop and tighten the lid on the loop, leaving a quarter of it loosen, and secure the tube with a small tape. The tube then will be incubated for 24 hours. This is the end of part two. After 24 hours, the experiment is repeated, using the results from the end of the previous part two as the insert for the beginning of the new part one. The independent variable here is the exposure to triclosin or the rounds and the dependent variable is the diameter of the zone of inhibition. Results For the experimental
Through four rounds of this experiment, the strongest bacteria were continuously selected against the weaker ones hence resulted in the size of the zone of inhibition becoming smaller and smaller. For the control group, the size of the zone of inhibition from the beginning had been significantly smaller than that of the experimental group. Throughout the experiment, the zone of inhibition did decrease but just for a relatively small degree. This suggests that the experiment was valid in testing antibiotic resistance. Among the data set, there are some potential outliers. For an item to be considered a potential outlier in this experiment it has to be greater or less than three standard deviations from the mean diameter for each round. In the experimental group, the potential outlier for round 3 is 36 mm and those for round 4 are 25 mm, 27 mm and 27 mm. In the control groups, there is one potential outlier for round 1, which is 20 mm, one potential outlier for round 3, which is 9 mm and two potential outliers for round four, which are 7 mm and 9 mm. The existence of these outliers may due to the experimenters’ not getting the exact bacteria from the edge of the zone of inhibition, closing the lid of the tube too tight so the E. Coli could not fully grow, or difference of the concentration of triclosin in some tubes. However, the number of these potential outliers is relatively insignificant to the