Bye Bye Bacteria
Sunny Wang, Christina Guan
Moscrop Secondary
Floor Location : J 123 B

BYE BYE BACTERIArnrn In a single gram of soil alone, there is a population of 40 million bacterial cells (Wikipedia) which can easily explain the estimated number of over 30 digits worth of bacterial cells currently on Planet Earth (BBC News). As each second passes, this number increases and at the same time, bacteria is killed. A very common species of bacterium in particular, named Escherichia coli is known to be a cause of disease so naturally, it would be helpful to study the relationship between this species of bacterium and how to kill it as well.rnrn In this experiment, both substances and cleaners were tested to be able to build our knowledge on the relationships between them and E. coli. The experiment had a total of two different parts, but both followed a similar procedure. rnrn A total of four substances and four cleaners were tested: salt, sugar, spirulina tablets, vitamin C, anti-bacterial soap, bleach, vinegar and alcohol. The procedure that was followed utilized prepared agar plates, E. coli bacteria, sterile swabs and an incubator. For the first part of the experiment, substances were mixed into nutrient agar and poured into plates. E. coli was then spread evenly on each plate, incubated and observed. What ended up happening was most substances had killed the bacteria and upon realizing this, further tests were conducted to measure the zones of inhibition that each substance produced.rnrn The second part of the experiment involved measuring the zones of inhibition made by certain cleaners. Sterile paper disks were soaked in each individual cleaner and then placed into the center of an already streaked agar plate which was then incubated. After 24 hours and 48 hours, zones of inhibition became apparent and were then measured.rnrn The results of these experiments had shown that most of the substances that were tested had killed the bacteria instead of helping it grow as previously predicted. Sugar however, did in fact help the growth of bacteria and the colonies were very evident, even matching those of the control. From the further tests conducted, it was found that although most cleaners had killed the bacteria during previous tests, they were not strong enough to provide evident zones of inhibition. In the cleaners section however, throughout all the tests, bleach was consistently the most effective bacteria killer supporting the hypothesis. rnrn In conclusion, this experiment provided many different learning possibilities and expect some more tests to be conducted in time for the Greater Vancouver Regional Science Fair!rn