1. Bailey McCue Grade 9 Academy of Notre Dame de Namur

2.  The purpose of this experiment was to find the weakest solution of bleach in water that would effectively kill E. Coli and B. Cereus bacteria.

3. Escherichia ColiBacillus Cereus  Gram negative  Rod shaped facultative anaerobe  Found in small intestines.  Gram positive 10% bleach in water solution is sufficient to kill most bacteria.

4.  If different bleach solutions are tested on bacteria, then the weakest solution of bleach in water that will effectively kill bacteria will be found.

5.  Escherichia Coli bacteria  Bacillus Cereus bacteria  Bleach  Water  16 agar plates  48 sterile discs  Inoculating Loop  Forceps  Ruler  Marker  Tape

6.  1. Prepare solutions of 0.5%, 1%, 3%, 5%, 8%, 10%, and 15% bleach in water.  2. Label each of the agar plates with the solution and the bacteria to be tested.  3. Inoculate 8 plates with E. Coli and 8 plates B. Cereus using the inoculating loop.  4. Hold a single sterile disc with the forceps, dip it into a bleach solution, then place it in corresponding agar plate. Do this three times for each bleach solution.  5. Place all plates in an incubator and allow to incubate over night.  6. Examine all plates and using a ruler with mm, measure the zones of inhibition.  7. Safely dispose of all plates.

7.  The independent variable is the strength of the bleach solution used. (bacteria?)  The dependent variable is the amount of bacteria killed.  The constants are the amount of bacteria, amount of solution applied to each sample, temperature, time, type of bacteria and type of bleach.  The controls were the agar plates with the sterile discs soaked in water

9.  The results of this experiment supported my hypothesis that the if different bleach solutions are tested on bacteria, then the weakest solution of bleach in water that will effectively kill bacteria will be found.  The weakest solution of bleach in water to effectively kill bacteria was the 3% solution. Anything below this solution was ineffective.

10.  Thank you for listening to my presentation. Are there any question?