Bacteria Science Fair Experiment on Bacteria & Antiseptics

Using Bleach

PROCEDURES

1. First gather the bacteria.
a. Escherichia coli
b. Staphylococcus Aureis
c. Pseudomonas Aerugines
d. Staphylococcus Epidermidis
2. Then gather the antiseptics.
a. Chlorine Bleach
b. Alcohol (Isopropyl) 70%
c. Proidone Iodine 10%
d. Chlorhexidine 4%
e. Control- saline solution 0. 45%
3. Next punch tiny discs out of filter paper. Five discs for each antiseptic.
4. Soak the discs in the antiseptic solution
a. Each disc 20 Micro liters
5. Then check the density of solution with bacteria. Density has to be 15%. Use a colorimeter to find 15%. Swab the bacteria on blood agar plates.
6. Next place the discs on the blood agar plate.
a. Make sure discs are pretty far apart.
7. Leave blood agar plates in an incubator for 24-48 hours.
8. After the time check the plates and measure the diameter of the zone if death using a caliper. Write down your result.
9. Destroy the remaining bacteria with an autoclave using the hospital’s procedures.

RESULTS

The original purpose of this experiment was to determine the effect of different antiseptics on the survival rate of bacteria.

The results of the experiment were that Clorox bleach did the best and had the biggest zone of death, for every bacteria type, averaging 46mm. in diameter. Chlorhexidine 4% did the second best overall and had a zone of death, averaging 27mm. Proidone Iodine 10% had a smaller zone of death, 16. 5 on average. Control-saline solution 0. 45% only worked on Staphyloccus Epidermidisso the average was less than 4mm. Alcohol (Isopropyl) 70% did the worst and did not kill any bacteria.

CONCLUSION

My hypothesis was that Clorox bleach would kill the most bacteria.

The results indicate that this hypothesis should be accepted, because for every type of bacteria, bleach had by far the largest zone of death.

Because of the results of this experiment, I wonder if other types of bacteria were tested would bleach still do the best. Maybe if I had used other antiseptics, bleach might not have been the best.

If I were to conduct this project again I would have done my experiment twice or three times instead of once to make sure my results were constant. It was surprising that saline killed any bacteria at all. It was also unexpected for isopropyl alcohol to be completely ineffective. More trials might help clear this up. 3rd party contributor