By: Sierra Toll
Title: The effects of antibiotics on the growth of Escherichia Coli Problem: How do antibiotics affect the growth of E coli?
Hypothesis: If Penicillin is applied to the bacteria, then the zone of inhibition will be larger. Background: The purpose of this lab was to see how effective a certain antibiotic is to kill E coli. The lab tested three antibiotics, Penicillin, Erythromycin, and Neomycin. The zone of inhibition, which is the amount of space the antibiotic kills in certain amount of time, determined how effective the antibiotic was on that certain bacteria. Control: Quadrant 4 with no antibiotic
Constants: Temperature, bacteria, Petri dish, agar, nutrient broth, time Manipulating Variable: Antibiotics (Penicillin, Neomycin, Erythromycin) Responding Variable: Zone of inhibition
* Petri dish
* Nutrient broth
* Cotton swab
* 37 degree Celsius incubator
* Permanent marker
1. Gather supplies
2. Make lines on the back of the Petri dish separating them into 4 equal quadrants 3. Swab Petri dish using Q tip with E coli all over
4. Place Penicillin on the 1st quadrant in the middle
5. Place Neomycin on the 2nd quadrant in the middle
6. Place erythromycin on the 3rd quadrant in the middle
7. Lift the Petri dish upside down to test if the antibiotics will stick to the bacteria 8. Close and tape the Petri dish
9. Let the dish sit upside down for 24 or 72 hours
Data: The Penicillin had little dots of colonies. They were bacteria wanting to re grow in the zone of inhibition. Penicillin was the 2nd most effective. All the zone of inhibitions looked pretty clear besides the growing colonies. Neomycin had the smallest zone of inhibition, Erythromycin had the largest!
Effect of antibiotics on the growth of E coli
Manipulating Variable| Responding Variable| Qualitative data| | 24 hours |...