SBI3U
Name: _________________
Culturing Resistant Bacteria
Partner: _________________
Purpose: To assess the effectiveness of an antibacterial product in the location it is most likely used.
Method:
1.
In advance of the lab day, choose an antibacterial product (disinfectants (rubbing alcohol, hydrogen
peroxide, hand sanitizer, mouthwash, vinegar) or antiseptics (bleach, Pine sol etc.)) with a specific
locational use and bring to class.
2.
Using a wax pencil or marker, mark two agar filled petri dishes as “controlled” and “experimental”
including your names.
3.
As instructed by your teacher, swab an area of the school (related to the antibacterial product
chosen) that you believe contains bacteria.
4.
Transfer swabs to each petri dish using the method outlined by the teacher. Tape the petri dish lids
as instructed and incubate them upside down in the incubator.
4.
Discard all swabs and wash your hands.
5.
Record the results each day (excluding weekends) in the observation chart you created for 5 days
Observations:
observe and record as outlined in method.
1. Make a chart with date, petri dish type, location & description of bacteria.
2. The description of bacteria should include the following terms.
Description of
Colony
Shape
Margin (edges)
Surface Texture
Colour
Type
punctiform (pinpoint), round,
filamentous, irregular
smooth, curled, wavy, lobate,
filamentous
smooth, concentric, wrinkled,
contoured, rough, shiny, dull, wet,
dry
green, grey, orange, red, yellow etc.
3. Do not confuse bacteria with mold or fungi (these will be fuzzy and have dark colours).
4. Sketch the appearance of your dishes, showing the relative sizes and position of the colonies on each
Petri dish for your controlled and manipulated/experimental dishes. See Example attached for how to
do this. You must include biological diagrams from day 1 of the experiment and day 5.
Analysis:
1. Were you able to grow antibiotic resistant bacteria? How do you know?
2. Confer with classmates to determine which areas around the school appeared to have the most
bacteria? The least bacteria? Suggest reasons for these findings.
3. Which petri dish did you use to make this comparison in question 2? Why?
4. Describe the conditions necessary for bacterial growth.
5. Describe two factors that might inhibit bacterial growth.
6. Explain why it is necessary to have a control in an experiment such as this.
7. List and explain all of the control variables in this experiment.
8. You were in charge of cleaning up the kitchen. One bacterium was left on the counter surrounded
by morsels of food. Under favourable conditions, bacteria may reproduce once every 20 minutes.
At this rate, how many bacteria could be produced from this single bacterium in 6 hours? Show
your calculations.
9. How did you measure the effectiveness of each antibiotic or disinfectant?
10. Was your antibacterial product effective? Inconclusive? Ineffective? Explain.
11. Why is it important for a physician to know the exact identity of the bacteria involved in an
infection?
Error Analysis
Refer to “The Perfect Lab”
Conclusion
Write a comprehensive conclusion according to “The Perfect Lab Report”.
Sample Observations:
Day 1
Control
Manipulated