1. Testing the effects of various disinfectants on the growth of E. coli
Pam Stewart

2. objectives
Compare the effects of different products that claim to kill bacteria
Design a controlled experiment
Plan a methodology using appropriate tools to gather precise and accurate data
Determine if data obtained was valid and reliable
Compose and defend a conclusion based on data obtained from a controlled experiment
Publish results of a controlled experiment
Learn sterile handling techniques for bacteria growth
Successful cultivation of bacteria

3. Previous Learning
Students will apply previous learning to design and complete the experiment
Scientific Method
Graphing

4. Journaling for a lab
Research question / Purpose
Background
Independent variable
Dependent Variable
Hypothesis
Create the following sections w/ notes for tomorrow’s lab:

5. Observation
Everyone in the family contracts severe food – poisoning one night after dinner.

6. First Question What caused it?
Mom remembers cutting up the raw beef on the same cutting board she chopped vegetables on.
She only rinsed the cutting board with water between uses

7. Research Question Research Purpose
Which product is best to clean/sanitize the cutting board?
Determine the best product to eliminate the E. coli from the cutting board
Research Purpose

8. background
E. coli is most commonly found in the intestines of humans and other warm- blooded animals
Transmitted most through raw/uncooked meat and surfaces
Prokaryote: one-celled organism w/ no nucleus

9. Background research They live in mixed populations almost everywhere.
Observing one isolated bacterial specimen not contaminated with other microorganisms is not representative of the real world

10. What does e. coli look like growing on nutrient agar?

11. What will it look like if the product is effective?
Zone of Inhibition

12. Design a controlled experiment
Independent variable
Dependent variable
The various products that claim to kill bacteria (E. coli)
The growth of E. coli – determined by measuring the zone of inhibition around each product disk

13. Ammonia based products
Bleach
kills some of the most dangerous bacteria,  including staphylococcus, streptococcus, E. coli and salmonella – as well as viruses like the flu and the common cold. Harmful to respiratory tract and should only be used in a diluted form
Soap
There is a common misconception that antibacterial soap, in particular, is effective in eradicating all germs. Although antibacterial soap may kill some bacteria, it is no more effective in doing so than regular soap, and does nothing to fight viruses like colds or the flu.
Anything w/ triclosan
Cleans no better than regular soap but has been found to be disruptive to human endocrine system
Ammonia based products
Although it may be a more eco-friendly cleaning solution than chemical-based products,  ammonia is not registered as a disinfectant by the Environmental Protection Agency (EPA). Although ammonia might kill salmonella and E. coli, it is not an effective defense against dangerous staphylococcus bacteria.
Alcohol-based sanitizers
 claim to prevent infection from MRSA, salmonella, E. coli, the flu, or other bacteria and viruses, but the claims aren’t supported by the FDA. The Centers for Disease Control and Prevention (CDC) also warns that these products are largely ineffective against the norovirus. Some hand sanitizers may also contain triclosan.
vinegar
does not kill dangerous bacteria like staphylococcus.
Baking soda
ineffective against most bacteria, including salmonella, E. coli. and staphylococcus. 

14. Choose 6
With your table group, determine which products you wish to test.
We will vote and determine which 6 we wish to test

15. Hypothesis
Write your group’s hypothesis

16. Constants / Controlled variables
What do we need to keep consistent to prevent confounding variables?
Type of agar
Same strain of E. coli
Test same products
Same growth time
Same methodology

17. Day 2 – Lab day bell work Prepare yourselves to conduct a lab
Hair pulled back
No loose or dangling clothing / jewelry
Pants
Closed toe shoes

18. objectives
Compare the effects of different products that claim to kill bacteria
Design a controlled experiment
Plan a methodology using appropriate tools to gather precise and accurate data
Determine if data obtained was valid and reliable
Compose and defend a conclusion based on data obtained from a controlled experiment
Publish results of a controlled experiment
Learn sterile handling techniques for bacteria growth
Successful cultivation of bacteria

19. Materials Manager: 1 – agar plate 1 – sterile disposable pipet
1 – sterile swab
1 – paper towel
1 - Box of paper disks (to soak w/ products)
1 – disinfecting wipe (to clean lab table)
1 – forceps
1 - sharpie

20. Lab Technician Get on a pair of gloves *
Obtain 1 – small yellow tube (E. coli)
* Only the lab tech needs to wear gloves

21. Always label an agar plate on the bottom of the plate!
Recorder - procedures
Always label an agar plate on the bottom of the plate!
Label the plate with your lab group’s period number and lab table number
Example: period 1, lab table 3 = 1 – 3

22. Recorder - procedures
Draw 6 small circles, evenly spaced and label them with a number (1 – 6)
Create a drawing in your lab book to represent your agar plate and label the circles the same as you did on the plate 1 2 6 5 3 4

23. Recorder - procedures Product numbers: 409 Lysol spray
Toilet bowl cleaner
vinegar
Hand sanitizer
Wet wipes

24. Quality Control - Procedures
Today’s goal is to avoid contamination!
Sanitize work station before beginning lab
Only open the agar plate lid & yellow tube lid enough to do the required procedures, then immediately close it back
Do not place agar plate lid onto desktop = contamination
Dispose of pipet and swabs in the green bucket on front lab desk

25. Lab Tech - procedures
Using sterile pipet, transfer .25 mL from the E.coli broth tube onto the agar plate
Using sterile transfer swab, spread e. coli broth evenly onto the plate surface
Do this gently so as not to puncture the agar surface

26. Lab Tech - procedures
Using forceps, dip one piece of hole-punched paper into the product solutions being tested
Do not place the paper over the agar until it has stopped dripping
Dripping the product onto the agar will skew the results!
Using forceps, Place the product soaked paper onto the designated circle on the agar
Repeat for all products being tested

27. Quality control - procedures
Allow 5 minutes for everything to soak into the agar
Turn agar plate upside down, then place it into the incubator
The lid should be on the bottom at this point
recorder
Record the temperature on the incubator
Everyone
Clean and sanitize work station

28. Bell Work – Day 3
Write your group’s hypothesis as an if/then statement:
Example: If hand sanitizer most effectively kills E. coli, then the zone of inhibition around hand sanitizer will be larger than any other product’s.
Then, attempt to write it without using an if/then statement:
Put today’s bellwork directly into your class journal – not on an index card.

29. objectives
Compare the effects of different products that claim to kill bacteria
Design a controlled experiment
Plan a methodology using appropriate tools to gather precise and accurate data
Determine if data obtained was valid and reliable
Compose and defend a conclusion based on data obtained from a controlled experiment
Publish results of a controlled experiment
Learn sterile handling techniques for bacteria growth
Successful cultivation of bacteria

30. Lab Tech
Obtain your group’s plate from the incubator
Do not open it!

31. results
Decide with your lab group if you will measure the radius or the diameter
Measure the zones for each product
You must measure in mm
Inches = 2.54 cm
2.54 cm = 25.4 mm
Share results with teacher to add to class data

32. Graphing the results Conclusions
Working with your table group, put the class data into graph format.
Conclusions
Using the class data, analyze whether the results obtained support or reject the hypothesis for your group.

33. Bell Work – Day 4
What is bias in an experiment?

34. objectives
Compare the effects of different products that claim to kill bacteria
Design a controlled experiment
Plan a methodology using appropriate tools to gather precise and accurate data
Determine if data obtained was valid and reliable
Compose and defend a conclusion based on data obtained from a controlled experiment
Publish results of a controlled experiment
Learn sterile handling techniques for bacteria growth
Successful cultivation of bacteria

35. Publishing the results
Each group will create a poster that contains the following information:
Research purpose or research question
Hypothesis
1 or 2 sentence methodology summary
Graph of results
Conclusion statement - Should include an overall statement of most effective product and how that relates back to hypothesis
Acknowledge any potential errors &/or necessary improvements

36. Exit ticket
Did this experiment have any confounding variables? If so, what were they?