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This is a lab about FOOD spoiling microbes.
General Directions : Share Google Documents. Read the directions. Each group will do one species.
A. Pre-LAB : There are five microbes to be tested.
As a pre-lab activity, please find some basic information about the following species used in this lab. Be sure to identify their Kingdom. Explain what type of food , dairy ,meat or vegetable , does the organism spoil? What problem does it cause?: ( Use a Google Doc and collaborate ...share your doc.)
1. Bacillus cereus
2. Penicillium chrysogenum
3. Pseudomonas fluorescens
4. Saccharomyces cervisiae
5. Serratia marcescens
B. Procedure:
Different types of agar will be prepared in labelled plates. You will be assigned to prepare plates with a particular agar. Label the plates with the specific type. Make a shared Google Doc, shared with the whole class:
1. Wash your hands. Sterile technique should be followed throughout the lab. Used items will be placed in a special autoclave bag.
2. Collect four applicator sticks, and assigned petri dishes with each type of agar. There are seven dishes.
The agars have different chemicals and concentrations. For example 30% Sucrose.
3. Remove the applicator stick from the package, being careful not to touch the cotton tip to any surface.
4. With the applicator stick, pick up some of the assigned culture from the culture dish. Streak the culture across the center of the agar in a straight line and ending 1 cm from the edge of the plate. Do NOT "Zig -Zag. You may make three lines. Remember, you will need to measure growth. Growth will be shown by the width of the streak.
5. Repeat steps 3 and 4 for each of the six agar plates , using a fresh applicator for each ( if available).
6. Label the dishes with the culture name, your group name, and the date. Measure the width of the streak in each dish in mm and record it.
7. Incubate the dishes for 7 days , at room temp, 25oC
8. Daily Observations:
Make Daily observations, recording the date and time.
Take measurements of any growth in millimeters, measuring the diameter of colonies.
You must take 3 photos total, to be included in your report.
A written description is required for each photo.
Lab Report: Rubric
This will be written as an Inquiry Lab:
Lab 7 A. Complete and submit the Pre-Lab ( This is submitted separately, before the lab is started.)
Lab 7 B: Complete and submit a complete a lab report as follows:
1. List Materials needed. Be specific.
2. Write a step by step procedure in outline form.
3. Present observations and measurements in a data table.
The main task for the lab report :
4. Make a conclusion, referring to specific evidence in your results.
Make a conclusion about each of your specimens, explaining their reactions to the various concentrations of sucrose and NaCl.
a. Research concepts like plasmolysis.
b. Ionic Compounds ( NaCl) effecting protoplasmic ions , and other chemical effects on microbes
c. Osmotic pressure.
d. How are meats, sauerkraut, fish, butter, and cheeses products preserved?
This is for your group's results only... Do make a statement in the conclusion about the evidence from your data.
If data from the groups is shared, is there a trend that matches your results?
Claim, Evidence and Reasoning
Link for Other Parts of the Lab :
7.C : Periodical Summary and Opinion
Write about it: a. Summarize the issue
b. Comment on the issue; include your opinions, questions, and/or ideas
7.D : Web Research on Medical Issues of food poisoning
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