BACTERIA PLATES. Ring Around the Rosy Rhyme. Dates back to the Great Plague of London in 1665 (Bubonic Plague). Ring around the rosy, Pockets full of posies Ashes, ashes, We all fall down. Symptoms of the plague included a rosy red rash in the shape of a ring on the skin
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Dates back to the Great Plague of London in 1665 (Bubonic Plague)
Ring around the rosy,
Pockets full of posies
We all fall down.
Symptoms of the plague included a rosy red rash in the shape of a ring on the skin
Pockets and pouches were filled with sweet smelling hers which were carried due to the belief that the disease was transmitted by bad smells
Refers to the cremation of the dead
Refers to all the people dying from the plague.
In the two laboratory lessons that follow, you will start to understand that bacteria are everywhere and that various surfaces have different levels of organisms. It is very important to keep in mind that bacteria can spread from hands to food, from food to food, and from surfaces to food. This cross-contamination can be controlled by the simple measure of thoroughly washing hands and surfaces.
If you are going to test hands and under fingernails for bacteria, wash your hands after you have swabbed these areas.
If your going to test your mouth, do not put Q-tip in mouth!!! Use inoculating loop!
Aseptic technique is a fundamental skill needed for any level of microbiological work. There are THREE basic components:
1) Sterilization: Lab equipment must be heated (>1000C) to kill resistant micro-organisms and their spores. This will prevent contamination of your cultures.
2) Working close to a flame: Never leave an open flame unattended, and always tie back your hair when working with a flame. The flame from a Bunsen burner is used to sterilize inoculation loops to maintain pure cultures.
3) Disinfection: Clean you bench top before and after use, to kill any cells. Wash your hands thoroughly after the experiment.
- Leave all coats, books and bags that are not directly involved with the
lab at the back or side of the room to avoid contamination
- Students with long hair should tie this back to avoid contaminating the
- Always wash your hands with soap and water before leaving the lab
- Do not put pencils, pens, etc. in your mouth; avoid touching your eyes
after handling the samples
- Do not remove the cultures from the lab
- Treat all cultures like they are potential pathogens.
- At the end of the procedure, wipe down your working surface
Before you begin part 2, obtain petri dish and using permanent marker divide the dish in four quarters, label C, 1, 2, 3
Choose your source of microorganism....
If you choose a nonliving source use the Q-tip to swab your source (that has been soaked in boiling distilled) and smear it gently on the agar's surface (All over C, 1, 2,& 3) C will be your control.
If you choose a living source (mouth) provide an oral rinse sample using the bottled water provided. After sterilising the inoculation loop, dip loop into oral sample and transfer an onto the 4 quadrants of the agar plates.
(Exercise Caution not to puncture the agar)
Dip a paper disc in the disinfectant or antiseptic depending on what you choose using forceps that have been sterilized in a Bunsen burner flame.
Open the petri dish slighly to place the disc inside on the agar. (Place disc in area marked 1). Do this twice more with different disinfectants or antiseptics.
Reminder label these areas
Use masking tape to secure the lids of the Petri plate.
Invert the agar plate and place the plate in an incubator (Lab 213), set at 300C.
1) Draw the growth on the plate after 24 hours.
1a) Measure the growth ring around a disk, as indicated by the following diagram.
Four measurements should be taken from the centre of the disk.
b) #1 (mm) #2 (mm) #3 (mm) #4 (mm) Average(mm) Antiseptic
Shape of Colony
1. What chemical agents did you use to slow/stop the growth of microorganisms?
2. Which chemical agent was the most successful?
3. What type of microorganisms grew in the petri dish? (Describe shape, colour, type of edges)
4. Write definitions for antiseptic, and disinfectant.
5. When discussing bacteria the word antibiotics often comes up why is this so?
6. Besides chemicals, what other techniques can be used to stop the growth of microorganisms. (Provide 2)
7. List 3 ways in which industry makes use of microorganisms.
8. List the 3 conditions that typically enhance bacterial growth.