Does hot pepper sauce kill bacteria found on raw oysters?

	Project title: Does hot pepper sauce kill bacteria found on raw oysters?
Difficulty level:	High school
Main link:	None

Hypothesis:

Microbes are found on just about everything we eat. Meat, poultry, and seafoods harbor large numbers of bacteria and other microbes. These microbes might be on the animals when they are caught or slaughtered, or they might get on the food during processing, packaging, or shipping. Heat is one of the best methods of killing microbes, including disease-causing bacteria. Many people, however, eat foods such as oysters raw. Oysters are bottome feeders. meaning they eat decaying matter off of the ocean's floor. Therefore, they contain many microbes when they are harvested. Pathogenic organisms that might be found on these oysters have the potential to make someone sick.

Materials:

Petri dishes (at least eight)
Beakers
Blender
Autoclave
Bunsen burner
Tweezers
Nutrient agar
Seawater
Sterile filter paper disks
Tabasco sauce
About a dozen raw, fresh oysters in their shells
Eyedropper
Adhesive tape
Fine ruler (or vernier calipers)

The Procedure:

Sterilize all the glassware including beakers, Petri dishes, eye droppers, and the blender jar in an autoclave (or use the sterilization technique described in chapter 1). The nutrient agar and seawater must also be sterilized prior to starting the project.
To prepare the Petri dishes, start with liquid nutrient agar. You can create your own from a mix or melt down solidified agar in a beaker. Once the agar is in liquid form, add 1% seawater to the agar. For example, if you are working with 500 ml of liquid agar, add 5 ml of seawater and mix thoroughly.
While the agar is still hot and in liquid form, pour it into each of the eight sterilized Petri dishes. Fill each dish only about 1/3 full. Wait for the agar to solidify.
Once the agar is solid, use sterile forceps or tweezers to place a filter paper disc on the agar in the middle of the first Petri dish, as shown in Fig. 4-1. Pass the tweezers through a Bunsen burner flame a few times before picking up the next blotter paper disc and placing it on the next Petri dish. Continue for all the dishes, passing the tweezers through the flame each time to keep them sterile. The Tabasco sauce will be applied to these discs.
Use a sterile eye dropper to place one drop of Tabasco sauce on the disc in the middle of a Petri dish. Create another identical dish. Label both dishes 1 drop. Put two drops of the sauce on another disc in a Petri dish. Create another identical disc and label them appropriately. Place three drops on discs for two other dishes and label them as well. Leave the last two Petri dishes alone without any sauce to act as the controls; label them as such. Let the sauce dry for at least three hours before continuing.
You are now ready to add raw oysters to each Petri dish. Purchase fresh, raw oysters and shuck them (or have your sponsor shuck them) as you normally would. Prepare another batch of liquid agar as you did earlier by mixing a small amount of seawater with the agar.

Results:

You’ll need 125 ml of agar mixed with 1.5 ml of seawater. While the agar is being readied, prepare the oysters.
Place about one dozen oysters (including both the juice and the meat) in the blender and add 100 ml of seawater so the juice it produces isn’t too thick. Blend thoroughly. Using a sterile graduated pipette, transfer about 10 ml of the oyster juice into the liquid agar that you just prepared and mix thoroughly.
Wait for the oyster/agar blend to cool down slightly, but don’t let it solidify. Pour a thin layer of the agar/oyster juice blend onto the existing agar layer (and filter paper) in each of the eight Petri dishes. Allow this layer of agar to solidify. Be sure all the Petri dishes are labeled with the proper number of drops of Tabasco sauce placed on the filtered paper.
Leave all the Petri dishes at room temperature for 48 hours. The bacteria present in the oyster will grow throughout the nutrient agar. The bacteria are destroyed by the sauce, there will be a halo around the paper discs containing the sauce. Use a fine ruler or vernier calipepers to measure the zone of inhibition around such disc in each plate. Observe all the Petri dishes under a stereoscope if available. Record your data.