Making bacteria in a lab
- You’ll need a clean, microwave-safe container (a quart-sized bowl works great) to mix and heat the agar with water. These mixing proportions make enough nutrient agar to prepare two halves of the Petri dish. Mix 1/2 teaspoon agar (about 1.2 grams) with 1/4 cup (60 mL) of hot water and stir. Bring this mixture to a boil for one minute to completely dissolve the agar. CAUTION: Adult supervision is required to boil water. If you are using the microwave oven to boil the mixture, be careful not to let the solution boil over. The mixture should be clear with no particles floating around in the solution. Allow the mixture to cool for 3 to 5 minutes before moving on to the next step.
- Separate the Petri dish (there’s a top and a bottom) and carefully fill the bottom half of the Petri dish with warm agar nutrient solution. Use the top half of the Petri dish to loosely cover the bottom portion (set the lid ajar to allow moisture to escape) and allow the solution to cool and harden for at least an hour.
- It’s time to collect some bacteria on the end of a cotton swab. The classic test is to roll a clean cotton swab in your mouth and then to lightly draw a squiggle with it on the gelled agar. However, many people like to test something even more gross like the keys on your computer or the television remote control. Unless someone recently cleaned the buttons on the TV remote, you’re in for some real YUCK in a few days.
- Consider all of your options below (or come…