How to Grow E-Coli in a Petri Dish

Escherichia coli is a common bacterium named after its founder Theodor Escherich, the German bacteriologist who discovered the organism in 1885. E. coli is gram negative, meaning that when stained it does not show a color. E. coli is found in warm-blooded animals, especially humans, and aids in digestion. Some strains of E. coli are harmful and can cause a host of medical issues. E. coli is widely used as a model bacterium for biological and microbiological experiments because it is easy and relatively inexpensive to obtain and grow.

Things You'll Need

• Bunsen burner
• Bacteria loop
• E. coli culture
• Nutrient agar plate
• Incubator

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Instructions

• 1

  Obtain a culture of E.coli in a nutrient broth. Prepare a nutrient agar filled petri dish. Take a bacteria loop and scoop a loopful of E. coli culture.

• 2

  Put the bacteria on the agar plate. Be sure to keep the lid hovering over the agar surface because of the possibility of contamination from the air around. The air contains impurities that could derail the experiment.

• 3

  For more than one streak, run the bacteria loop through the Bunsen burner flame and cool, then streak the petri dish a second time at a different place on the plate.

• 4

  Once you are done inoculating the dish, incubate the plates for 48 to 72 at 25 degrees Celsius in an inverted position. This avoids condensation from forming. You should have a good growth plate at the end of this process.