1.9 - Culturing Microorganisms

• What are factors affecting the speed of bacterial growth?

  Temperature

  Nutrient availability

  Moisture

  Oxygen
• What are the mediums used to grow bacteria?

  Nutrient broth

  Agar
• What are examples of aseptic techniques?

  Cleaning surfaces with disinfectant

  Washing hands with antiseptic soap

  Sterilising all equipment

  Creating a sterile field with a Bunsen burner

  Growing bacteria in incubators set to a maximum of 25°C (prevents growth of harmful bacteria)
• Steps to growing bacteria:

  1. The inoculating loop is sterilised by being put into the Bunsen burner flame until red hot.
  2. Inoculating loop is then let to cool in the air.
  3. Lid from the bacterial culture bottle is removed.
  4. Neck of the bottle is put into flame - moved air out and prevents any other microorganisms from entering and contaminating the solution.
  5. Inoculating loop is placed into solution
  6. Solution bottle is closed
  7. Zigzag streaks made on the agar jelly using loop
  8. Petri dish is closed and stored upside down in an incubator.
• When bacteria are grown on agar plates, each visible group of bacteria is referred to as a what?

  Colony
• Why is the Petri dish only partially lifted?

  To prevent the entry of microorganisms from the air
• What is the term for the procedures used to prevent contamination when culturing microorganisms?

  Aseptic techniques