Microbiology

• Equipment


  • agar plate
  • heatproof mat
  • filter paper discs
  • three antiseptics eg. mouthwash, TCP, and antiseptic cream
  • disinfectant bench spray
  • 1% Virkon disinfectant
  • Antibacterial handwash
  • forceps
  • clear tape
  • hand wash
  • wax pencil or permanent marker
  • incubator set to 25°C
• Aseptic techniques

  Used when working with bacteria and fungi
• Aseptic techniques

  • Ensure the microorganisms being investigated do not escape or become contaminated with an unwanted microorganism
  • Prevent the growth of unwanted, pathogenic microorganisms
• Aseptic techniques include

  • No eating or drinking in the lab
  • Wiping bench with disinfectant/alcohol
  • Not growing microorganisms at body temperature
  • Using sterile loops when transferring cultures
  • Flaming culture bottle necks to prevent contamination
  • Sterilising (using an autoclave) or disposing of all used equipment
  • Washing hands thoroughly
• Aseptic technique

  1. Complete the procedure with a Bunsen burner on the bench to kill airborne microorganisms

  2. Pass a metal loop through the flame to sterilise it

  3. Allow the metal loop to cool to prevent any microorganism it touches being killed

  4. Remove the culture bottle lid and sweep the neck of the bottle through the flame to sterilise it

  5. Glide the metal loop through the bacterial culture to inoculate the metal loop with bacteria

  6. Sweep the neck of the bottle through the flame to sterilise it again

  7. Replace the culture bottle lid to prevent contamination

  8. Partially lift the Petri dish lid to prevent the entry of unwanted airborne microorganisms

  9. Gently glide the inoculated metal loop over the surface of the nutrient agar (agar enriched with nutrients and minerals essential for bacterial growth) - this is known as plating

  10. Pass the metal loop through the flame again to sterilise it

  11. Tape the Petri dish lid on

  12. Incubate at 25°C - below body temperature to ensure pathogenic microorganisms do not grow

  13. Incubate upside down to avoid condensation dripping on the bacteria
• Culture

  A colony of microbes, typically on an agar plate
• Inoculate

  To introduce bacterial cells
• Petri dish

  A clear glass or plastic dish, used to grow living cells from organisms so they can be studied
• Nutrient agar

  Agar enriched with nutrients and minerals essential for bacterial growth
• Aseptic techniques are used when working with bacteria and fungi