Aseptic techniques

• Aseptic techniques 


  When were bacteria and fungi in the laboratory, It is very important that great care is taken to avoid:

  • Contamination of the culture used
  • The growth of unwanted pathogenic microorganisms

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• Using aseptic techniques

  1. Pass metal loop through the flame of Bunsen burner
  2. Allow metal loop to cool
  3. Remove lid of the culture bottle (Tube A) and glide the loop over the surface of the agar without applying any pressure. This is inoculation
  4. Replace the lid of culture bottle to prevent contamination. When doing this , sweep the neck of the bottle through the flame to destroy any airborne microorganisms
  5. Spread the microbes over the surface of the agar in Petri dish (B) by gently gliding the metal loop over the nutrient agar surface - called plating.
• Aseptic continued 


  5. Important to hold the petri dish lid at an angle as this will reduce chance of unwanted microbes from the air entering the dish

  6. The metal loop can then be heated again to a high temperature to ensure that any microorganisms remaining on the loop are destroyed

  7. The Petri dish should be taped and then incubated in an oven at 25°C

  8. When carrying out the transfer it is important to work close to a Bunsen burner as this creates an upward current of air that carries microorganisms in the air away from the area where the microorganisms are being transferred.
• Techniques continue 


  8. Thus avoiding contamination

  9. When the investigation is complete, it’s important to clean all work surfaces and hands and safely dispose of bacterial cultures by following instructions. Autoclaving sterilise glass Petri dishes and culture bottles.
• Autoclaving 


  Heating at high temperatures and pressures