microbiology

• How do you prepare an uncontaminated bacterial culture using an aseptic technique?

  Mark the bottom of an agar plate with the different antiseptics you are going to use.

  Place the antiseptics onto small paper discs and slightly lift the lid of the agar plate and use forceps to place them onto the agar gel

  Loosely tape the lid to the agar plate and place it in an incubator at 25 degrees for 48 hours

  Measure the diameter of the clear zones without taking off the lid
• What are the safety precautions for this practical?

  Wear safety goggles when handling the disinfectants

  Wash your hands before handling the bacteria
• Why do we sterilise everything and tape the lid to the agar plate?

  There are lots of microorganisms like bacteria and fungi naturally in the air that can contaminate the culture
• Why do we place the agar plates upside down into the incubators?

  To avoid moisture dripping down from the lid when it
• How do we make sure everything remains sterile and doesn't risk contamination?

  Clean the workspace with disinfectant solution

  Sterilise an inoculating loop by passing it through a bunsen burner flame

  Open the sterile agar plate near a bunsen burner to kill bacteria in the air
• What is the inoculating loop for?

  Evenly spreading bacteria onto the plate so that we can see the areas where the zones of inhibition are around the antibiotic discs