Growing bacterial cultures

• Steps for aseptic technique


  • Carry out all working in front of a lit bunsen burner on a yellow flame
  • Hot agar jelly poured into a sterilised pertri dish and left to cool and set
  • An innoculating loop is passed through a hot flame before it is used to transfer bacteria
  • Petri dishes should only be opened as little as possible on the side facing the bunsen burner
  • The lid of the petri dish should be secured with tape at intervals and stored upside down
  • The cultures should not be incubated above 25 degrees
• All work carried out in front of a bunsen burner


  • the flame creates a convection current above the bench
  • prevents contamination from airborne oragnisms
• Hot agar jelly is used


  • the agar is heated to a high temperature to kill any potential microorganisms that could contaminate the experiment
• Innoculating loop passed through a flame


  • any microorganisms on the loop are killed
  • prevents contamination
• Petri dishes only opened as little as possible


  • decreases the risk of contamination
• The lid should be secured with tape and stored upside down


  • prevents drops of condensation dropping onto the surface of the agar
• Cultures should not be incubated at above 25 degrees


  • restict the growth of harmful pathogens
  • they are more likely to grow at higher temperatures