topic seven

• Freezing stops bacterial growth and refrigeration slows down bacterial growth
• bacteria grows rapidly at around room temperature and above, bacteria growth is slower at higher temperatures.
• aseptic


  free from contamination of microorganisms.
• pathogen


  a disease causing microorganisms
• aseptic technique

  • disinfecting work area with disinfectant spray
  • sterilising equipment by autoclaving before the experiment
  • only lifting petri dish 45 degree angle
• One colony has grown from one single bacterium. Colonies are a high number of bacteria that have grown together.
• if there are many colonies on a plate some may overlap this is known as clumping.
• you cannot accurately estimate the number of colony forming units if clumping has occurred
• advantages of using a fermenter

  • predictable product
  • control and monitor conditions
  • efficent
• the fermenter must be kept at certain conditions to ensure maximum growth of Penicillum
• the factors that must keep constant on the fermenter

  • Tempreture
  • pH
  • sterile air
  • sterile nutrients
• plating

  growing a culture of bacteria in a sterile petri dish
• fermenter


  a machine which is used commercially to grow micro-organisms such as penicillin
• agar


  a nutrient jelly used to grow cultures
• inoculating loop


  a sterile loop used to transfer bacteria onto an agar plate