Micro-organisms and their applications

• How does bacteria replicate?

  By binary fission (cell division)
• What kind of reproduction is binary fission?

  Asexual
• What does the level of bacterial growth depend on?

  Nutrients available and other factors e.g temperature
• What are some methods used to grow bacteria?

  • Nutrient broth solution
  • Agar plate
• How is an agar plate made?

  Created by pouring molten agar into a sterilised petri dishes
• What is spread onto an agar plate?

  Bacteria to form individual colonies
• What is an aseptic technique?

  Techniques to prevent contamination when growing bacteria
• What are some examples of aseptic techniques?

  • Innoculating loop
  • Open the lid slightly
  • Clean bench with 75% ethanol
  • Work by blue flame
  • Sterilise all equipment
• How is an inoculating loop cleaned?

  Sterilised by heating before and after use
• What does opening the lid slightly do?

  Prevents micro-organisms from the air contaminating the dish
• What does cleaning the bench with ethanol do?

  Kills bacteria and fungi
• What does working by a blue flame do?

  Creates convection currents which removes airborne microbes
• Why is all equipment sterilised?

  Prevent contamination.
• Why are petri dishes only incubated at 25 degrees for no longer than 48 hours in school labs?

  To prevent the growth of human pathogens that thrive at 37 degrees (body temperature)
• What does 1 bacteria equal?

  1 colony
• What cannot be seen without a microscope?

  Individual micro-organisms
• What can we estimate about individual bacteria?

  If we count the number of colonies we can estimate the number of original bacteria
• What do bacterial reproduce in?

  Regular intervals
• What does bacteria reproducing at regular intervals allow us to predict?

  How many bacteria will be present at a given time
• What does the fridge do to bacterial growth?

  Slows it down
• What does the freezer do to bacterial growth?

  Stops it
• What does cooking at very high temperatures do?

  Kill bacteria
• What are industrial fermenters?

  Containers used to grow bacteria and fungi in large amounts
• What’s an example of whats grown in an industrial fermenter?

  Penicillium mould
• What does penicillium mould make?

  Penicillin
• What is penicillin?

  An antibiotic
• What are the features of an industrial fermenter?

  Steam inlet, nutrient inlet, water jacket, air inlet and filter, stirring paddles and pH control
• What is the function of a steam inlet?

  Hot steam sterilises the inside
• What is the function of a nutrient inlet?

  Allows sterile nutrients to enter
• What is the function of a water jacket?

  Keeps the temperature inside constant
• What is the function of an air inlet?

  Provides a source of oxygen
• What is the function of the filter on the air inlet?

  Stops micro-organisms from entering
• What is the function of the stirring paddles?

  Keeps the mixture stirred
• What is the function of the pH control?

  The pH is checked to see if it’s at the optimum value
• Why do we use a steam inlet?

  It prevents contamination from unwanted micro-organisms
• Why do we use a nutrient inlet?

  Penicillium needs nutrients to grow and reproduce
• Why do we use a water jacket?

  Penicillium grows best at 23-38 degrees (optimum)
• Why do we use an air inlet?

  Penicillium needs oxygen for respiration
• Why do we use stirring paddles?

  Mixes the micro-organisms and nutrients while keeping the temperature even
• Why do we have a filter on the air inlet?

  It prevents contamination by unwanted micro-organisms