Micro-organisms

• What is the main topic of the notes provided?

  Micro-organisms
• What is the purpose of culturing micro-organisms?

  • Increase population numbers
  • Enable easier study of micro-organisms
  • Form visible colonies from individual cells
• What can be seen with the naked eye after culturing bacteria?

  Bacterial colonies
• How does a bacterial colony arise?

  From a single cell
• What can lead to misleading estimates of bacterial numbers?

  Clumping of cells
• What are the two methods of culturing micro-organisms mentioned?

  • Solid agar
  • Nutrient broth
• What do culture media contain for micro-organisms?

  Essential nutrients
• What is the purpose of aseptic techniques?

  • Reduce contamination from other micro-organisms
  • Ensure accurate experimental results
• What should be done to all equipment before an experiment?

  Sterilise all equipment
• Why is the inoculating loop held in a Bunsen burner flame?

  To kill any bacteria present
• What should be done to the rim of the culture bottle?

  Flame the rim
• What does flaming the rim of the culture bottle create?

  An updraft of air
• How should the lid of an agar plate be lifted?

  Only slightly and low
• What happens to bacteria at high temperatures?

  They are killed
• What is the effect of low temperatures on bacterial growth?

  The rate of growth decreases
• Why is food refrigerated?

  To slow the growth of micro-organisms
• What does freezing food do to micro-organisms?

  Completely stops growth
• What is penicillin?

  An antibiotic
• Which fungus produces penicillin?

  Penicillium
• What conditions must be controlled in a fermenter for penicillin production?

  • Temperature (23 to 28 degrees Celsius)
  • Oxygen levels (aerobic respiration)
  • pH (around 6.5)
  • Nutrient levels (low for penicillin production)
• How is temperature controlled in a fermenter?

  Using a cooling jacket
• Why does Penicillium require oxygen?

  For aerobic respiration
• How is pH monitored in a fermenter?

  Using a pH probe
• What happens to nutrient levels once growth has started in a fermenter?

  No further nutrients are added
• What happens to the liquid medium after approximately 200 hours in a fermenter?

  It is drained and filtered
• What is done to extract penicillin after filtering?

  Chemicals are added