Culturing Microorganisms

• What is the focus of the practical described in the study material?

  Culturing microorganisms
• What can you grow in the lab according to the study material?

  • Your own microorganisms
  • Test the effects of different antibiotics
  • Observe bacterial growth
• What do antibiotics do to bacteria?

  They are effective at killing them
• What is necessary to grow bacteria in the lab?

  A culture medium
• What components does the culture medium contain?

  Carbohydrates, minerals, proteins, vitamins
• How do bacteria appear when grown on agar plates?

  They form visible colonies on the surface
• What is the process to create an agar plate?

  1. Pour agar jelly into shallow plastic dishes
  2. Allow it to set and cool
  3. Inoculate with bacteria
  4. Observe growth of colonies
• What happens when the jelly cools and sets?

  It can be used to transfer microorganisms
• What temperature should cultures be kept below?

  25°C
• Why should cultures be kept below 25°C?

  To prevent harmful pathogens from growing
• What is the effect of higher temperatures on cultures?

  Harmful pathogens are more likely to grow
• How do industrial conditions differ for culturing microorganisms?

  They allow for higher temperatures
• What can be investigated regarding antibiotics?

  Their effect on bacterial growth
• What are the steps to test the action of antibiotics on bacteria?

  1. Place paper discs soaked in antibiotics on agar
  2. Observe zones of inhibition around discs
  3. Measure effectiveness based on size of zones
• What should be done with the paper discs during the antibiotic test?

  Soak them in antibiotics
• What is the purpose of leaving space between discs in the antibiotic test?

  To avoid overlapping zones of inhibition
• What is a characteristic of antibiotic-resistant bacteria?

  They continue to grow despite antibiotics
• What happens to antibiotic-resistant bacteria in the presence of antibiotics?

  They continue to grow unaffected
• What is the implication of antibiotic-resistant bacteria in cultures?

  They can proliferate despite antibiotic presence
• What are the general steps for culturing microorganisms in the lab?

  1. Prepare culture medium
  2. Inoculate with microorganisms
  3. Incubate at appropriate temperature
  4. Observe and analyze growth
• What should antibiotics do in agar jelly?

  Diffuse into the agar jelly
• What is an antibiotic-resistant bacteria?

  Bacteria not affected by antibiotics
• What happens to non-resistant strains of bacteria when antibiotics are used?

  They will die off due to the antibiotic
• What is an inhibition zone?

  Area where bacteria have died
• What temperature should the plate be left at for 48 hours?

  25 °C
• How does the effectiveness of an antibiotic relate to the inhibition zone?

  Larger zones indicate more effective antibiotics
• What should be used to culture bacteria?

  Uncontaminated cultures
• What should be done to sterilize the medium before use?

  Heat it to a high temperature
• What is the purpose of passing the inoculating loop through a flame?

  To kill unwanted microorganisms
• How should the lid of the Petri dish be treated after transferring bacteria?

  Lightly taped to prevent contamination
• Why should the Petri dish be stored upside down?

  To prevent condensation from falling in
• What should be done to prevent drops of condensation on the agar surface?

  Store the dish upside down
• What is the correct way to store the Petri dish?

  Upside down to avoid contamination
• What should be done to avoid contamination by unwanted microorganisms?

  Use sterile techniques throughout
• What is the consequence of using contaminated cultures?

  It can affect experimental results
• What should be done to prevent unwanted microorganisms from entering the culture?

  Use sterile techniques and materials
• What are the steps to avoid contamination in bacterial cultures?

  • Use sterile techniques
  • Sterilize media before use
  • Pass inoculating loop through flame
  • Store Petri dish upside down
• What factors affect the growth of bacteria in cultures?

  • Antibiotic presence and effectiveness
  • Temperature and incubation time
  • Sterility of culture medium
  • Presence of unwanted microorganisms
• How should you handle antibiotic testing in bacterial cultures?

  1. Soak discs in antibiotics
  2. Place on agar jelly
  3. Incubate at 25 °C for 48 hours
  4. Measure inhibition zones
• What is the significance of the inhibition zone in antibiotic testing?

  • Indicates effectiveness of antibiotic
  • Larger zones mean better inhibition
  • Helps determine resistance of bacteria