BY4 - Microbiology

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  • BY4 - Microbiology
    • Aseptic Techniques
      • Purpose
        • To prevent contamination of micro-organisms onto the agar plates.
        • To prevent contamination of micro-organisms from the agar plates to the environment.
      • Sterilise equipment by heating it to 121 degrees for 20 minutes.
        • Autoclaving
      • Flame the loop  in the Bunsen burner.
      • Flame the spreader after dipping it in alcohol.
      • Flame the neck of the tube/bottle to create an updraft.
        • Also to minimise contamination.
      • Disinfect bench
      • Lift lid of the petri dish enough to insert the loop or spreader.
      • Wash hands before and after.
    • Conditions necessary for growth
      • Essential nutrients
        • Growth
        • Maintenance
        • Multiplication
        • Supplied in a suitable medium.
            • Glucose = Carbon source
            • Nitrogen in the form of amino acids and proteins.
              • For protein synthesis
            • Vitamins are needed in small amounts ( e.g. B3 or B6)
            • Mineral salts (e.g. K+ or Ca+)
            • Water
      • Environmental Variables
        • Micro-organisms grow best at a specific temperature and pH
          • Optimum conditions
        • Temperature
          • Affects enzymes
          • Ranges from 1 to 5 degrees for ocean bacteria
          • 70 degrees for bacteria in hot springs
          • 37 degrees for bacteria living in mammals
        • Optimum pH is approx. pH7 for bacteria
        • Optimum temperature for bacteria grown on agar plates is 25 degrees


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