Detection, Growth and Characterisation

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DETECTION, GROWTH AND CHARATERISATION

  • Gram negative bacteria
    • dont retain cystal violet dye - gram staining protocol
  • Gram positive bacteria
    • stained dark blue/violet - gram staining
  • structural differences - bacterial cell walls
  • Binary fission (prokaryotic fission) - asexual reproduction=cells genetically identical
    • chromosome replication begins - one copy origin moves - other end cell
    • replication continues. one copy origin=each end. cell elongates
    • replication finishes. plasma membrane grows inward. new cell wall deposited
    • two daughter cells
  • requirements - bacterial multiplication
    • ideal temperature
      • pyschrophiles (cryophiles) - below 20 C
      • mesophiles - 20-45 C
      • thermophile - over 45 C
    • water activity - aw.
      • intensity - water associates with non aqueous molecules. higher aw=support more microorganisms
    • time, nutrients, oxygen/anaerobic conditions, absence of competition, absence of antibacterial substances, pH
  • reproduction - fungi
    • asexual
      • spore producing structures (n)
      • spores (n)
      • germination
      • mycellum 
    • sexual
      • spore producing structures (n)
      • spores (n)
      • germination
      • mycellum (n)
      • plasmogamy (fusion of cytoplasm)
      • dikaryotic stage(n+n)
      • karyogamy (fusion of nuclei)
      • diploid stage (2n)
      • meiosis
  • structure
    • spore/sporangium
    • sporangiophore
    • hypha
    • rhizoid
  • culturing microbes
    • inoculation=introduction of sample - container media - produce culture observable growth
    • isolation=separating species
    • incubation=conditions - allow growth
    • inspection
    • identification
  • inoculation+isolation
    • individual bacterial cell - grow mound cell=isolated colony=one species
    • bacteria grown (cultured - incubation) - inspected+identified
  • agar - seaweed=complex polysaccharide - red algae
    • preparing solid medium=solid - room temperature
    • no nutritive value - moisture
    • not affected - bacteria growth 
    • melts - 98 C. sets - 42 C
    • 2%=solid medium
  • incubation - humidity, oxygen, carbon dioxide, temperature
    • microbe multiplies - produces macroscopically observable growth
  • bacterial growth curve - culture
    • lag
      • no multiplication
    • log
      • rapid multiplication 
    • stationary 
      • bacteria remain constant. number produced=number dying
    • decline
      • bacteria decrease
  • inspection= observation: macroscopic+micrscopic
    • pure culture=grows single known species microorganism 
    • mixed culture=two/more identified species microorganism
    • contaminated culture=once pure/mixed…

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