Detection, Growth and Characterisation

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…