Study guide 2

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Author:
krys
ID:
105969
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Study guide 2
Updated:
2011-10-03 03:40:52
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Study guide
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Microbio
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  1. Pure culture
    contain only one type of organism in any type of media
  2. colony
    genetically identical group of organisms, arise from a single cell
  3. criteria for isolated colonies
    distance from other colonies
  4. Not flaming btw Area 3 & 4
    few organisms remain btw area 3 and on loop, if u flame, no bacterial growth will occur on area 4
  5. why can't u cross track
    when u cross track, pick up more microbes and make dilution process more difficult
  6. loop should not go near area 1
    • area 1 is confluent, diluted micrboes from area 3will be concentrated again
    • no isolated colonies will appear in area 4
  7. Cultural characteristics
    • Form
    • texture
    • optical characteristics
    • color (pigmentation)
  8. Starch hydrolysis
    • Enzyme1: Amylase,
    • Product: Maltose
    • Enzyme2: Maltase
    • Product: glycosis (energy)

    • Media: Starch Agar plate
    • (-) amylase & maltase- blue black precipitation around growth
    • (+) amylase & maltase - no starch left, no blue black precipitation
  9. Caesin Hydrolysis
    • Enzyme: protease, caseinase
    • Product: amino acids
    • Media: milk agar plate
    • No zone of clearing around growth: (-) proteolysis, (-) caseinase
    • Zone of clearing around growth: (+) proteolysis, (+) caseinase
  10. Gelatin hydrolysis
    • Enzyme: gelatinase
    • Product: amino acid
    • Media: Nutrient gelatin deep tube
    • ** Need to refrigerate for 30 mins after incubation to read the result

    liquid after 48hrs incubation and 30mins refrigeration: rapid gelatin hydrolysis, (+) gelatinase

    Not liquid after all incubations and refrigerations: (-) gelatinase
  11. Why u shouldn't shake gelatin tube after incubation
    Mixed hydrolyzed and unhydrolyzed gelatin = false negative
  12. why carbs fermentation tube results should be read in 48 hrs
    after 48 hrs peptone may be broken down and alkaline products produced
  13. Results
    • Yellow - (+) fermentation
    • Original red - (-) fermentation
    • deep purple or hot pink - (+) alkaline, (-) fermentation
    • Gas in tube - (+) gas production
  14. why is it important to check bacterial growth if the tube is red?
    • in order to make sure fermentation has occured,
    • if no bacteria, no fermentation
  15. Hydrogen Sulfide test
    Why use peptone iron deep
    • 1. to enhance anaerobic respiration
    • 2. to allow observation of motility
  16. H2S result
    • Black precipitate along the stab = (+); H2S production
    • No black precipitate along the stab = (-) H2S production

    • Growth not restricted to stab line = (+) motility
    • Growth restricted to stab line = (-) motility
  17. Indole production test
    • Enzyme: tryptophanase
    • Media: tryptone broth
    • Reagent: Kovac's reagent
    • (+) : red layer on top of media
    • (-): no red layer formed
  18. Methyl red test
    • To differentiate E.coli and Enterobacter
    • Media: MRVP broth
    • Reagent: methylred reagent
    • (+) : red= (+) for acid end product
    • (-): colorless (yellow) = (-) for acid end product
  19. VP test
    • Media: MRVP broth
    • Reagent: Barritt's Reagent
    • (+) = rose color within 15 mins, (+) for non acidic and neutral end products
    • (-) = no color develops within 15 mins = (-) for nonacidic or neutral end products
  20. Citrate Utilization test
    • Enzyme: citrease permease ; citrease
    • Media: Simmon's citrate agar slant
    • (+) = growth of bacteria, blue coloration = (+) citrease, (+) citrease permease
    • (-) = no growth on slant, remains green = (-) citrease, (-) citrease permease
  21. Urease test
    • to identify Proteus Vulgaris
    • Urease: hydrolyze urea and form alkaline end product
    • Media: Urea Broth (contain phenol ph indicator)
    • (+) : deep pink = (+) urease (alkaline)
    • (-) : no color change = (-) urease

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