lab 9

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lab 9
2014-04-27 19:54:26

biol 251 lab 9
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  1. Drinkable water
  2. What are the sources of fecal contamination?
    water source stars at mountain picks to revers that mixed with washes. All of these sources are exposed to human/animal fecal contamination and other pollutants.
  3. coliforms
    • All enterobacterceae
    • All ferment lactose
    • All gram negative rods
    • All anaerobe facultatives
    • All produce gas
  4. What does coliforms and non-coliforms of fecal contamination have in common?
    • They all cause GI tract infections
    • diarrhea, dysentery, and vomiting.
  5. Why the media we used in lab 8 is selective media
    Because it inhibit the growth of gram positive bacteria and select the growth of gram negative
  6. Why is the media we used in lab 8 is deferential media
    It differentiate between lactose fermenting coliforms from other gram negative that do not ferment lactose.
  7. Water screening test
    • A quick test of coliforms in 100 mL of water.
    • The water will change color blue/green and participials will glow under 360 nm UV light if coliforms are present
  8. Why is Eosin methylene blue (EMB) is a deferential media?
  9. Lactose frequenters produce acid:
    • E. coli produce a lot of acid turn media color green shean
    • Other lactose fermenters produce less acid turn the media pink to red/purple
  10. Why is Eosin methylene blue (EMB) is a selective media?
    • Because it selects gram negative growth only
    • Some dyes in this media inhibit gram +
  11. EHA Media (Hektoen Enteric agar)
    • Selective: Contains bile salt that inhibits G+
    • Deferential:
    • E. coli turn agar color to pink, yellow or orange
    • Shigella: blue green
    • Salmonella produce H2S black
  12. MCA (MacConkey agar)
    • Selective: Bile salt & crystal violet inhibit G+
    • Differential:
    • Lactose frementer turn media pink.
  13. Define and list characteristics of coliforms.  Why is water tested for coliforms?
    • Members of enterobactriaceae, facultative anaerobes, produce gas, ferment lactose.
    • Because they can cause GI tract infections
  14. Name three diseases spread through water.
    Dysentery, diarrhea, and vomiting, cholera
  15. Staphylococcus aureus
    • Grow form:  cluster
    • Colony color: Golden yellow
    • Catalase test: positive
    • Infection: MRSA (Methicillin resistance staphylococcus aureus)

  16. Enterococcus
    • Growth form: Chains
    • Colony color: white
    • Catalase test: negative
    • Infection: VRE (vancomycin resistance enterococcus)
  17. Catalase
    Enzyme produced by Staphylococcus that break down oxygen radicals
  18. Staphylococcus in general
    • halotolorant
    • normal residents of the body
    • opportunists can become pathogenic under certain conditions
  19. Mannitol salt plate
    Mannitol is used as sugar

    • Differential media : Because it will turn yellow if mannitol is fermented (S. saprophyticus & S. aureus)
    • Selective media: because it selects for only halotolorant bacteria
  20. What are S aureus, S. saprophyticus and S. epidermis have in common?
    What differentiate between them?
    • All are halotolorant
    • S. epidermis; cause (endocarditis inflammation of the heart lining), Cannot ferment mannitol
    • S. saprophyticus cause UT infection,
    • S, aureus: cause MRSA,
  21. (BAP) Blood agar plate
    • S.epidermis: gamma hemolysis (non hemolysis)
    • S. saprophyticus : gamma hemolysis
    • S. aureus: Beta hemolysis (complete hemolysis)