Test 3 Micro Lab

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Test 3 Micro Lab
2015-11-12 09:35:39
lab micro
micro lab 302L
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  1. ice nucleation in plants
    cause leaf wilt, outerlayers destroyed by ice crystallization
  2. ice nucleation in killing beetles
    take bacteria, modify it, put in beetles that killed beetles
  3. ice nucleation in snowmaking
    shoot water w/ bacteria, freezes water in 5-7 degrees above normal (saves a lot of energy)
  4. refrigeration vs. incubation
    put out optimum growth temperature
  5. heterotrophic plate count and coliforms
    on serial dilutions,
  6. indicator organisms
    mimics bacteria  but safe
  7. sample size and dilutions
    10 ^-8 past that is diluting to extinction
  8. mineralization
    release of inorganics from the soil
  9. nitrification
    • use ammonia ion as electron and energy source
    • oxididzed to nitrite then to nitrate
  10. denitrification
    • nitrate = final electron acceptor
    • nitrate reduction  leads to nitrogen gas, nitrite, and ammonium ion
  11. ammonification
    extremely important for plants
  12. nitrogen fixation
    • turns atmospheric N into nitrate
    • very costly , costs a lot of ATP, sometimes no choice must make it themselves
  13. root nodules
    • structure formed by some plants for bacteria
    • formed in reaction to fixate nitrogen
  14. rhizosphere
    area in soil that is in direct contact of roots in plants
  15. soil microbes
    bacteria in worm allows the worm to decompose food
  16. most probable number technique
    • estimate number of coliforms present in 100 mL of a sample using a statistical approach. 
    • confirmed: use BGLB, confirms coliform growth, green color: > 90%
    • presumptively: doesn't screen out all non-coliforms, , presumptively determines presence or absence of coliforms
  17. blood agar plate and optochin/bacitracin test
    • 1. use blood plates, use both antibiotics (stated above)
    • 2. esculetin:makes black color
  18. CAMP test
    • 1. perpendicular line test, s. aureus in middle and strep. agalactaie on one end with s. pyogenes on other side
    • 2. group b strep acts together w/ beta -hemolysin produced by the s.aureus, enhancing hemolytic effects, making arrowhead
  19. lytic activity of tears
    lysozome: cell fractionation, good at breaking down gram + bacteria
  20. snyder test
    tests for pH of saliva which indicates susceptibility to dental careis
  21. coliforms
    • group of organisms w/  6 characteristics
    • 1. gram -
    • 2. rods (bacillus)
    • 3. facultative anaerobes
    • 4. utilize lactose
    • 6. ferments gas
  22. indicator organisms
    presence indicates probability of pathogens
  23. kochs postulates
    • 1. The microbe must be absent in healthy host               
    • 2. You must be able to isolate the pathogen and grow it outside of the host               
    • 3. If you reintroduce the isolate into a healthy host you get the original disease               
    • 4. You must be able to re-extract original disease from the host.
  24. blood agar plate
    TSA plate with sheep’s blood
  25. hemolysis
    break down of hemoglobin
  26. alpha hemolysis
    partial or incomplete- looks greenish-yellow from partial break-down of hemoglobin
  27. beta hemolysis
    complete break-down of hemoglobin- the plate with be clear- no red
  28. gamma
    no hemolysis
  29. mannitol salt agar
    • differential and selective               
    • If fermentation occurs the plate will be yellow               
    • 7.5% NaCl inhibits gram negative bacteria growth               
    • E. Coli can’t grow under these conditions
  30. vogel -johnson agar
    • differential and selective- primarily used in isolation of staphylococcus               
    • If mannitol fermentation occurs the plate will be yellow               
    • If tellurite reduction occurs the plate shows dark gray or black dots.               
    • E. Coli doesn’t grow under these conditions.
  31. Blood agar plate and optochin/ bacitracin test
    • Spread streptococcus pyogenes and S agalactiae on each half of one plate and drop both antibiotics on the plate, spread them apart.               
    • Zone of inhibition means the antibiotic works
  32. bile esculin test
    • tests for ability to break down (metabolize) esculin, bile is selective                
    • dark brown/black color is positive
  33. CAMP test
    • distinguishing group b strep from other beta-hemolytic strep               
    • Camp Factor- produced primarily by strep A, inhances hemolysis
  34. lytic activity of tears
    lysozyme is produced by tear ducts and mucous membranes to control gram positive bacteria. Tests for evidence of bacterial inhibition.
  35. snyder test
    tests for pH of saliva                High pH in saliva breaks down calcium making your teeth rough- bracteria may stick to them easier- producing cavities                Yellow (acidic) result means you’re susceptiable to tooth decay.
  36. membrane filtration techniquw
    disposable and expensive
  37. presence/absence technique and Konfirm test
    huge money saver. Same princible as MPN but not quantitative. Just gives a yes or no
  38. nitrate reduction test
    • nitrate broth tubes               
    • Add 5-7 drops of nitrate a and b if it turns pink it means nitrite is present               
    • If not pink after 5 mins add zinc if still doesn’t turn pink then the nitrate has been completely broken down
  39. nitrate free broth
    • selective broth that lacks nitrogen (other than nitrogen in the atmosphere) only nitrogen fixing bacteria grow here               
    • Positive results- presence of bubbles and pellicle (white or slimy layer on surface of broth)
  40. nesslers reagent ammonification test
    • used to identify bacteria able to produce ammonia by deamination of organic compounds.               
    • No color change- no ammonia is present               
    • Pale yellow- small amount of ammonia produced               
    • Deep yellow- moderate amount of ammonia produced               
    • Brown color- large amount of ammonia produced
  41. Heterotrophic plate count and coliforms-
    serial dilutions plate on TSA look for coliforms and spoiling agent.
  42. Grams vs ml vs Cm^2
    Milk- serial dilutions                                Meat- amount of meat/ amount of liquid
  43. sample size in dilutions
    • in most cases you don’t need to go past 10^-8 dilution                               
    • Extinction- no more bacteria present