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ice nucleation in plants
cause leaf wilt, outerlayers destroyed by ice crystallization
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ice nucleation in killing beetles
take bacteria, modify it, put in beetles that killed beetles
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ice nucleation in snowmaking
shoot water w/ bacteria, freezes water in 5-7 degrees above normal (saves a lot of energy)
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refrigeration vs. incubation
put out optimum growth temperature
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heterotrophic plate count and coliforms
on serial dilutions,
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indicator organisms
mimics bacteria but safe
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sample size and dilutions
10 ^-8 past that is diluting to extinction
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mineralization
release of inorganics from the soil
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nitrification
- use ammonia ion as electron and energy source
- oxididzed to nitrite then to nitrate
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denitrification
- nitrate = final electron acceptor
- nitrate reduction leads to nitrogen gas, nitrite, and ammonium ion
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ammonification
extremely important for plants
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nitrogen fixation
- turns atmospheric N into nitrate
- very costly , costs a lot of ATP, sometimes no choice must make it themselves
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root nodules
- structure formed by some plants for bacteria
- formed in reaction to fixate nitrogen
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rhizosphere
area in soil that is in direct contact of roots in plants
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soil microbes
bacteria in worm allows the worm to decompose food
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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
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blood agar plate and optochin/bacitracin test
- 1. use blood plates, use both antibiotics (stated above)
- 2. esculetin:makes black color
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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
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lytic activity of tears
lysozome: cell fractionation, good at breaking down gram + bacteria
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snyder test
tests for pH of saliva which indicates susceptibility to dental careis
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coliforms
- group of organisms w/ 6 characteristics
- 1. gram -
- 2. rods (bacillus)
- 3. facultative anaerobes
- 4. utilize lactose
- 6. ferments gas
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indicator organisms
presence indicates probability of pathogens
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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.
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blood agar plate
TSA plate with sheep’s blood
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hemolysis
break down of hemoglobin
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alpha hemolysis
partial or incomplete- looks greenish-yellow from partial break-down of hemoglobin
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beta hemolysis
complete break-down of hemoglobin- the plate with be clear- no red
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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
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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.
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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
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bile esculin test
- tests for ability to break down (metabolize) esculin, bile is selective
- dark brown/black color is positive
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CAMP test
- distinguishing group b strep from other beta-hemolytic strep
- Camp Factor- produced primarily by strep A, inhances hemolysis
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lytic activity of tears
lysozyme is produced by tear ducts and mucous membranes to control gram positive bacteria. Tests for evidence of bacterial inhibition.
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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.
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membrane filtration techniquw
disposable and expensive
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presence/absence technique and Konfirm test
huge money saver. Same princible as MPN but not quantitative. Just gives a yes or no
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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
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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)
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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
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Heterotrophic plate count and coliforms-
serial dilutions plate on TSA look for coliforms and spoiling agent.
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Grams vs ml vs Cm^2
Milk- serial dilutions Meat- amount of meat/ amount of liquid
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sample size in dilutions
- in most cases you don’t need to go past 10^-8 dilution
- Extinction- no more bacteria present
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