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20 Cards in this Set
- Front
- Back
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Chemical germicides: Antiseptic.
What was measured? What is "zone of inhibition"? What is MIC (minimal inhibitory concentration)? |
Zone of inhibition was measured; it is a zone of no growth.
Wanted a "lawn of bacteria" MIC is the zone of no growth around zone of no growth. |
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Kirby-Bauer method also known as Anti Microbial Susceptibility Test.
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Mueller-Hinton Agar used. Antibiotic disc sensitivity has specific pore 4mm in depth (reg. agar is 2mm).
Looking for zone of inhibition after incubation. Measure diameter of no growth in mm. Use chart for comparison. |
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Kirby-Bauer: What might be the consequence of pouring the plates 2mm deep instead of 4mm deep?
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Thick agar slows lateral diffusion and thus produces smaller zones than plates held to the 4mm standard.
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Kirby-Bauer: The Mueller-Hinton II plates are supposed to be used within a specific time after their preparation and shold be free of visible moisture. Why?
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Because too much moisture can spread bacteria into the zone of inhibition. You have to use it within a specific time because the time is relative to how the plates support bacteria growth.
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Yeast Wet Mount
What is yeast? |
Yeast is unicellular fungi.
Asexual reproduction (budding) |
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What are molds?
Hypha? Mycelium? Aerial hyphae? Fruiting body? |
Molds are multicellular fungi.
Hypha are multicellular strands of fungi (or filaments). Mycelium - group of hyphae Aerial hyphae - these extend outward from the mycelium into the open air Fruiting body - usually spore bearing, structure that bears spores; haploid. |
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What do the following look like under a microscope? (identify on test by genus)
Saccharomyces cerevisiae (budding yeast) Rhizopus Aspergillus* Penicillium* |
S. cerevisae -
Rhizopus - species that are fast-growing molds that produce white or grayish cottony growth Aspergillus - green to yellow or bown granular colonies with a white edge (conidial) Penicillium - green, powdery, radially furrowed colonies with a white apron and light colored reverse surface (conidial) Different colors of fruiting bodies is a way to help identify. |
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Phenol Red Broth
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Just pH indicator. Add sugar (glucose, lactose, sucrose, etc) to see if we can ferment that sugar to produce acid.
pH~ 7 - media is red basic - yellow (fermentation occured) >7.4 - pink/magenta - deanimation to NH3 This test is best by specifically choosing 1 carbohydrate for fermentation for clearer results. |
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PR
What is peptonization? |
A raise in pH (ie when turns pink).
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MRVP (Methyl Red & Voges-Proskauer)
Methyl Red - mixed acid fermentation - overcomes phosphate buffer in the medium and lowers pH) Incubate -> add methyl red (indicator) -> if turns red, it is positive, glucose was metabolized/fermented. |
Voges-Proskauer
Glucose fermentaion Reagent: alpha-naphthol, then incubate Indicators: VP reagents Testing for special fermentation; if turns red, means we have Acetoin (2,3 butanediol) Red - positive Copper - no charge, negative Same medium as MR |
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What is acetoin?
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An intermediate to make 2,3 butanediol.
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Catalase
Looking for presense of catalase, an enzyme that converts H2O2 to water & oxygen. After incubation, pour H2O2. If bubbles, it is positive for presence of catalase. |
Oxidase
Looking for cytochrome c. oxidase Nutrient agar Oxidase - detects ETC by adding a chromogenic reducing agent color (means can make over 2 ATP) Reagent: chromogenic reducing agent Add reagent, then incubate. If organism turns blue, it is positive for oxidase |
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Nitrate Reduction
Nitrate broth with durham tubes Enzyme - nitrate reductase Can organism use something other than oxygen in ETC? Test for anaerobic respiration. Bubble in tube - positive N2 gas, two step reduction Reagents: A & B reagents Media turns red - positive for nitrate to nitrite, If media does not change, add zinc (catalyst) - media turns red - negative; media does not change - positive. |
Citrate
Simmons Citrate Agar Enzyme - citrate permease Blue - positive for citrate permease Not blue - negative |
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Decarboxylation
Takes amino acid & cuts off carboxyl group Put layer of oil to enhance aerobic conditions, then incubate Purple- positive (>6.8pH) Yellow - neg. (<5.2) |
Starch Hydrolysis
Starch Agar plate Indicator: iodine Enzyme: amylase Looking for type of amylase Add iodine; iodine turns starch black. Media turns black - negative Media clears - positive Enzyme amylase is present when positive |
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Urease
Slant tubes, urease tubes Enzyme: ureanase pink - positive for urease |
Casein Hydrolysis
Skim Milk agar plate Enzyme: caseinase Caseinase digests, so if media clears, it's positive. |
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Gelatin Hydrolysis
Gelatin tube, no agar Nutrient Gelatin in tube Enzyme gelatenase Liquid agar even when cold. Has gelatin in media. Liquid - positive Solidifies - negative |
SIM (Sulfur Indole Motility)
SIM medium; cysteine in medium (and iron) Production of sulfur - systeine disulferase Media turns black - positive for sulfur Add reagents; red layer on top - positive for indole Tryptophan turned to indole Motility spreads beyond tube (means presence of flagella) Cysteine desulferase catalyzes putrefaction of amino acid cysteine to pyruvate Thiosulfate reductase cataluzes reduction of sulfur at end of anaerobic ETC |
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TSI (Triple Sugar Iron)
TSI agar Kliger Iron agar Phenol Red is pH indicator 3 sugars to test for fermentation (glucose, sucrose, lactose)*. Has iron in media so it can turn black, which means positive for cysteine reductase |
Litmus Milk Medium
pH indicator azolitmin how organism metabolizes milk Milk reduction, for lactose fermentation |
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Membrane Filter Technique
Endo Agar (medium) - Selective differential for gram negative organisms (anything that grows on the media is gram-) - Differential media for coliforms (lactose fermentor), usually gram negative rod bacillus Green metalic sheen = lactose fermentation Testing for coliforms |
Fermentation - anaerobic process
Used powdered milk, fermenter is yogurt Used fermenters in yogurt to make yogurt Made lactic acid; wrapped yogurt for anaerobic conditions Used grape juice & saccharomyces as fermenter. Sacch. converted into wine. Produced ethanol, CO2 |
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Bacteriophage Lab
CR63 (Lysis) creating areas of no growth Epindorf tubes Cell lysis, plaques If anything grows, transduction occurs. AMP resistance. |
..cont.
Transfer of a gene for ampicillin Transduction (BE) Plate using AMP (ampicillin in regular agar); anything growing in this is BE resistant Resistance if bacteria grows |
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Protists:
Unicellular, multicellular, eukaryotes Trichomonas Plasmodium Entamoeba Spirogyra |
Helminths:
animal kingdom Taenia (tapeworm) Necator (hookworm) Enterobius (pinworm) Schistosoma |
