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Micro - Labs
Stack #79601
Question | Answer |
---|---|
Gram Stain | 30 sec crystal violet; 10 sec Gram's iodine; 30 sec Gram's alcohol; 30 sec Safranin - Stain is different between - and +: crystal violet is picked up by cell and reacts with Iodine to form CV-I which is larger than orginal crystal violet that entered |
Gram Positive | purple; CV-I cannot be washed out |
Gram Negative | pink; decolorizing agent (alcohol) dissolves lipopolysaccharidelayer, and CV-I washes out thru thin layer of peptidoglycan |
Endospore Test | place paper of smear and cover with Malachite Green; steam for 5 min; wash with water; cover smear with safranin for 30 sec; wash with water |
Gelatin Test | test for gelatin hydrolysis; reagent = Nutrient Gelatin; solid, positive growth = positive |
Urease Test | reagent is Urea agar; pink = positive |
Phenylalanine Deamination | slant of phenylalanine; observe growth; add 4-5 drops of ferric chloride on growth; dark green color = positive |
MIO [motility, indole, ornithine] | stab MIO tube; observe for growth; observe color [purple = positive, yellow = negative]; add 4-5 drops of Kovacs reagent - red color = positive |
TSI plate | hydrogen sulfide production - stab peptone iron tube; observe for growth; black in butt of tube = positive for production |
Nitrate Reduction | tubes of Nitrate broth; observe for gas production; add 4 drops Nitrate A and 5 drops Nitrate B: red color in 30 sec = positive; negative - add small pinch of zinc: red color after 20-30 sec = positive |
EMB Plate | Eosine Methylene Blue (reagent); observe growth; color is due to acid production; Gram neg = metallic green color |
OF Glucose | distinguish Fermentative from Oxidative metabolism: inoculate 2 tubes; pour mineral oil over one tube; observe presence of growth = motility; yellow color = acid metabolized = Fermenter |
Starch Hydrolysis | determine in org release Amylase: Starch agar; flood with Gram's iodine; observe halo effect; clear area = positive, dark blue = negative |
MRVP (methyl red and Voges-Proskauer) | 2 test tubes: 1 - 5 drops methyl red; red color = positive = acid produced from glucose; 2 - 12 drops VPA and 2-3 drops VPB; red = positive |
Fermentation | Glucose, Lactose, and Sucrose - observe color (red or yellow) ans gas production: yellow & gas = acid produced as a result of fermentation |
Oxidase Test (TSA Plate) | streak plate; add oxidase reagent; observe for color change; no change = negative; pink to blue to black = positive |
Catalse Test | test for aerobic respiration - streak plate; add hydrogen peroxide; observe for bubble formation; bubbles = positive |