Exam 4 Notes

Exam 4 Notes - Exam 4 Microbiology Lab BACTERIOSTATIC...

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Exam 4 Microbiology Lab BACTERIOSTATIC ACTION AND ACID-FAST STAINING: -Bacteria can survive a large amount of environmental hazards, from pH differences, to salt concentrations, to nutrient deprivations. -But certain things have evolved that can greatly effect bacteria: Bacteriostatic and bacteriocidal agents BACTERIOSTATIC AGENTS: -Inhibit microbial growth, but do not kill the microbe -Usually requires the immune system to dot that BACTERIOCIDAL AGENTS: -Kills the bacteria, provided the concentration is high enough -Remember back to the Streptomycin plates of Exp 20 HOW TO TELL THE DIFFERENCE: -Growth on a plate with a reagent -If no growth occurs, restreak the ORIGINAL streak onto a media with no reagent added -Growth Results: BACTERIOSTATIC: -If there is growth (as removal of the bacteria from the agent allowed growth to continue) BACTERIOCIDAL: -No growth (as the bacteria can was killed/rendered nonviable) BACTERIOSTATIC: -Tetracycline -Spectinomycin -Chloramphenicol -Crystal Violet Stain Solution BACTERIOCIDAL: -Vancomycin -Streptomycin -Methicillin -Kanomycin MYCOLIC ACIDS: -All bacteria posses a Peptidoglycan Layer, while other organisms do not -While this layer is fairly uniform b/w bacterial species, some species alter it by the addition of Mycolic Acid -Mycolic Acids are long chains of carbon Fatty acids (60-90 Carbons) which give the bacteria a waxy coating -This makes the bacteria highly resistant to drying out, though also makes nutrient uptake difficult, resulting in slow growth
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-Mycobacterium Tuberculosis (the causative agent of TB) is a bacteria which uses these Mycolic Acids -Because of this waxy layer, these bacteria are safe from a large number of normally devastating effects -BUT this also makes them difficult to visualize b/c conventional stains just won’t adhere to the waxy layer! ACID FAST STAINING: -Similar to the Malachite Green Spore Stain, heat is used to help a lipophilic dye incorporate into the layer -A strong decolorizer is then used to clear any non-Mycolic acid containing bacteria of the stain, and a counterstain is applied EXP 25: -Grab a NA plus Crystal Violet Plate -Divide in quarters -Inoculate a SINGLE STREAK of E. Coli, S. Marcescens, B. Subtilis, and M. luteus is a quarter EXP 36: -Make a smear of the Mycobacterium smegmatis up at the front of the room -Air dry and heat fix the cells -Cover the smears with carbol fuchsin, and steam them (like what was done with the Malachite Green Stain) for 3-5 minutes, not letting the stain dry -Allow the slide to cool and then rinse the slide off -Decolorize with 3% HCL from the dropper bottles -Rinse with water -Stain with Methylene Blue for 30-60 seconds -Blot dry and observe DIRECTIONS: -Using the culture given to you (either B. Subtilis or M. luteus), dilute 1 ml into 9 ml sterile water -Plate 0.1 ml of dilution onto a NA plate -Divide a plate into quarters. At the center of each quarter place a different paper disk that has been soaked in a chemical/agent (Iodine, Rocal, Mouthwash, and Frank’s Red Hot Tabasco Sauce)
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This note was uploaded on 04/23/2009 for the course BIO 201 taught by Professor Paquette during the Spring '09 term at Rhode Island.

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Exam 4 Notes - Exam 4 Microbiology Lab BACTERIOSTATIC...

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