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Youll use your loop to streak an eosin methylene blue

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You’ll use your Loop to streak an Eosin Methylene Blue (EMB) Plate from an Isolated Colony on a Patient Sample Plate. These Plates are designed to detect Bacteria that can ferment Lactose. The resultant Acid Production precipitates Dyes in the Medium. E. coli Colonies will be dark Purple surrounded by a Fly-Butt Metallic Green Sheen. Enterobacter aerogenes Colonies will be Hot Pink. 1. Direct Isolation You will obtain a “Patient” Sample of a Direct Isolate from the Human Rectum. This Sample will contain E. coli or Enterobacter aerogenes . You’ll use a Loop to streak from an isolated Colony onto an Eosin Methylene Blue (EMB) Plate and a Nutrient Agar Plate. The Plates will then be incubated at 37°C for 24 Hours.
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Lab 1 Page 32 2. Selection E. coli Colonies on EMB will be Purple surrounded by a characteristic Fly-Butt Metallic Green Sheen. Enterobacter aerogenes Colonies on EMB will be Hot Pink. 3. Purification A Gram Stain of Bacteria from an Isolated Colony on your Nutrient Agar Plate should reveal Gram Negative Rods. However, when E. coli are rapidly dividing they may take-on a shortened, Rugby Ball Appearance that makes them almost look like Cocci. 4. Identification Isolated Colonies on a Nutrient Agar Plate will be used for Biochemical Identification Tests. Both E. coli and Enterobacter aerogenes are Oxidase Negative. The IMViC Test is used to distinguish E. coli from Enterobacter . The IMViC Test consists of the combined Results of four Biochemical Tests: Indole, Methyl Red, Voges-Proskauer and Citrate (the ”i” was inserted to supply a Vowel). E. coli and Enterobacter aerogenes give neatly Reciprocal Results for each of these Biochemical Tests: • E. coli is Positive for the First two Tests and Negative for the last two Tests, • Enterobacter aerogenes is Negative for the first two Tests and Positive for the last two Tests. Biohazard Note Your “Patient” Enteric Isolate will be either E. coli or Enterobacter , but not both. Enterics are Minor Constituents of the Flora of the Human Gut. Enterobacter is Non-Pathogenic. E. coli is a Pathogen. It can cause GI Tract Infections that will induce a Diarrhea that is Loud and Horrible. _______________________________________________________________________ “I've been waiting for you, Obi-Wan. We meet again, at last. The circle is now complete. When I left you, I was but the learner; now I am the master.” ‘Only a master of evil, Darth.’ “Your powers are weak, old man.” You can't win, Darth. If you strike me down, I shall become more powerful than you could possibly imagine.’ © 1977 Lucasfilm, Ltd.
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Lab 1 Page 33 Streaking When a single Bacterium is placed on the Agar Surface of a Petri Plate, it will begin growing. (When we use the Term “grow” in Microbiology, we’re talking about Numbers of Bacteria, not the Size of the Bacteria.) After from 12 and 24 Hours (a loosely defined Time Period for which we’ll use the loosely defined Term “Overnight”) this single Bacterium will have given rise to a large Number of Bacteria -- so large a Number of Bacteria, in fact, that you’ll be able to see a small Button on the Petri Plate. Each of these Dots is called a Colony and each
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