unknown3final1 - Name: Unknown # 3 Date: 3/26/08 Tube # 13...

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Name: Unknown # 3 Date: 3/26/08 Tube # 13 Unknown Should Have Been: Bacillus subtilis Grading: Possible Received 1. Description of the test performed 5 _______ (Purpose, equations, what it is) 2. Description of the positive/negative Results for the test (what should we be 5 _______ 3. How your organisms responded to each 5 _______ Test 4. How you deduced what organism you 5 _______ Have Points Possible 20 Points Received _________ Comments:
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Introduction: The four possible unknowns that could have been obtained for unknown number three were: E. coli , B. subtilis , Staphylococcus aureus , or Proteus vulgaris. The principle I used to differentiate between the various organisms was the production of clear zones on the starch and skim milk plates. This made it quite obvious that my unknown was B. subtilis because that is the only one that is supposed to test positive for those two plates out of the four unknowns. I was successful in finding my unknown to be B. subtilis because the results from my streak plates were very definitive. Results: From left to right: (mine is left side, but both are the same) Starch agar plate with several drops of grams iodine, Tri-butyrin plate, Skim milk agar plate. For the starch agar plate, once several drops of grams iodine were added, clear zones appeared although they were whitish yellow in some places, but clearer and lighter than the iodine. This was indicative of a positive test for starch hydrolysis. The next plate, the Tri-butyrin plate, showed growth, but no clear zones which meant a negative test. The skim milk, which tested for casein hydrolysis, had clear zones appear around the bacterial growth which meant it was positive for caseinase production. From left to right: tryptophan broth, urea slant, phenylalanine agar slant, KIA slant. For the tryptophan broth, once Kovac’s reagent was added, a brown bubble was formed which was a negative result. The urea slant stayed neon yellow which was a negative test result. For the phenylalanine test, after FeCl2 was added, the bubble on top stayed yellow which was a negative test result. For the KIA slant, the medium turned pink with a tiny amount of yellow on the bottom and white growth on the slant which was a
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This note was uploaded on 05/07/2008 for the course MIC 206 taught by Professor Harris during the Spring '08 term at ASU.

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unknown3final1 - Name: Unknown # 3 Date: 3/26/08 Tube # 13...

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