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07.Epidemic_Biochemicals

Oxidase positive pseudomonas the addition of oxidase

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• Oxidase Positive (Pseudomonas ) The Addition of Oxidase Reagent will change the Color of a Goober of Bacteria on a Piece of Filter Paper to dark Blue within about 10 Seconds. • Oxidase Negative (Enterobacter and/or E. coli ) The Addition of Oxidase Reagent will not change the Color of a Goober of Bacteria on a Piece of Filter Paper. Remember that given sufficient Time, a Goober of Oxidase Negative Bacteria flooded with the Blue Oxidase Reagent will eventually turn dark Blue. F Agar “Does this Bacterium produce fluorescent Siderophores?” You streaked your Gram Negative, Oxidase Positive Bacterium onto an F Agar Plate and incubated it at 30°C until Today’s Lab. • F Agar Positive (Pseudomonas ) The Bacterium secreted Water-soluble, fluorescent Siderophores to snarf-up any Iron that might be around. • F Agar Negative (See Note) The Bacterium did not secrete -- or was not capable of secreting -- Siderophores. It is so rare to encounter a Dud with F Agar that you’ll notice that we didn’t even bother with a Control here. Most of the Pseudomonas Strains we encounter secrete Siderophores by the Bucketful and you’ll be able to see the Fluorescence under the normal Lab Fluorescent Lights. We’ve got a UV Lightbox Set-Up in the Prep Area if you want to see the Fluorescence under UV Light. It really is neat. NOTE: If your Oxidase Positive Soil Isolate is F Agar Negative it does not automatically mean that it isn’t Pseudomonas . Most of the easily isolatable Strains of Pseudomonas produce fluorescent Siderophores; however, many Strains of Pseudomonas do not. Our Lab Standard Pseudomonas putida is always F Agar Positive.
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Lab 7 Page 17 IMViC Indole (Atlas Page 74) “Does this Bacterium have the Enzyme Tryptophanase?” You inoculated Chablis-colored Tryptone Broth with your Gram Negative, Oxidase Negative Bacteria and incubated these Tubes at 37°C for at least 48 Hours. • Indole Positive (E. coli ) The Bacterium has the Enzyme Tryptophanase and can break-down the Amino Acid Tryptophan into usable Goodies. Indole is a Side Product of this Reaction that can be detected by adding Kovac’s Reagent. Indole will react with the Kovac’s Reagent and form the Red Dye Rosindole, which will form a Magenta Ring at the Top of the Tube. The Blood-Red Dye Magenta was discovered the Day after a Battle was fought outside of the Town of Magenta in Northern Italy in 1859. • Indole Negative (Enterobacter ) The Bacterium does not have the Enzyme Tryptophanase. Indole will not be produced. Indole will not be present to react with Kovac’s Reagent. Rosindole will not be formed. There will be no Red Layer at the Top of the Tube. Methyl Red/Voges-Proskauer You’ll take each of your MR-VP Tubes (Stainless Steel Caps) and aliquot about Half of the Contents into new, labeled Tubes (Plastic Caps). You’ll use the Tubes with the Stainless Steel Caps for the Methyl Red Test and the Tubes with the Plastic Caps for the Voges-Proskauer Test.
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