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Applying The Methyl Red (Mr) Test

1196 words - 5 pages

The MR test media contains peptone, glucose, and a phosphate buffer (Stout et al, 45). To perform the MR test, I used the stabbing technique to inoculate the MR media. I sterilized the stabbing utensil under an open flame, obtained a small amount of unknown bacteria, and stabbed the MR media. Once the MR media was inoculated, I let it incubate for 24 hours in the 37°C hot room. After the 24-hour incubation, I added 15 drops of Methyl Red to the MR media to test for mixed acid production.
VP test (a.k.a. butanediol fermentation test) contains peptone, glucose, and a phosphate buffer in its media, which is the same media as the MR test (Stout et al, 47). To perform the VP test, I used the stabbing technique to inoculate the VP media. I sterilized the stabbing utensil under an open flame, obtained a small amount of unknown bacteria, and stabbed the VP media. Once the VP media was inoculated, I let it incubate for 24 hours in the 37°C hot room. After the 24-hour incubation, I added 15 drops of both Barrits Reagent A and Barrits Reagent B to the VP media, for a total of 30 drops.
The Citrate medium, a.k.a. Simmons Citrate Agar, contains sodium citrate as the sole carbon source and ammonium phosphate as the sole nitrogen source (Stout et al, 43). To perform the Citrate test, I used the stabbing technique to inoculate the Citrate media. I sterilized the stabbing utensil under an open flame, obtained a small amount of unknown bacteria, and stabbed the Citrate media. Once the Citrate media was inoculated, I let it incubate for 24 hours in the 37°C hot room. After the 24-hour incubation, I reviewed the Citrate media for a change in the PH of the media, which was indicated by a color change of blue or green.
The Urease test has a liquid media of Urea broth, which is a buffered solution of urea and yeast extract and it also contains a PH indicator (Stout et al, 47). To perform the Urease test, I used the streaking technique to inoculate the Urease broth. I sterilized the streaking loop under an open flame, obtained a small amount of unknown bacteria, and streaked the Urea broth over the entire surface. Once the Urea broth was inoculated, I let it incubate for 24 hours in the 37°C hot room. After the 24-hour incubation, I viewed the broth for any color change that would indicate the production of Urease.
The final test performed was the Gelatin test. The Gelatin medium is composed of gelatin, peptone, and beef extract (Stout et al, 44). To perform the Gelatin test, I used the stabbing technique to inoculate the Gelatin media. I sterilized the stabbing utensil under an open flame, obtained a small amount of unknown bacteria, and stabbed the Gelatin media. Once the Gelatin media was inoculated, I let it incubate for 8 days in the 37°C hot room. After the 8 day incubation, I put the Gelatin media into the 4°C “cold room” for one hour. After one hour I viewed the Gelatin test media for presence of gelatinase.
The TSIA test results after 24 hours was...

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