A Series Of Biochemical Tests

3673 WordsApr 15, 201515 Pages
A series of biochemical tests were conducted in order to determine the identity of an unknown gram negative bacterium. The unknown had the potential to be one of six different gram negative bacteria: Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumonia, or Salmonella typhirmurium. After using the T-streak method to isolate pure colonies and confirming the gram negative nature of the unknown bacterium the unknown was subjected to seven biochemical tests and the results compared to the results of the six known bacteria for the same tests. After performing the Triple Sugar Iron Agar Test, Sulfur Indole Motility Test, Methyl Red Test, Voges-Proskauer Test, Citrate Test, Urease Test, and Gelatin Test it was confirmed that identity of Unknown #15 was Salmonella typhirmurium. While all bacteria retain basic qualities identifying them as prokaryotes they do not function, grow, or even metabolize in the same way. These differences distinguish bacterial species from one another, like a thumb print identifies a single individual from every other person on earth. Testing for these unique factors through a series of biochemical tests and staining techniques allows for an unknown bacterial strain’s “thumb print” to be generated. From there the unknown’s thumb print can be compared to the thumb print of known bacterial species allowing for identification. The first step in identification is performing a Gram Stain. Due to the fact
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