Unknown Microbiology Lab Report Essay

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The purpose of this lab was to identify two unknown bacteria from a mixed culture. The reason for identification of unknown bacteria was to help students recognize different bacteria through different biochemical tests and characteristics. This is important in the medical field because identification of unknown bacteria can help treat a patient by knowing the contributing source of a disease. Also knowledge of different bacteria helped others make antibiotics used today. This lab was completed by using the methods learned thus far in identification of bacteria.

Materials and Methods

A mixed culture of two unknown bacteria was provided by the instructor. The methods used for
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The colonies were smooth, translucent, and had a white brownish color. The Gram stain resulted in Gram positive cocci. After the Gram stain was completed, the bacteria were streaked on a Mannitol-Salt Agar plate and a Catalase test was performed. After these test were completed a Phenol Red Dextrose Fermentation tube was inoculated, and a SIM Tube inoculated.

The Unknown Bacteria 36/Bacteria # 2 on a TSA plate was examined by the naked eye and under a dissecting microscope. Bacteria # 2 was approximately 3 - 4 mm in diameter. They were circular in form with an entire margin and a flat elevation. The colonies were rough (granular), translucent, and white brownish color with black granules. The Gram stain resulted in a Gram negative rod. After the Gram stain was completed, the bacteria were streaked on an Eosin -Methylene Blue Agar plate and an Enterotube II was inoculated.

See Table 1 and Flow Chart 1 for results of Bacteria # 1 and Table 2 and Flow Chart 2 for results of Bacteria # 2.
Table 1: Biochemical Test Results (Bacteria # 1) TEST | PURPOSE | REAGENTS | OBSERVATIONS | RESULTS | Gram Stain | To determine the Gram reaction of Bacteria #1 | Crystal violet, Iodine, Alcohol, Safranin | Purple cocci | Gram positive cocci | MSA Agar plate | To determine Gram positive Staphylococcus species | None | Yellow halo around streak | Staphylococcus aureus | Catalase Test | To verify bacteria identification | Hydrogen peroxide | No bubbling |
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