Mannitol Salt Agar Test

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Introduction The identification of a microorganism is not only vital in a microbiology lab, but also in the medical and pharmaceutical fields. Knowing the identity of a microorganism has helped diagnose numerous diseases, discover the source of the pathogen, and has provided patients with effective treatments such as antibiotics. In addition, the morphology of a bacterium and an arrangement of biochemical tests are utilized to identify an unknown bacterium. In this experiment, students performed biochemical test typically conducted in a research or clinical setting to determine an unknown bacterium. The purpose of this lab was to identify an unknown bacterium by using the methods that were studied in previous labs to acquire additional information about the unknown bacterium. Materials and Methods To limit the amount of errors or contamination in any procedure lab safety rules, gloves, and the aseptic technique was strictly enforced throughout the experiment. The first step to identifying the unknown bacterium was the Streak Plate Method. This method is used to isolate a pure culture from a mixed culture. Also, this method included streaking a…show more content…
The MSA is commonly known as a selective and differential growth medium for bacterium. The ingredients in this test were Mannitol, 7.5% of NaCl, and the pH indicator phenol red. In this experiment the Mannitol is the carbohydrate that provides the substrate for fermentation. Also, the sodium chloride allowed the medium to be selective and the pH indicated whether or not fermentation had taken place. The procedures for this test included: obtaining a sterile test tube of the phenol red and inoculating your unknown into the test tube by using a sterile loop. Next, you would incubate your experiment for 24 hours. A positive result of fermentation would depict a yellow pH color in the test tube, while a negative result of fermentation would depict no color

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