Unknown Bacteria Lab Report

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The goal of the experiment was to determine a bacterial colony grown from a sample by using biochemical and cellular tests. These tests determined many of the unknown bacteria’s characteristics. The appearance of strings during the KOH test indicates that the bacteria is gram negative as it means the cell had lysed. This result was not backed up with the results of the test media. The bacteria only grew PEA, which indicate the unknown is gram positive. The conclusion was drawn the the KOH test was a false positive as too much culture was used; a common mistake resulting in false positives. With the determination of the bacteria being that of gram positive, two more tests were performed to further differentiate between possible gram positive bacteria. During the catalase test, the immediate formation of bubbles indicates that the bacteria contains high levels of catalase. The bacteria did grow on the mannitol salt agar plate, indicating that the bacteria is resistant to sodium chloride. The agar also appeared red meaning that the bacteria was unable to ferment the mannitol.
With these results, it is possible to make a guess of what kind of bacteria the unknown was. With the bacteria being gram positive and catalase positive it suggests the bacteria is a Bacillus, Staphylococcus,
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Bacillus Stratosphericus is a strain of bacteria that is often found high in the atmosphere, it can be found upwards of 40 km, but can be found on the ground. Bacillus Stratosphericus are rod shaped (bacilli), gram and catalase positive, and can survive in salt concentrations up to 11%, indicating it could grow on an MSA plate (Shivaji et al 2006). These characteristics are mostly consistent with the lab results. The one inconsistency is the shape of bacteria. This can likely be attributed to human error as even with a microscope it is still difficult to determine the shape of a