Unknown Lab Report

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Introduction After collecting a random air sample on an agar plate, the objective was to identify an unknown bacterium through a series of carefully executed metabolic tests. Not only was this to provide students with how to characterize an unknown sample but also it was a learning experience with every different test. Each experiment provided a new result gaining a step closer to identifying what the unknown was. The goal at the end was to have enough results and data to accurately determine what the sample might be. After a series of test, the result was Staphylococcus epidermis, a facultative anaerobic bacterium that is most likely found on human skin. Staphylococcus epidermis is not known to be the cause of most common infectious diseases but strangely is most likely to cause most “hospital environment born” infections (MLST). A recent study has found that the bacterium can also cause…show more content…
A positive result for this test meant that it could produce the enzyme, catalase, that is mainly found in aerobic bacteria. When observing for what the bacteria produced when introduced to glucose, it grew and produced gas as well as a color change. This reaction meant that it could utilize and while it fermented the sugar it also produces a gas. In the nitrate reduction, the bacteria produced a gas after being inoculated in nitrate broth. This positive result meant that the bacteria could reduce nitrates to nitrites. After using the flow chart to determine the unknown substance, there might have been a more accurate choice than Staphylococcus epidermis. One obvious characteristic that this bacteria has is that it is an off white color, which is not accurate to the description when it was present on the agar plate. This bacteria was a very pigmented gold-yellow, which seems to be more likely Staphylococcus aureus. This bacterium is also Voges-Proskauer positive, which Staphylococcus epidermis was not.

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