Microorganism Lab Report

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A thorough analysis of a microorganism is an essential procedure that is done to identify the unknown species of bacteria. The correct identification is important in many aspects: so the right treatment is prescribed to a patient; in controlling and preventing disease outbreaks, and in laboratory studies. In this experiment, a series of tests were conducted to narrow down and identify the unknown bacteria. In the first step of identification, a sample of bacterial culture was used from the tube labeled #17 to perform a Gram stain test. As controls, Staphylococcus aureus, gram-positive cocci that stain purple, and Escherichia coli, gram-negative bacilli that stain pink, were stained on the same slide. The result of the Gram stain showed that…show more content…
coli. This step allowed to narrow the identification down to five possible bacteria: Enterococcus faecalis (E. faecalis), Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis), Micrococcus luteus (M. luteus), and Streptococcus pyogenes (S. pyogenes). The second step in identification was streaking a tryptic soy agar plate with the liquid culture of the unknown bacteria. This was done in order to grow bacteria for the use in subsequent tests and to isolate the colonies. The streak plate was placed in an incubator at 37°C. After 24 hours in incubator, the growth of round yellow colonies of bacteria was observed on a streak plate. The rest of the tests were set up according to a dichotomous key. Since unknown bacteria were Gram-positive cocci, the next procedure to perform was differential Blood Agar test. A plate with blood agar media was inoculated with the unknown and placed into the incubator at 37°C to see the if bacteria can utilize the blood and also to observe the pigment of the growth. After 72 hours, the plate was checked and the results indicated that bacteria produced yellow growth and tested negative for hemolysis. This result not only pointed to three possible choices of bacteria: E. faecalis, S.

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