An unknown bacterium was handed out by the lab instructor. The methods that have been learned so far in identifying bacteria were applied to this unknown. Procedures were followed as stated in the lab manual and biochemical test handouts. The first procedure that was done was a gram stain followed by a streak of the unknown on a TSA plate in order to determine the gram reaction and observe the colony morphology. After that, specific biochemical tests were performed for gram positive, since unknown number five was determined to be gram positive rod. The other tests were performed in this order: Mannitol Salt (MSA) streak, Blood Agar streak, Catalase test, Nitrate Reduction test, and Phenyl Red Broth test for lactose and sucrose fermentation.
After performing a gram stain on unknown number five, number five was determined to be gram positive rod. On the TSA plate, number five had the following morphology: very large, raised, opaque cream color colonies that covered the entire plate and had beta-hemolysis. All the results from the biochemical tests performed are listed in Table 1 and are also shown in the preliminary (Figure 1) and final (Figure 2) flow charts that are included at the end of the lab report.
Table 1: Results from Biochemical Tests
Test Results Interpretations
Mannitol Salt (MSA)
No growth Organism is not Staphylococcus
Clear zone around colonies Organism hemolyzes RBC's completely so its Beta-hemolysis
Catalase is present
Nitrate Reduction Turned red after addition of... [continues]
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