Lab Report 2- positive gram stain

Lab Report 2- positive gram stain - Lab Report 2 Part 2...

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Lab Report 2: Part 2- Unknown Gram-Positive Madison Epting Section 12 October 16, 2016 This report represents my individual effort. I did not receive or offer aid to anyone when performing this assignment, nor did I plagiarize any material. Signed: __________________________________________________________
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Results Textual Summary: Gram-Positive An unknown culture of bacteria was given along with another unknown in two separate slants. The two unknown cultures were mixed together on a slide to gram stain. Fig. 1 shows the appearance of the mixed gram stain. A Gram-positive and Gram-negative stain both appeared on the mixed gram stain. The mixture of both bacterial cultures were placed onto three types of streak plates: PEA, MAC and a blood agar plate. The PEA plate shown in Fig. 3, cultivated Gram-positive bacteria and reduced growth in Gram-negative bacteria cells (1). This enabled a pure culture of positive bacteria cells to grow on the plate. The blood agar plate shown in Fig. 4 is the plate after 24 hours of incubation; the blood agar plate turned completely brown from its original red color. Since the PEA plate was selective for Gram-positive, the pure culture from the plate was put onto a slide and Gram stained another time to visualize the pure colony. The appearance of the unknown, Gram-positive pure colony can be seen in Fig. 2. Biochemical Tests In order to narrow down what the unknown Gram-positive bacteria could be, a series of 3 different biochemical tests were ran based on the morphology of the Gram- positive bacteria; this shape was found to be cocci. The 3 tests ran for the unknown Gram-negative bacteria was the Mannitol, Citrate, and the Catalase test. In Fig. 5 , the outcome of the mannitol test is shown. After incubating the unknown for 24 hours in a Durham tube. The culture had no color change nor bubbling inside the tube which resulted in a negative test. The citrate test in order to have a positive result had to turn blue after 24 hours of incubation. Fig. 6 shows a negative result considering the tube had no color change and remained a deep green color. The catalase test was conducted after 24 hours of incubation. This test contains a reagent called hydrogen peroxide,
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that when added, if bubbling occurs it is a positive test result. According to Fig. 7 , when adding the reagent, bubbling in the tube occurred resulting in a positive test outcome.
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