Lab Report 2- Negative Unknown

Lab Report 2- Negative Unknown - Lab Report 2 Part 1...

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Lab Report 2: Part 1- Unknown Gram-Negative 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-Negative 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 into threes types of streak plates: PEA, MAC and a blood agar plate. The outcome of the MAC plate, showed in Fig. 3, proved that the Gram-negative was not a lactose fermenter. 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 MAC was selective for Gram-negative, the bacteria from this plate was put onto a slide and Gram stained another time to visualize the pure colony. The appearance of the unknown, Gram-negative pure colony can be seen in Fig. 2. In order to narrow down what the unknown Gram-negative bacteria could be, a series of 4 different biochemical tests were ran based on the morphology of the Gram- negative bacteria; this shape was found to be bacilli. The 4 tests ran for the unknown Gram-negative bacteria was the Indole, H 2 S production, and the MR-VP test. In Fig. 5 , the outcome of the indole test is shown. After incubating the unknown for 24 hours, and adding 12 drops of Kovac’s reagent to the culture, the indole test had a negative result. The H 2 S test in Fig. 6 produced a black color inside the tube; meaning the unknown Gram-negative isolate had a positive result for H 2 S production. The MR-VP test was conducted in separate tubes. One was the Methyl red test (MR) and the other was the Voges-Proskauer test (VP). The MR test concluded that after adding 4 drops of methyl red (shown in Fig. 7) the culture had a red color change immediately
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which is a positive result. In Fig 8, the VP test showed that no color change occurred after the reagents were added, which resulted in a negative test result. Discussion/ Identifying Unknown Gram-Stain The Gram-Staining process provided a way to know which of the two unknown cultures was positive and which was negative. Given that the negative were pink bacilli, this aided in finding a starting point for the unknown bacteria.
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