Catalase Test Lab Report

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During the first lab period, The gram stain show that the unknown bacteria was a gram neative rod shaped microbe. After this step was established, this next part was to select the best tests and mediums to determine the unknown bacteria.This medium are use to test the metabolic characteristics of the unknown bacteria. In order to identify the unknown bacteria from other bacterias the following medium was used: MSA plate, SIM plate, nitrate reduction test Nutrient gelatin and Urease broth. For Metabolic tests, only Catalase test were performed on the unknown bacteria. These tests were best use gram negative bacteria to indicated what the unknown microbe is.
For the Catalase test, the use of hydrogen preoxide on the sample of the unknown
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The three medium are sulfur reduction, indole production and motility. For sufur reduction, the unknown bacteria was able to reduce sulfur to hydrogen sulfide. There was a positive result for this part of the test. There were black precipitate which is a sign for a positive result. For motililty, It also test positive by the cloudy red result of the medium. The last part of the test is indole. This test the microoganism be able to produce tryptochan . The bacteria also test positive for this part of the medium.For the urease broth medium, the bacteria test positive for urease. The positive result is when the organism turn pink. The pH indictor for this test is phenol red. Phenol red turn yellow in a acidic enviroment and pink is alkaline enviornment. This test is useful for enterics bacteria like the genus Proteus.

Unknown bacteria #20 has the following results: Catalase positive, MSA negative, Nutrient gelatin negative, nitrate reduction positive, SIM positive, and Urease positive. After review these results, the unknown was determing to be Proteus. Vulgaris. The tests that help confirm the result was SIM medium , nitrate reduction meduim and urease broth. After research the internet for the reason why gelatin test was negative, Proteus vulgaris take a long time to break down gelatin. Therefore the test was a negative because there was not enough time for it to become a

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