The Starch Test Of Starch

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Starch
Only the Gram positive organisms were put through the starch test, as testing the Gram negative organisms would not have helped with identifying the unknown organism. Proper inoculation techniques were used to transfer the Gram positive organisms onto the starch plate in a straight line, and then the plate was incubated. The following week, after incubation, the plate was flooded with Gram’s iodine and was left to sit for ten minutes. Gram’s iodine indicated the presence of starch by forming a starch iodine complex that turns blue-brown or black. After pouring the excess iodine off, the plate was set on a white paper to analyze. A positive test with amylase present would present itself with a halo of clearing around the cell
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Citrate-negative cultures would also show no growth in the medium.
Urease
The urease test was not available, so students asked the lab TA for urease test results for their respective organisms.
Results
Gram Stain After Gram staining, organism A was classified as a Gram positive organism. On the other hand, organism B was classified as a Gram negative organism. After this, the two organisms were separated into their own flow charts. These results allowed for the strategic planning of tests of the Gram positive and Gram negative organisms to further identify them.
Fermentation
Organism A was tested positive for both glucose and lactose. Organism B was determined to be positive for glucose, but was tested negative for sucrose. The sucrose test significantly narrowed down the possible organisms for organism B. However, all the fermentation test results proved to be useful in eliminating possible organisms while confirming the correct identification of the two organisms.
Starch
Organism A was tested to be negative for the starch. This information helped in eliminating some possible options for the identification of the unknown.
Casein
Organism A tested to be negative for casein, which solely eliminated Micrococcus luteus as an option. Organism B tested to be positive, which eliminated some possible options for the unknown organism.
Catalase
Organism A was tested to be positive for the catalase,
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