Conclusion Of Indole Test

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Discussion: Each test is a pertinent contribution to drawing an educated conclusion. After performing the gram staining and observing which unknown culture was gram positive, a catalase test was performed. The catalase test allows lab workers to differentiate Staphylococci and Streptococci genus. The test was performed only on the gram-positive culture. Bacteria that respire by the use of oxygen, otherwise known as aerobic respiration, produce enzyme or “catalase”. This protects the bacteria from the harmful by-product produced from oxygen metabolism that would normally be bactericidal. A positive reaction here would present visible bubbling. A negative reaction would be no reaction or no bubbles produced. Due to no bubbles being produced this leads us to our next set of tests to perform on the unknown. With this knowledge of a negative catalase test …show more content…
This is done by the enzyme tryptophanase. The indole test is used to determine if the bacteria is the indole positive Escherichia coli or one of the indole negative bacterium Enterobacter or Klebsiella. This is a good test to perform specifically because it either tells you which bacterium you have or that you need to perform more tests to determine which of the other two other genus it could be. Post 37o Celsius incubation, students are to add kovac’s or Ehrlich’s reagent to the culture. Theses reagents react with indole to produce a red coloured compound. With no indole present there is no color change even after the addition of the appropriate reagent. Observing the gram negative bacteria in the tryptone test tube with addition of the appropriate reagent shows no change in color which is indicative of there being no indole present in the media. These are the expected results of a negative indole test narrowing our genus options now to two potential

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