Gram Catalase Test Report

The objective of these series of experiments was to identify two unknown bacteria’s. Broth culture #20 was selected and subjected to qualitative tests for identification. Gram stain tests were performed in order to identify which unknown is gram positive and gram negative. Using selective and differential media, like MacConkey agar which allows the growth of gram negative bacteria only that are able to ferment lactose. Also, mannitol agar was used which isolates and detects gram-positive bacteria. As well as blood agar, which is a nutritive media with differential properties in respect to hemolysis. The catalase test indicated catalase production and the coagulase test indicated a lack clotting in the tube. These tests were used for
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The reasons range from diagnosing a disease in a patient, so as to know how it can be handled and treated, to knowing the appropriate microorganism to be used for making certain foods or antibiotics. Also, it can lead to many new discoveries such as new species or evolution of new species. This study is done by applying all of the methods and techniques that have been learned and used in the microbiology laboratory for the identification of the unknown bacteria’s.
In this experiment, multiple of tests were conducted to provide the fermentation abilities, existence of specific enzymes, and certain biochemical reactions. Observations obtained from the tests were compared to the unknown bacteria identification key help with the identification process.
Various steps are involved in the identification of the unknown bacteria. The first step is the isolation. As the broth culture contains a mixture of bacteria, the importance of this test was to isolate the pure colonies of the bacteria present. Streaking the bacteria is the most efficient method for obtaining pure colonies. The bacteria are introduced to the media, by inoculating it on the surface of the solid agar plate with the inoculation loop. This results in making a dilution gradient across the agar plate, in which after incubation; individual colonies will arise from the biomass. Characteristic features such as size, shape, colour, margin,
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It is also called differential staining because it differentiates among bacteria and can be used to distinguish between them based on the differences of cell wall structure. There are two major groups of bacteria, the gram positive staining cells and gram negative staining cells. In this procedure, the bacteria are first stained with crystal violet “basic stain”, and then treated with adding a mordant, iodine, which fixes the stain inside the cell. The stained cells are washed with a decolorizing agent, alcohol and then counterstained with

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