Grain Staining Essay

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The purpose of exercise 4 was to understand the differential staining techniques: gram staining and special stain structures. Differential staining techniques are used to help identify microorganisms based on the morphology and its ability to accept the stains used. During the staining process the cells retaining the initial stain are positive, and the cells retaining the counter or secondary stain are considered to be negative. Differential stains are used to identify microorganism based on metabolism, chemical composition or the presence of another structure. The staining techniques that are used in microbiology labs are essential in identification of the organism.

We had prepared heat fixed slides before the
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The endospore made in response to adverse conditions for survival. The bacteria will produce an endospore to germinate when the conditions improve for survival. The endospore stain technique uses a steam process to allow the initial stain of malachite green to penetrate the tough out portion of the spore, the initial stain is washed off and a counterstain of Safranin is used as a secondary stain. The final diagnostic test in this exercise is motility media. This test checks for the presence of flagella in the culture. TCC is added to the media, this allows the bacteria to be viewed in the media when it has moved across the media. When it is metabolized the TCC changes from being colorless to a pink color. Three test tubes were inoculated with E. coli, P. aeruginosa, and S. epidermidis. Three test tubes of motility media were inoculated by aseptic techniques and a sterile inoculation needle was used to culture the broth. The needle was placed straight down in the motility media and pulled straight up. The tube and needle were fired as part of aseptic techniques. The test tubes where allowed placed in an incubator and observed 48 hours later.

For this exercise we heat fixed 9 slides labeling the slides A-I, and began the staining processes. All slides were observed by oil immersion lens after the appropriate staining techniques to view the differences in the morphology, size, arrangements and the outcome of the staining techniques.

The Gram staining

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