Gram Check For Purity : Samples Essay

1224 Words Nov 2nd, 2015 5 Pages
Gram check for purity The first step to the unknown is selecting an actual organism. The best way to select a culture is based on a high-quality distribution. Equally important, shaking up the broth tube facilitates in the distribution. Upon selection, a gram check for purity is performed. Step by step instructions for this procedure can be found in Benson’s, Microbiological Applications p. 99. Furthermore, an aseptic technique must be performed for this test and the entire tests following the unknown. The purpose of this test is to differentiate between gram positive and gram-negative bacteria. The key indicator of gram-positive bacteria is a purple stain and a pink stain for gram-negative bacteria. A slide is viewed with a microscope under oil immersion. Equally significant, are the shape and arrangements of the bacteria. Without a doubt, maintaining a pure culture is the most critical piece. You want to avoid contamination of your culture. A gram-check is done every time before every inoculation or tests are performed, so you assure accurate results. Working and reserve stocks These stocks are completed on two separate TSA slants. One TSA will be a working slant utilized for that lab session. Next, make a fresh culture slant. A new working is used each lab. The reserve stock is refrigerated for 10 days in case of contamination. Next, incubate at 25 degrees Celsius. Immediately after incubation, evaluate for form, opacity, color, and amount of growth. Note all…

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