Gram Positive And Gram-Positive Bacteria

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Gram-negative and Gram-positive bacteria can be distinguished by conducting biochemical tests. Its growth can be examined on selected mediums containing metabolic inhibitors such as antibiotics. The medias utilized in this project are: media containing the antibiotic vancomycin, Eosin Methylene Blue-lactose (EMB-lactose) agar, and Phenylethyl alcohol (PEA) agar (Holbrook and Leicht 2017). Vancomycin is most effective at inhibiting the growth of Gram-positive cocci (Rotschafer et al. 2005). EMB-lactose agar inhibits the growth of many Gram-positive bacteria and the lactose component of the medium allows for lactose-fermenting bacteria to cause color changes within the medium (Reynolds 2011). The presence of lactose fermenters in the EMB-lactose agar will cause a color change in the resulting colonies based on the strength of their acidity. A metallic green colony indicates that that active fermenters are present. A pink colony indicates that weak fermenters are present. If a bacterial species does not ferment lactose, it will appear white or colorless (Holbrook and Leicht 2017). PEA agar is a selective medium that inhibits the growth of most Gram-negative bacteria species. It does so by interrupting the lipids within the Gram-negative cell membrane, which will affect its permeability to certain molecules. This could result in the intake of materials that are supposed to be blocked and the release of potassium from within the cell, which is necessary for DNA synthesis (Lal and
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