7 Would removing eosin Y andlor methylene biue from EMBaar ater the medum\'s sen
ID: 212705 • Letter: 7
Question
7 Would removing eosin Y andlor methylene biue from EMBaar ater the medum's sensitivity or specificity? Explain your answer.(See pages 8 and 9, "A Word About Experimental Design," for assistance with these 8 Suppose a mistake is made in preparing a batch of EMB agar and the starting pH is 7.6 instead of Would that affect the medium's sens About Experimental Design," for assistance with these terms.) itivity or specificity? Explain your answer. (See pages 8 and 9, "A Word 9 Compare the recipes of nutrient agar and EMB agar. If an organism can grow on both media, on which would you expect it to grow better? Explain your answerExplanation / Answer
1, eosin Y and methylene blue in EMB agar play a crucial role in the medium as they inhibit the growth of Gram-Positive organisms and react with vigorous lactose fermenters and turn growth dark purple to black.
Removal of one or both of these would alter specificity because organisms that are not supposed to grow on EMB would, and some of those might be able to ferment lactose to acid end products. It will also alter sensitivity. but still, probably we will be able to detect growth of organisms that generally grows on EMB. the ability to detect colour changes connected with lactose fermentation would be lost or hampered, depending on whether both or only one are removed.
2. Sensitivity will acquire false negatives. since We are looking for a colour change due to acid generation from lactose fermentation. If we start at a higher pH, more alkaline, then it will take longer (more acid) to change the colour.
3.It would presumably grow better on NA, which has a beef extract that is a rich mix of biochemicals and peptone. EMB supplies one carbohydrate and one protein derivative (gelatin) for carbon and nitrogen sources.
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