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EMB agar is used for the selective and differential isolation of fecal coliforms, particularly Escherichia coli, in water, milk, and other biological material. It contains lactose, eosin, and methylene blue dyes that inhibit the growth of Gram-positive bacteria and help differentiate lactose fermenters (such as E. coli) that produce dark colonies with a greenish metallic sheen.
Eosin Methylene Blue Agar (EMB) was developed by Holt-Harris and Teague.1 This formula contains lactose and sucrose with two indicator dyes, Eosin Y and Methylene Blue. The use of Eosin Y and Methylene Blue as indicators produced sharp and distinct differentiation between colonies of lactose fermenting and nonfermenting organisms. Sucrose is included to detect coliforms that ferment sucrose more readily than lactose. EMB Agar is selective due to the presence of an inhibitor and differential based on the ability of some organisms to ferment carbohydrates with the absorption of an Eosin Y and Methylene Blue complex.
Eosin methylene blue (EMB) agar is selective for gram-negative bacteria, especially those that can ferment lactose. Common bacteria that grow on EMB agar include Escherichia coli and Enterobacter aerogenes. These bacteria are differentiated by their ability to ferment lactose, producing colonies that are metallic green or dark purple on EMB agar.
Eosin methylene Blue Agar contains peptone (a sugar of glucose), lactose, sucrose, and the dyes eosin Y and methylene blue. The sugars provide fermentable substrates to encourage growth of fecal coliforms. The dyes inhibit growth of Gram-positive organisms.
Bile salts in Eosin Methylene Blue agar inhibit the growth of Gram-positive bacteria, allowing for the selective growth of Gram-negative bacteria. This helps in the detection and differentiation of organisms based on their ability to ferment lactose and produce acid.
blue bacilli
Eosin methylene blue agar is a selective and differential agar used for the isolation and differentiation of gram-negative bacteria. Eosin Y and methylene blue dyes inhibit the growth of gram-positive bacteria, while lactose fermentation by some gram-negative bacteria leads to the formation of pink or purple colonies. Additionally, the agar can distinguish between lactose fermenters and non-fermenters based on colony color and appearance.
Spirit blue agar contains peptone, yeast extract, lactose, agar, and spirit blue dye. The dye is added to visualize the digestion of lactose by bacteria, allowing for the differentiation of lactose-fermenting and non-fermenting organisms.
Simmons citrate agar is a differential agar used to determine if a sample bacteria can utilize citrate as its only carbon source. The agar is initially a green color due to the bromo thymol blue pH indicator in it. If a bacteria uses the citrate, the by-products are ammonia and ammonium hydroxide both of which will alkalize the agar and increase the pH to the point of changing the indicator's color to blue, so the whole agar turns from green to blue.
EMB agar is used for the selective and differential isolation of fecal coliforms, particularly Escherichia coli, in water, milk, and other biological material. It contains lactose, eosin, and methylene blue dyes that inhibit the growth of Gram-positive bacteria and help differentiate lactose fermenters (such as E. coli) that produce dark colonies with a greenish metallic sheen.
EMB agar is useful for the selective isolation of gram-negative bacteria, especially fecal coliforms such as E. coli, from clinical and environmental samples. It is also helpful in differentiating lactose-fermenting bacteria (which produce dark colonies with green metallic sheen) from non-lactose fermenters based on colony color and appearance.
Coliforms can be recognized on desoxycholate agar by their ability to ferment lactose, resulting in red to pink colonies due to acid production. On eosin methylene blue (EMB) agar, coliforms typically produce colonies that are pink to purple, with some strains exhibiting a metallic green sheen due to strong lactose fermentation. Both media suppress the growth of non-coliforms, allowing for clearer identification of coliform bacteria.
Eosin Methylene Blue Agar (EMB) was developed by Holt-Harris and Teague.1 This formula contains lactose and sucrose with two indicator dyes, Eosin Y and Methylene Blue. The use of Eosin Y and Methylene Blue as indicators produced sharp and distinct differentiation between colonies of lactose fermenting and nonfermenting organisms. Sucrose is included to detect coliforms that ferment sucrose more readily than lactose. EMB Agar is selective due to the presence of an inhibitor and differential based on the ability of some organisms to ferment carbohydrates with the absorption of an Eosin Y and Methylene Blue complex.
Eosin methylene blue (EMB) agar is selective for gram-negative bacteria, especially those that can ferment lactose. Common bacteria that grow on EMB agar include Escherichia coli and Enterobacter aerogenes. These bacteria are differentiated by their ability to ferment lactose, producing colonies that are metallic green or dark purple on EMB agar.
Another organism on the starch agar plate breaks down the starch into smaller sugars, and the starch intolerant organism in turn competes for the smaller sugars. As a result, you will see colonies of the starch user pop up first, and then smaller satellite colonies of the dependant organism will form around them.
Eosin methylene Blue Agar contains peptone (a sugar of glucose), lactose, sucrose, and the dyes eosin Y and methylene blue. The sugars provide fermentable substrates to encourage growth of fecal coliforms. The dyes inhibit growth of Gram-positive organisms.
Bile salts in Eosin Methylene Blue agar inhibit the growth of Gram-positive bacteria, allowing for the selective growth of Gram-negative bacteria. This helps in the detection and differentiation of organisms based on their ability to ferment lactose and produce acid.