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.
Levine eosin methylene blue agar does not contain lactose. It is a selective and differential medium used for the isolation and differentiation of gram-negative enteric bacteria based on their ability to ferment lactose. The agar contains lactose as a substrate for fermentation, but the actual quantity of lactose present in the agar may vary depending on the manufacturer and the specific formulation of the medium.
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.
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.
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.
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 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.
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.
So here is the deal, same use different recipies different results to do the same thing. I'll just post some lecture notes and hope that helps:MacConkey's Agar (enterics)Selective for gram negativeCrystal violet and bile salts prevent non-entericsDifferential for lactose fermentationNon-fermenter --> white/clear coloniesFermenter--> red/pink coloniesEosin Methylene Blue (EMB) (Weakly selective for intestinal pathogens)Selective for gram negativeEosin and methylene blue inhibit gram positive growthDifferential for lactose fermentationLactose fermenters produce a green-metallic sheenNon-fermenters do notNOTE: EMB Agar is not in common use anymore
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.
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.
EMB agar is a complex undefined medium because it contains multiple components such as peptone, lactose, agar, and eosin Y and methylene blue dyes that promote the growth of a wide variety of bacteria while inhibiting the growth of certain Gram-positive bacteria.