What is EMB agar used for?
Eosin methylene blue agar (EMB) is a selective and differential medium used to isolate fecal coliforms. Eosin Y and methylene blue are pH indicator dyes which combine to form a dark purple precipitate at low pH; they also serve to inhibit the growth of most Gram positive organisms.
How EMB media differentiate bacteria?
Differentiation of enteric bacteria is possible due to the presence of the sugars lactose and sucrose in the EMB agar and the ability of certain bacteria to ferment the lactose in the medium. This metallic green sheen is an indicator of vigorous lactose and/or sucrose fermentation ability typical of fecal coliforms.
What bacteria grows on EMB Agar?
Some gram-positive bacteria, such as enterococci, staphylococci, and yeast will grow on this medium and usually form pinpoint colonies. Non-pathogenic, non-lactose-fermenting organisms will also grow on this medium.
What kind of media is blood agar?
Blood agar is an enriched, bacterial growth medium. Fastidious organisms, such as streptococci, do not grow well on ordinary growth media but grow on blood agar. Blood agar is a type of growth medium with trypticase soy agar base enriched with 5% sheep blood.
Is E. coli gram positive?
Escherichia Coli is a Common Intestinal Bacteria. E. coli is a Gram negative anaerobic, rod-shaped, coliform bacteria of the genus Escherichia, commonly found in the lower intestine of humans and animals.
Is E. coli lactose fermenting?
Background. E. coli are facultative anaerobic, Gram-negative bacilli that will ferment lactose to produce hydrogen sulfide. Up to 10% of isolates have historically been reported to be slow or non-lactose fermenting, though clinical differences are unknown.
Why is E. coli green on EMB agar?
On EMB if E. coli is grown it will give a distinctive metallic green sheen (due to the metachromatic properties of the dyes, E. coli movement using flagella, and strong acid end-products of fermentation). Some species of Citrobacter and Enterobacter will also react this way to EMB.
What types of bacteria grow on EMB agar?
Some strains of Salmonella and Shigella may fail to grow on EMB Agar. Some gram-positive bacteria, such as enterococci, staphylococci, and yeast will grow on this medium and usually form pinpoint colonies. Non-pathogenic, non-lactose-fermenting organisms will also grow on this medium.
What does EMB agar test for?
EMB agar is used in water quality tests to distinguish coliforms and fecal coliforms that signal possible pathogenic microorganism contamination in water samples (presence of E.coli in the river/water sample indicates possibility of fecal contamination of water so does the presence of other pathogenic enterics).
Is EMB agar selective or differential or both?
EMB Agar: Composition, uses and colony characteristics. Eosin Methylene Blue (EMB) agar is a both selective and differential culture medium. It is selective culture medium for Gram-negative bacteria (selects against Gram positive bacteria) and is commonly used for the isolation and differentiation of coliforms and fecal coliforms.
What type of bacteria does EMB agar favor?
EMB agar is a selective culture medium for Gram-negative bacteria. It is primarily used for isolation and differentiation of lactose fermenting (forms coloured colonies) and non-lactose fermenting (form colourless colonies) enteric bacilli.