Quick Answer: What Is Differential Agar?

Why is MacConkey agar selective as well as differential?

MacConkey agar is an example of a medium that is both differential and selective.

The presence of bile salts, as well as crystal violet, within the media prevent gram-positive organisms from growing..

What is the indicator in blood agar?

Phenol red is the pH indicator. Motility-Indole-Ornithine Agar: motility is indicated by the character of the growth in the butt of this tube.

Is blood agar enriched or differential?

Blood agar is one type of differential medium, allowing bacteria to be distinguished by the type of hemolysis produced.

What are the differential media?

Differential media contain compounds that allow groups of microorganisms to be visually distinguished by the appearance of the colony or the surrounding media, usually on the basis of some biochemical difference between the two groups.

What is blood agar differential for?

Blood agar is a differential medium that distinguishes bacterial species by their ability to break down the red blood cells included in the media. Blood agar is often used to distinguish between the different species of pathogenic Streptococcus bacteria.

How do you prepare blood agar?

Preparation of Blood AgarSuspend 28 g of nutrient agar powder in 1 litre of distilled water.Heat this mixture while stirring to fully dissolve all components.Autoclave the dissolved mixture at 121 degrees Celsius for 15 minutes.Once the nutrient agar has been autoclaved, allow it to cool but not solidify.More items…•

What is the difference between blood agar and chocolate agar?

The composition of chocolate agar and the Blood Agar is the same and the only difference is while preparing chocolate agar, the red blood cells are lysed. … Neither of these species is able to grow on sheep blood agar. Chocolate agar slants are used for the short-term storage of pathogens such as N.

Is chocolate agar a differential?

Chocolate agar, a differential medium for gram-positive cocci.

What type 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. Blood agar is a type of growth medium (trypticase soy agar enriched with 5% sheep blood) that encourages the growth of bacteria, such as streptococci, that otherwise wouldn’t grow.

What type of medium is MacConkey Agar?

MacConkey agar (MAC) is a bacterial culture medium named after bacteriologist Alfred T. MacConkey (1861-1931). MacConkey agar is a selective and differentiating agar that only grows gram-negative bacterial species; it can further differentiate the gram-negative organisms based on their lactose metabolism.

Is EMB Agar selective or differential?

EMB is a selective, differential agar medium used for isolation of gram negative rods in a variety of specimen types.

Is XLD agar selective or differential?

Principle of XLD Agar XLD Agar is both a selective and differential medium. The medium contains yeast extract, which provides nitrogen and vitamins required for growth. It utilizes sodium deoxycholate as the selective agent and, therefore, is inhibitory to gram-positive micro-organisms.

What type of medium is chocolate agar?

Chocolate agar (CHOC) or chocolate blood agar (CBA), is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating to 80°C.

What is the difference between differential and selective media?

Selective media generally selects for the growth of a desired organism, stopping the growth of or altogether killing non-desired organisms. Differential media takes advantage of biochemical properties of target organisms, often leading to a visible change when growth of target organisms are present.

Is Cled agar selective or differential?

CLED Agar is a differential culture medium for use in isolating and enumerating bacteria in urine. MacConkey II Agar is a selective and differential medium for the isolation and differentiation of Enterobacteriaceae and a variety of other gram-negative rods from clinical and non-clinical specimens.

Can a media be both selective and differential?

Selective and differential media can be combined and play an important role in the identification of bacteria by biochemical methods. Another commonly used medium that is both selective and differential is eosin-methylene blue (EMB) agar. … Therefore, EMB is selective for gram-negatives.

What is the purpose of differential media?

Differential media are bacteriological growth media that contain specific ingredients to allow one to distinguish selected species or categories of bacteria by visual observation. Differential Media are used to distinguish between closely related organisms or groups of organisms.

Can bacteria grow in chocolate?

The pulp surrounding the cocoa beans is fermented by various microbes including yeasts, lactic acid bacteria, and acetic acid bacteria. … The beans inside of the cocoa pods are in an environment such that no microbes can grow.