Question: What Is The Purpose Of MacConkey Agar Quizlet?

What color is MacConkey Agar?

Result Interpretation on MacConkey AgarOrganismsGrowth resultsEnterobacter, KlebsiellaMucoid, pink coloniesProteusColorless colonies, swarming growthSalmonella, ShigellaColorless colonies, or sometime medium color: orange to amberPseudomonasIrregular, colorless to pink colonies1 more row•Sep 18, 2018.

What is the purpose of blood agar?

Many species of bacteria produce toxic by-products that are capable of destroying red blood cells. Blood agar is a general purpose enriched medium often used to grow fastidious organisms and to differentiate bacteria based on their hemolytic properties.

What is an example of differential media?

Examples of differential media include: Blood agar (used in strep tests), which contains bovine heart blood that becomes transparent in the presence of hemolytic. … MacConkey (MCK), which is differential for lactose fermentationmannitol salt agar (MSA), which is differential for mannitol fermentation.

Do Gram positive bacteria grow on MacConkey Agar?

Gram-positive bacteria will not form any colonies on MacConkey medium.

How do you interpret MacConkey Agar?

Result Interpretation on MacConkey Agar Lactose fermenting strains grow as red or pink and may be surrounded by a zone of acid precipitated bile. The red colour is due to production of acid from lactose, absorption of neutral red and a subsequent colour change of the dye when the pH of medium falls below 6.8.

What types of bacteria are inhibited on MacConkey Agar?

MacConkey agar not only selects for Gram-negative organisms by inhibiting Gram-positive organisms and yeast but also differentiates the Gram-negative organisms by lactose fermentation.

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. Motile organisms will produce a general clouding of the medium or a fuzzy stab line.

What are the types of agar?

Types of agar platesBlood agar – contains blood cells from an animal (e.g. a sheep). … Chocolate agar – this contains lysed blood cells, and is used for growing fastidious (fussy) respiratory bacteria.Neomycin agar – contains the antibiotic neomycin.Sabouraud agar – used for fungi.More items…

What type of media is both selective and 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 purpose of MacConkey Agar?

MacConkey Agar (MAC) is a selective and differential medium designed to isolate and differentiate enterics based on their ability to ferment lactose. Bile salts and crystal violet inhibit the growth of Gram positive organisms. Lactose provides a source of fermentable carbohydrate, allowing for differentiation.

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.

Why is MacConkey agar used for E coli?

Sorbitol MacConkey agar is a variant of traditional MacConkey agar used in the detection of E. coli O157:H7. … This is important because gut bacteria, such as Escherichia coli, can typically ferment lactose, while important gut pathogens, such as Salmonella enterica and most shigellas are unable to ferment lactose.

What grows best on MacConkey Agar?

MacConkey’s is a selective medium that inhibits the growth of Gram-positive bacteria due to the presence of crystal violet and bile salts. Gram-negative bacteria grow well on MAC. … Clockwise from top left MacConkey’s, Mannitol Salt and Blood Agar.

Is blood agar selective or differential quizlet?

Terms in this set (14) Blood agar is Differential and enrich. Beta-hemolysis is complete hemolysis. It is characterized by a clear (transparent) zone surrounding the colonies.

What makes MacConkey selective and/or differential quizlet?

For what is MacConkey Agar selective and differential? Selective: for Gram-negative bacteria because bile salts and crystal violet inhibit the growth of Gram-positive bacteria. Differential: based on ability to ferment lactose (bacteria that can ferment lactose cause a drop in pH which turns indicator pink).

What ingredient makes MacConkey Agar differential?

lactoseThis medium is both selective and differential. The selective ingredients are the bile salts and the dye, crystal violet which inhibit the growth of Gram-positive bacteria. The differential ingredient is lactose.

What is the use of nutrient agar?

Nutrient agar is a general purpose medium supporting growth of a wide range of non-fastidious organisms. It typically contains (mass/volume): 0.5% Peptone – this provides organic nitrogen. 0.3% beef extract/yeast extract – the water-soluble content of these contribute vitamins, carbohydrates, nitrogen, and salts.

Is E coli Gram positive or negative?

Escherichia coli (commonly abbreviated E. coli) is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans.

Is MacConkey Agar defined?

MacConkey agar is an indicator, a selective and differential culture medium for bacteria designed to selectively isolate Gram-negative and enteric (normally found in the intestinal tract) bacilli and differentiate them based on lactose fermentation.

What is the difference between EMB agar and MacConkey Agar?

An example of a selective medium is MacConkey agar. It contains bile salts and crystal violet, which interfere with the growth of many gram-positive bacteria and favor the growth of gram-negative bacteria. … EMB contains the dyes eosin and methylene blue that inhibit the growth of gram-positve bacteria.

What does E coli look like on MacConkey Agar?

coli was made based on its characteristic morphology colony on the selective medium MacConkey agar. Rapid lactose fermenting colonies of E. coli appear dry, donut shaped and dark pink in color and are surrounded with dark pink area of precipitated bile salts.