Can a media be 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.
Can media be selective and differential?
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.
Which two types of media are both selective and differential?
List and describe two types of media that are both selective and differential. MacConkey Agar – MacConkey agar is a selective and differential culture medium for bacteria designed to selectively isolate Gram-negative and enteric bacilli and differentiate them based on lactose fermentation.
Which type of media is both selective and differential click all that apply?
MacConkey agar
This 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.
Why TSA media is not designated as either selective or differential?
Certain fastidious organisms, however, will fail to grow or grow poorly on TSA because it lacks the specific nutrients required by those bacteria . Even so, TSA is not classified as selective. To be selective, a medium must contain a specific substance intentionally added to inhibit certain microbes and not others.
Why is MacConkey agar considered both a selective and a differential medium?
This 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 are selective and differential media and how do they differ?
Selective media are the culture media designed for the growth of a selected organism while inhibiting the growth of other microorganisms. Differential media are the culture media designed to distinguish microorganisms from one another by visible growth characteristics.
Is blood agar selective or differential media?
Blood agar is a differential medium that distinguishes bacterial species by their ability to break down red blood cells. The ability to break down the cells will cause a change in the color of the blood agar. Some media are both differential and selective.
Which media is considered selective and differential quizlet?
MacConkey’s Agar is both a selective and differential media; it is selective for Gram negative bacteria and can differentiate those bacteria that have the ability to ferment lactose.
Why is mannitol salt agar both selective and differential?
Mannitol Salt Agar (MSA) is both selective and differential. It contains 7.5% sodium chloride which selects for organisms that are halotolerant . It also contains the carbohydrate mannitol, and a pH indicator, phenol red, which allow distinction between organisms which can ferment mannitol and those that can not.
How can agar be both selective and differential?
Explanation for Case 2. 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 .
Is chocolate agar a differential?
Chocolate agar, a differential medium for gram-positive cocci .
Is nutrient agar a differential media?
1. Observe the growth and appearance of colonies on all plates. Notice that nutrient agar is neither a selective nor differential medium .
Is EMB agar selective or differential?
EMB agar contains peptone, lactose, sucrose, and the dyes eosin Y and methylene blue; it is commonly used as both a selective and a differential medium . EMB agar is selective for gram-negative bacteria.
Is chocolate agar plate selective or differential?
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.
Is sheep blood agar selective or differential?
Blood agar (BAP) is a differential growth medium which microbiologists use to distinguish clinically significant bacteria from throat and sputum cultures. BAP contains 5% sheep blood. Certain bacteria produce exotoxins called hemolysins, which act on the red blood cells to lyse, or break them down.
Is mannitol salt agar a differential?
This type of medium is both selective and differential . The MSA will select for organisms such as Staphylococcus species which can live in areas of high salt concentration (plate on the left in the picture below).
What is the purpose of selective and differential media lab?
Is MacConkey selective or differential?
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.
What makes a media differential?
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.
Is nutrient agar selective or differential?
Nutrient agar is a general purpose medium that supports the growth of a wide range of non-fibrous organisms.
Is MSA a differential medium or a selective medium or both or neither quizlet?
Mannitol Salt Agar (MSA) is a selective and differential medium . The high concentration of salt (7.5%) selects for members of the genus Staphylococcus, since they can tolerate high saline levels.
Is blood agar selective or differential quizlet?
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).
Would MSA medium still be selective and differential for Staphylococcus aureus if it did not have salt in it?
Would this medium still work if it did not have salt in it? Why or why not? No the high concentration of sodium makes the medium selective by inhibiting the growth of most bacteria and allowing staphylococcus aureus to grow.
Is tryptic soy agar selective or differential?
Tryptic Soy Agar (TSA): a general purpose, non-selective , non-differential, supportive medium that supports growth of all microorganisms that do not require special nutrients.
Is lactose broth selective or 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. Fermentation of this sugar results in an acidic pH and causes the pH indicator, neutral red, to turn a bright pinky-red color.
What is MacConkey agar used for?
MacConkey agar is a selective and differential culture medium for bacteria . It is designed to selectively isolate Gram-negative and enteric (normally found in the intestinal tract) bacteria and differentiate them based on lactose fermentation.
Is blood agar selective?
What is the major difference between blood agar and chocolate agar?
Chocolate agar is essentially the same as blood agar except that during preparation the red blood cells are lysed when added to molten agar base .
Is starch agar selective or differential?
Starch agar is a differential medium that tests the ability of an organism to produce certain exoenzymes, including a-amylase and oligo-1,6-glucosidase, that hydrolyze starch.
What is an example of a differential media?
Why nutrient agar is non selective?
Limitations of Nutrient agar
Because nutrient media supports the growth of many microorganisms, chances of contamination are quite high during isolation . It cannot be used as a selective medium for the cultivation of fastidious organisms that have particular nutrients requirements.
What makes EMB agar differential?
It is a selective medium due to inhibition of gram-positive bacteria by methylene blue. EMB agar’s differential property comes from the eosin and methylene blue complex formation under acidic pH . People who are working on EMB media ask the following questions frequently.
Is EMB agar selective or differential quizlet?
-Eosin Methylene Blue (EMB) agar is a complex (chemically undefined), moderately selective, and differential medium . -Eosin Methylene Blue (EMB) agar are selective for Gram-negative organisms and contain indicators to differentiate lactose fermenters from lactose non-fermenters.
Can E. coli grow on MacConkey Agar?
Streak plate of Escherichia coli and Serratia marcescens on MacConkey agar. Both microorganisms grow on this selective media because they are gram-negative non-fastidious rods .
