What is a selective differential medium?
Selective and differential media are used to isolate or identify particular organisms. Selective media allow certain types of organisms to grow, and inhibit the growth of other organisms.
What is a selective medium?
Selective media are used to select for the growth of a particular “selected” microorganism. For example, if a certain microbe is resistant to aparticular antibiotic (e.g., novobiocin), then that antibiotic can be added to the medium in order to prevent other organisms, which are not resistant, from growing.
What is a selective differential agar?
Selective and differential media are two types of growth media used to isolate and identify microorganisms. Selective media are used to isolate a particular type of microorganism by giving a specific condition for the growth of that particular microorganism.
What is a differential medium?
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 are the examples of selective media?
Examples of selective media:
- Eosin methylene blue contains dyes that are toxic for Gram-positive bacteria.
- YM (yeast extract agar) has a low pH, deterring bacterial growth.
- MEA (malt extract agar) has a low pH, deterring bacterial growth.
- MacConkey agar is for Gram-negative bacteria.
What is non selective medium?
Non-selective media are intended to cultivate microorganisms in order to multiply them. It is a simple culture medium without a selection agent that will allow the growth of microorganisms in an undifferentiated way.
What is non-selective medium?
What type of media is TSA?
EXAMPLES OF MEDIA USED IN THE LAB: 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.
Why MacConkey agar is selective and differential?
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.
What does TSA contain?
TSA contains enzymatic digests of casein and soybean meal, which provide amino acids and other nitrogenous substances, making it a nutritious medium for a variety of organisms. Glucose is the energy source. Sodium chloride maintains the osmotic equilibrium, while dipotassium phosphate acts as buffer to maintain pH.
What are the different types of selective media?
What type of media is MacConkey agar?
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.
What is an example of a differential media?
MacConkey’s Agar (MAC) At the same time, it is a differential medium that allows for the differentiation of organisms that can ferment lactose from those that cannot. MacConkey’s Agar is recommended for use in the detection and isolation of all types of dysentery, typhoid, and paratyphoid bacteria (Salmonella).
What is TSA medium?
TSA is the medium specified as Soybean-Casein-Digest Agar Medium by the United States Pharmacopeia (USP) for the total aerobic count portion of microbial limit testing procedures. The medium is also used for maintenance of stock cultures, plate counts and isolation of organisms from a variety of specimen types.
What are TSA plates?
Ready to use Tryptic (Trypticase) Soy Agar (TSA) plates for the growth of nonfastidious and moderately fastidious microorganisms. The combination of soy and casein peptones supply organic nitrogen in the form of amino acids and polypeptides, making the medium highly nutritious.
Why is MacConkey agar selective and differential?
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.
How is MacConkey agar both selective and differential?
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.
Is blood agar a differential and or a selective medium?
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.