What is the difference between selective media and common media?

What is the difference between selective media and common media?

Culture media are used to grow, isolate, differentiate and identify microorganisms. Media are included with necessary nutrients for the growth of microorganisms. Selective media allow the growth of a specific type of microorganisms and inhibit the rest of the other microorganisms.

What is a 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 are two examples of selective media?

Examples of selective media:

• Eosin methylene blue contains dyes that are toxic for Gram-positive bacteria.
• YM (yeast extract, malt extract agar) has a low pH, deterring bacterial growth.
• MacConkey agar is for Gram-negative bacteria.
• Hektoen enteric agar is selective for Gram-negative bacteria.

Is Mac differential or selective?

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.

Which of the following 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.

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.

Why is selective and differential media important?

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. Differential media are used to differentiate closely related organisms or groups of organisms.

Is Thayer Martin Agar selective or differential?

Thayer-Martin agar is a selective medium used for the isolation of gonococci (Neisseria gonorrheae) from specimens containing a mixed flora of bacteria and/or fungi e.g. urogenital specimen. Modified Thayer-Martin (MTM) agar is a GC agar base containing vancomycin, colistin, nystatin, and trimethoprim lactate (VCNT).

Is E coli fastidious?

Escherichia coli – non-fastidious, lactose fermenter. Staphylococcus epidermidis – requires pre-formed growth factors to be provided in the growth medium. Pseudomonas aeruginosa – non-fastidious.

What is an example of a selective and differential media that can be used to identify different Staphylococcus isolates?

Mannitol Salt Agar (MSA) is a selective medium for the isolation of pathogenic and non-pathogenic Staphylococci. Growth of most other organisms is inhibited by a high salt content (7.5% NaCl). MSA also acts as a differential medium for the differentiation of organisms that can ferment mannitol from those that cannot.