Quick Answer: Can A Medium Be Both Selective And Differential?

Which media is 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..

What type of medium is TSA?

Tryptic Soy Agar (TSA): is a rich, undefined medium containing products of an enzymatic digest of protein and soy product. Organisms that require vitamins or other growth factors are able to grow on TSA.

What makes MacConkey selective and/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 differential for?

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.

Why is MacConkey agar selective as well as differential quizlet?

Why is MacConkey agar selective as well as differential? It’s selective to gram negative enteric bacteria because it contains bile salts, which inhibit most gram positive bacteria. It also contains lactose, which differentiates between gram negative lactose fermenter and gram negative non-fermenters.

Is TSA selective or differential?

TSA (Trypticase Soy Agar) and NA (Nutrient Agar) are General Purpose Media that are not selective or differential, their purpose is simply to grow many types of bacteria cheaply. Here we will use a general purpose media to compare the growth on the selective and differential media.

Which bacteria did MacConkey selective for?

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.

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 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.

Why is MacConkey gram negative?

Gram-negative enteric bacteria that grow on MacConkey agar are differentiated by their ability to ferment lactose. If the lactose is fermented by the bacteria, the production of the acid drops the pH of the media.

Is chocolate agar selective or differential?

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

Why do we use TSA plates?

Trypticase soy agar or tryptone soya agar (TSA) and Trypticase soy broth or tryptone soya broth (TSB) with agar are growth media for the culturing of bacteria. They are general-purpose, nonselective media providing enough nutrients to allow for a wide variety of microorganisms to grow.