How is MacConkey agar media prepared?

Preparation of MacConkey Agar

  1. Suspend 49.53 grams of dehydrated medium in 1000 ml purified/distilled water.
  2. Heat to boiling to dissolve the medium completely.
  3. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes.
  4. Cool to 45-50°C.
  5. Mix well before pouring into sterile Petri plates.

What is the composition of MacConkey agar?

Contents. It contains bile salts (to inhibit most Gram-positive bacteria), crystal violet dye (which also inhibits certain Gram-positive bacteria), and neutral red dye (which turns pink if the microbes are fermenting lactose).

What is MacConkey and how is it prepared for microbial analysis?

MacConkey Agar is a solid, selective and differential agar that only cultivates gram-negative bacterial species, it can further differentiate Gram-negative organisms based on their lactose metabolism: Lactose fermenters, colonies, turn red or pink on MacConkey agar. Non-fermenters do not change color.

Why is MacConkey agar important?

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 Colour is MacConkey agar?

What is MacConkey broth made of?

MacConkey Broth is a modification of the medium developed by MacConkey which contained 0.5% sodium taurocholate and litmus as an indicator. 1 The presence of Oxgall replaces the sodium taurocholate to inhibit gram positive organisms.

What is the purpose of MacConkey agar?

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 bacteria grows on MacConkey?

◈ Differentiation : Gram-negative bacteria that grow on MacConkey plate are differentiated by their ability to ferment lactose. Colonies of Escherichia coli on MacConkey agar palte are pink to dark pink, dry and donut-shaped, surrounded by a dark pink area of precipitated bile salts.

What is a MacConkey medium?

The macconkey medium is developed by Alfred Theodore MacConkey in 1900. Ⅱ. Preparation / Composition Suspend the components, dehydrated powder, in water (49.53 grams in 1000 ml of purified / distilled water).

What is MacConkey broth media used for?

Besides being a Differential solid medium, MacConkey Broth Medium is a selective and differential medium too same as that of MacConkey Agar medium and primarily used for the isolation of Gram-negative and enteric bacilli, the rod-shaped bacteria.

Why is MacConkey agar a selective media?

Bile salt – The Bile salts present in MacConkey Agar medium (MAC) is the basis for making MAC a Selective media. It inhibits the growth of most of the Gram-Positive bacteria and the Gram-Negative remains unaffected.

How do you differentiate bacteria on a MacConkey plate?

◈ Differentiation : Gram-negative bacteria that grow on MacConkey plate are differentiated by their ability to ferment lactose. Bacteria which ferment lactose decrease the pH of the medium, this decrease is detected by neutral red (become red if pH below 6.8).