MacConkey Agar without Salt & Crystal Violet

This medium was first introduced by MacConkey in 1905 for the isolation and differentiation of lactose and non-lactose fermenting enteric bacteria containing swarming strains of Proteus spp.

MacConkey agar without salt and crystal violet is a differential medium that restricts the swarming of Proteus spp. as sodium chloride is omitted from the medium to provide an electrolyte-deficient medium.

The omission of crystal violet permits the growth of Staphylococcus spp. and Enterococcus spp. The peptone is the nitrogen, carbon and vitamin source in this medium.

Lactose is a fermentable carbohydrate. Lactose fermentation causes a local pH drop around the colonies which will react with the pH indicator, neutral red, and hence aids in differentiation. Bile salts act as the selective agent.

isolation and differentiation of lactose and non-lactose fermenting enteric bacteria containing swarming strains of Proteus spp.

Shelf Life (days): 1095 days

Storage Temp (°C): 0-30°C

Dehydrated Medium Appearance: Fine Powder

Prepared Medium Appearance: Firm Gel

Dehydrated Medium Colour: Straw

Prepared Medium Colour: Pale Pink / Red

Dehydrated PH: 7.4 ± 0.2

Prepared PH: 7.4 ± 0.2

Recommended Incubation: Aerobically at 35-37°C for 18-24 hours

Formula g/L

Peptone: 20.0

Lactose: 10.0

Bile Salts: 5.0

Natural Red: 0.075

Agar: 13.0

Total: 48.0