Mac Conkey Broth

• Selective enrichment medium.
• Selective Gram negative E.Coli

Comoposition                                                           Grams/liter

Pancratic digesit of gelatin -----------------------------20.000

Lactose monohydrate--------------------------------------10.000

Dehydrate Oxi Bile-------------------------------------------5.000

Bromo Cresol Purple (BCP) dye--------------------------0.01

pH = 7.3 ± 0.2 at 25⁰C

• Pancratic digist of gelatin  -----produce a nutrient
• Lactose  monohydrate--------------------------fermantable carbohydrate 
• Lactose fermenting organisms turn the medium yellow due to the acidity produced on lactose fermentation.
• Dehydroxy oxi bile ------------------inhibit the gram possitive organisum
• BCP (Bromo cresol purple) dye ----------- is the pH indicator  in the medium which turn to yellow  under acidic condition.

BCP:

• Bromo Cresol purple Dye
• Prepared as a 0.04% aqueous solution.
• Primary function indicator.
• It is used to measure albumin.
• pH above 6.8  -purple colour ………….. 
• pH below 5.2  -yellow colour …………..