Description
Cat# BC-44107
Recommended for the selective enrichment of E.coli from pharmaceutical products in accordance with the microbial
limit testing by harmonized methodology of USP/EP/BP/JP.
Composition**
Ingredients Gms / Litre
Gelatin peptone# 20.000
Lactose monohydrate 10.000
Dehydrated bile## 5.000
Bromo cresol purple 0.010
pH after sterilization ( at 25°C) 7.3±0.2
**Formula adjusted, standardized to suit performance parameters
Directions
Suspend 34.51 grams (the equivalent weight of dehydrated medium per litre) in 1000 ml purified/ distilled water. Heat if
necessaryto dissolve the medium completely. Dispense into test tubes with inverted Durham tubes. Sterilize by autoclaving
at 15 lbs pressure (121°C) for 15 minutes or as per validated cycle.
Principle And Interpretation
MacConkey Broth is a modification of MacConkey Medium (7). Childs and Allen (2) demonstrated the inhibitory effect of
neutral red and therefore substituted it by the less inhibitory bromocresol purple dye. BCP is more sensitive in recording pH
variation in the medium. This medium is prepared in accordance with the harmonized method of USP/BP/JP (8,1,5)
Gelatin peptone provides essential growth nutrients. Lactose is the fermentable carbohydrate. Dehydrated bile inhibits grampositive
organisms. Bromocresol purple is the pH indicator in the medium, which turns yellow under acidic condition.
Lactose fermenting organisms turn the medium yellow due to the acidity produced on lactose fermentation. The colour
change of the dye is observed when the pH of the medium falls below 6.8. Lactose non-fermenting organisms like Salmonella
and Shigella do not alter the appearance of the medium.
Transfer homogenate in Soyabean Casein Digest Medium (MH011) containing 1 gm or 1 ml of the preparation to be examined
to 100 ml MacConkey Broth Incubation is carried at 43°-45°C for 24-48 hours. For further isolation, subculture on MacConkey
Agar (MH081). Growth of red generally non-mucoid colonies, sometimes surrounded by a reddish precipitation zone, indicates
pressure of coliforms.
# Pancreatic digest of gelatin
## Equivalent to Dehydrated Ox-bile
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