Final pH 7. Media should not be used if there are any signs of deterioration shrinking, cracking, or discoloration , contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing. Consult listed references for information concerning inoculation procedures. Alternatively, a covered, boiling waterbath degrees C.
|Published (Last):||28 July 2006|
|PDF File Size:||20.64 Mb|
|ePub File Size:||14.94 Mb|
|Price:||Free* [*Free Regsitration Required]|
Crystal violet and bile salts inhibit growth primarily of the Gram-positive accompanying bacterial flora. Degradation of lactose to acid is indicated by the pH indicator neutral red, which changes its color to red, and by precipitation of bile acids.
Thus, the growth of many unwanted organisms is suppressed, while tentative identification of sought bacteria can be made. Organisms that rapidly attack lactose produce purple colonies surrounded by purple haloes. Non-fermenters or late lactose fermenters produce pale colonies with greenish zones. Red, surrounded by reddish precipitation zones, diameter mm : Lactose-positive Enterobacteriaceae: coliform bacteria, E. Pink pin-point colonies: Enterococci, possibly Klebsiella.
Colorless: Lactose-negative Enterobacteriaceae Peptic digest of animal tissue and yeast extract serve as sources of carbon, nitrogen, vitamins and other essential growth nutrients. Lactose is the fermentable carbohydrate, utilization of which leads to the production of acids.
Neutral red indicator detects the acidity so formed. Crystal violet and bile salts mixture help to inhibit the accompanying gram-positive and unrelated flora. Sodium chloride maintains the osmotic equilibrium. Heat with stirring to boiling to dissolve the medium completely. Transfer a 1 mL aliquot of the test sample to a petri dish.
Examine for purple-red colonies, 0.
Violet Red Bile Agar (VRBA)
VIOLET RED BILE (VRB) AGAR