Violet Red Bile Glucose Agar (ISO), 500g

Violet Red Bile Glucose Agar is used for the enumeration of Enterobacteriaceae in foods and is not intended for use in the diagnosis of disease or other conditions in humans. Formulated according to ISO 21528:2017 (all parts), VRBGA is a modification of Violet Red Bile Lactose Agar (NCM0089) introduced by Mossel in 1978. VRBA contains lactose, which is fermented by members of the coli/ aerogenes group; this medium gives a ‘coliform’ count. The VRBGA formula modification replaces lactose with glucose. Glucose is fermented by all members of the Enterobacteriaceae, thus giving a presumptive Enterobacteriaceae count. Bile salts and crystal violet are used to inhibit gram-positive and non-enteric organisms. The overlay procedure ensures anaerobic conditions and suppresses the growth of non-fermentative gram-negative bacteria.

Typical Formulation

Formula Litre
Yeast Extract 3.0 g/L
Enzymatic digest of Animal Tissue 7.0 g/L
Bile Salts 1.5 g/L
Sodium Chloride 5.0 g/L
Glucose 10.0 g/L
Agar 12.0 g/L
Neutral Red 0.03 g/L
Crystal Violet 0.002 g/L

Preparation

Suspend 38.5 grams of the medium in one litre of purified water.
Heat with frequent agitation and boil for one minute to completely dissolve the medium.
DO NOT AUTOCLAVE.
Cool to 45-50°C.