Brilliant Green Bile Broth 2% (BGBB), also known as BRILA Broth, is a selective liquid medium widely used for confirmatory detection of coliform bacteria in water, wastewater, food, milk, and dairy products. It is commonly used after presumptive tests such as Lauryl Sulfate / Lauryl Tryptose Broth or related screening media. :contentReference[oaicite:1]{index=1}

The formulation combines 2% bile with brilliant green to inhibit Gram-positive organisms and suppress much of the accompanying flora, while lactose serves as the fermentable carbohydrate. Gas production in an inverted Durham tube is the key confirmatory reaction for coliform detection. :contentReference[oaicite:2]{index=2}

This medium is referenced in international microbiology workflows including ISO 4831 and APHA-based use patterns, and is widely represented in supplier technical documentation for food, dairy, and water microbiology applications. :contentReference[oaicite:3]{index=3}

Brilliant Green Bile Broth 2% functions as a confirmatory medium for coliform bacteria by combining selective inhibition with carbohydrate fermentation. Bile and brilliant green suppress many non-target organisms, while lactose is metabolized by coliforms with acid and gas production. Gas accumulation in the Durham tube after incubation is interpreted as positive evidence of coliform activity under the method conditions used. :contentReference[oaicite:4]{index=4}