Bifidobacterium Agar Beerens, Modified 20. This agar is a partially selective medium for the isolation of bifidobacteria especially, but not only, from human stool specimens.Bifidobacterium Medium as described by Beerens is based on Columbia Agar base, supplemented with propionic acid, at pH 5.0.Propionic acid has been shown to inhibit fungi and many bacteria other than bifidobacteria. The low pH of the medium furthercontributes to inhibit other predominating organisms of human feces, such as Bacteroides and Eubacterium species. BDBifidobacterium Agar, Modified is a slight modification of the original medium, supplemented with lactulose, a sugar used as a prebiotic that is preferably fermented by bifidobacteria. Glucose as a universal sugar has been added to accelerate initial growth. Riboflavin is a vitamin for many bifidobacteria. The pH has been slightly increased from 5.0 to 5.5 to improve gel strength of the agar and better growth of Bifidobacterium.