Bile esculin agar

General: Both differential and selective agar used in plates or slants. Used to differentiate enterococci and group D streptococci. Consists of 40% bile (oxgall), which inhibits other streptococci. These microbes are able to hydrolyze esculin into esculetin and dextrose; the former complexes with ferric citrate, resulting in dark brown to black precipitate.