Eosin Methylene Blue Agar is a solid medium used for the detection of Enterobacteriaceae. Pancreate Digest of Gelatin provides essential nutrients for bacterial growth. Sucrose and Lactose are the fermentable carbohydrates. Dipotassium Phosphate is the pH buffer. Agar is the gelifying agent. The dyes Eosin Y and Methylene Blue are toxic to most Gram-positive bacteria and serve as pH indicators. Rapid Lactose- or Sucrose-fermenting microorganisms produce sufficient quantities of acid to shift the color of the pH indicators to dark purple. E. coli produces a characteristic green metallic sheen. Non-fecal coliforms cannot ferment these carbohydrates and form normally-colored or colorless colonies on this medium.