Proteose peptone and yeast extract provide nitrogenous compounds, vitamin B complex and other essential growth nutrients.Bile, a derivative of bile salts and sodium citrate inhibit gram-positive bacteria and coliforms (5). Sodium thiosulphate servesas a good source of sulphur, which in combination with ferric citrate detects the production of hydrogen sulphide. For themetabolism of Vibrio's, sucrose is added as a fermentable carbohydrate. Vibrio that is able to utilize sucrose will from yellowcolonies. Bromothymol blue and thymol blue are the pH indicators. The alkaline pH of the medium improves the recovery ofV.cholerae. Strains of V. cholerae produce yellow colonies on TCBS Agar because of fermentation of sucrose.V. alginolyticus also produce yellow colonies. V.parahaemolyticus is a sucrose non-fermenting organism and thereforeproduces blue-green colonies, as does V.vulnificus.