Gelatin Salt Agar is recommended for the cultivation and differentiation of Vibrio species from food. This medium is used to screen isolates for salt tolerance including certain vibro species. High concentrations of NaCl and alkaline pH have also been used to select certain Vibrio species, based on the ability of most Vibrios to grow at pH values above 8.0 and at or higher concentrations of NaCl. An opaque halo is observed around growth of gelatinase positive organisms.