A medium helpful in differentiation of the Enterobacteriaceae. Simmons citrate agar test for organisms that are able to utilize citrate as a carbon source. Organisms that can utilize citrate produce an alkaline carbonate changing a pH indicator in the agar from green to blue. Some citrate negative organisms may display weak growth on the agar but will not cause a color change with the agar remaining green. 500 g Simmons Citrate Agar Use 24 grams with 1 liter of water. DOT Info: Non-regulated