Simmons Citrate Agar, 2.5 kg

These media are used for the differentiation between Enterobacteriaceae and the members of aerogenes group on the basis of citrate utilization as sole carbon source. Initially the citrate medium was developed by Koser (1) containing ammonium salt as the only nitrogen source and citrate as the only carbon source for differentiating Escherichia coli and Enterobacter aerogenes by IMViC tests. Later on Simmons (2) modified Kosers formulation by adding agar and bromothymol blue (3). It is recommended by APHA (4).It is also recommended by BIS (5) for isolation of Escherichia coli . Ammonium dihydrogen phosphate and sodium citrate serves as the sole nitrogen and carbon source respectively. Bromo thymol blue is the pH indicator. The organisms produce an alkaline reaction which is indicated by the change in colour from green to blue. Storage and Shelf-life: Store below 30°C in tightly closed container the prepared medium at 2 - 8°C. Use before expiry date on the label. References: 1. Koser, 1923, J. Bact., 8:493. 2. Simmons, 1926, J. Infect. Dis., 39:209. 3. MacFaddin J., 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. 1, Williams and Wilkins, Baltimore. 4. American Public Health Association, 1981, Standard Methods for the Examination of Water and Wastewater, 15th ed., APHA Inc., Washington,D.C. 5. Bureau of Indian Standards, IS:5887 (Part II) 1976, reaffirmed 1986