KOSER CITRATE MEDIUM

Coliform bacteria serve as bacterial indicators of sanitary quality of food and water. These bacteria are normally found in the intestinal tract of humans and many warm-blooded animals. Coliforms encompasses mostly of Enterobacteriaceae from the genera Enterobacter, Klebsiella, Escherichia, and Citrobacter. The characteristics of the members of Enterobacteriaceae are that they are gram-negative rods and ferment glucose to form acid along with gas production. Two important members of the Enterobacteriaceae family are Escherichia coli and Enterobacter aerogenes. Both can be differentiated on the basis of IMViC test. Enterobacter species are able to utilize sodium citrate as the sole carbon source while E. coli fail to do so. This property is used to differentiate the coli-aerogenes group. Koser Citrate Medium is used as a base for studying citrate utilization tests. This medium is recommended by APHA, and others, to presumptively identify coliforms encountered in the food and dairy industry.

for di?erentiation of Escherichia coli and Enterobacter aerogenes on the basis of citrate utilization