Thermo Scientific™ Remel™ Simmons Citrate Agar, Dehydrated

Description

• Differentiate gram-negative bacteria based on citrate utilization using Thermo Scientific™ Remel™ Simmons Citrate Agar (Dehydrated)
• In 1923, Koser developed a liquid medium to differentiate Escherichia coli and Enterobacter aerogenes 1
• The medium contained an inorganic ammonium salt and sodium citrate that provided a single nitrogen source and a single carbon source, respectively
• In 1926, this formulation was modified by Simmons who added 1.5% agar and brom thymol blue indicator 2
• Gram-negative bacteria that can utilize ammonium dihydrogen phosphate as a sole nitrogen source and sodium citrate as a sole carbon source will grow on Simmons Citrate Agar
• The organisms extract nitrogen from the ammonium salt by breaking it down to form ammonia, leading to alkalization of the medium
• This causes the brom thymol blue indicator to change color from green to blue.