(AB) Simmons Citrate Agar, 2 Kilograms

Koserl developed a fluid medium to determine citrate utilization. Simmon further modified the formula by adding 1.5% agar and bromthymol blue as an indicator. The medium can be used to distinguish between Escherichia coli and Enterobacter aerogenes and to assist in differentiating members of the Salmonella group. Organisms able to utilize the citrate grow well on the surface of the medium and alkalinize the medium changing it from green to blue. If the organism cannot utilize the citrate, poor or no growth is shown and medium remains unchanged. Simmons Citrate Agar is an agar medium used as a differential medium for the identification of enteric bacteria, using citrate as the sole source of carbon. (Alpha Biosciences # S19-111-2Kg)

Use: Simmons Citrate Agar is an agar medium used as a differential medium for the identification of enteric bacteria, using citrate as the sole source of carbon.

Description: Koserl developed a fluid medium to determine citrate utilization. Simmon further modified the formula by adding 1.5% agar and bromthymol blue as an indicator. The medium can be used to distinguish between Escherichia coli and Enterobacter aerogenes and to assist in differentiating members of the Salmonella group. Organisms able to utilize the citrate grow well on the surface of the medium and alkalinize the medium changing it from green to blue. If the organism cannot utilize the citrate, poor or no growth is shown and medium remains unchanged.

Formula* per Liter:

• Ammonium Dihydrogen Phosphate ..... 1.0g
• Sodium Chloride ................... 5.0g
• Dipotassium Phosphate ....................... 1.0g
• Sodium Citrate ...................... 2.0g
• Magnesium Sulfate ................................ 0.2g
• Bromthymol Blue ................. 0.08g
• Agar ......................................................15.0g

Final pH: 7.0 ± 0.2 at 25.0°C

* Grams per liter may be adj. or formula supplemented to obtain desired performance

Preparation: Mix 24.2 grams of the medium in one Liter of purified water until evenly dispersed. Heat while stirring, if necessary, to obtain solution. Distribute into test tubes and autoclave at 121.0°C for 15 minutes. After autoclaving, slant tubes to prepare deep butts.

Quality Control Specifications:

1. The powder is homogeneous, free flowing and light beige with a green tinge.
2. Visually the prepared medium is clear to trace hazy and forrest green.
3. Expected cultural response after 18-48 hours at 35.0°C.

Organism                                                            Growth                         Color

Enterobacter aerogenes ATCC 13048                 Growth                          Blue

Escherichia coli ATCC 25922                             Inhibited                        Green

Salmonella choleraesuis ATCC 13076                Growth                           Blue

Salmonella typhimurium ATCC 14028                 Growth                           Blue

Shigella dysenteriae ATCC 13313                      Inhibited                        Green

Storage: Store the sealed bottle containing the dehydrated medium at 2 to 30.0°C. Once opened and recapped, place the container in a low humidity environment at the same storage temperature. Protect it from moisture and light. The dehydrated medium should be discarded if it is not free flowing or if the color has changed from the original light beige color.