Simmons Citrate Agar - 7156
Intended Use:
Simmons Citrate Agar is specifically designed for the differentiation of microorganisms based on their ability to utilize citrate as a carbon source.
Product Summary and Explanation
Originally developed by Koser, this medium serves a pivotal role in distinguishing coliform bacteria, particularly the differentiation of typical fecal coliforms from non-fecal coliforms. Fecal coliforms are generally incapable of utilizing citrate as the sole carbon source and rely on inorganic ammonium salts for nitrogen, while non-fecal coliforms—such as Enterobacter aerogenes—can metabolize citrate, resulting in an alkaline environment. One notable challenge associated with Koser's liquid medium is its potential turbidity due to large inoculum sizes, which can obscure results even in the absence of growth. To overcome this limitation, Simmons innovated a solid medium that minimizes turbidity issues.
This formulation enhances Koser’s original medium by incorporating bromthymol blue—a pH indicator—along with a 1.5% agar content, thus providing a solid growth medium that allows for clear differentiation. Microorganisms capable of metabolizing citrate will exhibit vigorous growth, alkalizing the medium and causing a remarkable color change from green to deep blue within 24 to 48 hours. In contrast, Escherichia coli either fails to grow on this medium or grows insufficiently to produce a detectable reaction change.
Simmons Citrate Agar is especially recommended for the differentiation of enteric Gram-negative bacilli isolated from clinical specimens, aquatic environments, and food samples, serving as a crucial tool in microbiological analysis and research.
Key Features:
- Developed for specific differentiation based on citrate utilization.
- Solid medium effectively eliminates turbidity associated with liquid cultures.
- Color change indicates microbial activity, facilitating quick analysis.
- Ideal for studying enteric Gram-negative bacilli from various sources.
Specifications:
| Brand |
Product Code |
Composition |
| Acumedia |
7156 |
Modified Koser's Medium with bromthymol blue and 1.5% agar |
| BD / BBL |
211620 |
N/A |
| Oxoid |
CM0155 |
N/A |
| Merck |
1.02501 |
N/A |
