Simmons Citrate Agar Slant 10mL , 10/Pk

Simmons Citrate Agar is a differential medium used to test an organism's ability to utilize citrate as its sole source of carbon. Provided as a 10mL slant, this tube is a cornerstone of the IMViC test series (Indole, Methyl Red, Voges-Proskauer, Citrate) used to differentiate Enterobacteriaceae.

The Biochemical Test (The "Blue" Shift): This test relies on a specific metabolic capability:

1. Selective Nutrient: The medium contains Sodium Citrate as the only carbon source and Ammonium Phosphate as the only nitrogen source. Bacteria that cannot transport citrate (citrate-negative) will not grow, and the tube will remain green.

2. The Reaction: Citrate-positive organisms (like Klebsiella pneumoniae or Enterobacter aerogenes) break down the citrate. This metabolic process produces alkaline by-products (ammonia and ammonium hydroxide).

3. The Indicator: The medium contains Bromothymol Blue, a pH indicator. As the pH rises above 7.6 due to the alkaline by-products, the medium changes color from green (neutral) to intense blue (alkaline).

The "Slant" Format:

• Aerobic Requirement: Citrate utilization is an aerobic process. The slanted surface maximizes the surface area exposed to oxygen, which is essential for the reaction to occur efficiently.

• Inoculation: The slant is inoculated by lightly streaking the surface with a pure culture.

Common Applications:

• Enteric Identification: Critical for distinguishing between coliforms. For example, E. coli is typically Citrate negative (remains green), while Enterobacter and Klebsiella are Citrate positive (turns blue).

• Water Quality: Part of the confirmation steps for coliform bacteria in water testing.

• Diagnostic Standard: Essential component of the IMViC identification suite.

• Clear Readout: Distinct color change from forest green to deep blue.

• Selective: Only citrate-permease positive organisms can grow.

• Maximized Surface: Slant format supports necessary aerobic metabolism.

• Format: Sterile 10mL agar slants in screw-cap tubes (10-pack).

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