Liofilchem® C-EC MF Agar, 500g

Liofilchem® C-EC MF Agar is a chromogenic and fluorogenic selective medium used in microbiological water analysis for the quantitative detection of Escherichia coli and other coliform bacteria within 18–24 hours.

It is specifically designed for membrane filtration techniques and allows simultaneous detection, enumeration, and indole confirmation of E. coli colonies.

By combining chromogenic (X-GAL) and fluorogenic (MUG) substrates, the medium enables easy identification through distinct colony coloration and fluorescence, ensuring rapid and accurate monitoring of microbial contamination in drinking, surface, or wastewater samples.

Key Features

• Dual-detection technology: Combines chromogenic and fluorogenic substrates for rapid E. coli and coliform differentiation.
• X-GAL substrate for β-galactosidase detection in coliforms (blue-green colonies).
• MUG substrate for β-glucuronidase detection in E. coli (fluorescent colonies under 366 nm UV light).
• Enables indole test confirmation directly on the plate.
• Rapid results: 18–24 hours incubation.
• Flexible temperature range:
  • 37 ± 1 °C for total coliform detection.
  • 44 ± 0.5 °C for fecal coliforms and E. coli.
• Conforms to APAT CNR-IRSA and ISO analytical guidelines for water microbiology.

Typical Formula (per litre)

Principle of the Method

• Peptone, peptocomplex, and yeast extract provide essential nutrients and B-vitamins for microbial growth.
• Tryptophan enhances indole production for E. coli confirmation.
• Bile salts inhibit Gram-positive flora.
• X-GAL and IPTG detect β-galactosidase activity in coliforms (blue-green coloration).
• MUG detects β-glucuronidase activity typical of E. coli, producing fluorescence under UV light (366 nm).
• Agar solidifies the medium for membrane filtration assays.

Preparation

1. Suspend 40.73 g of powder in 1 L of distilled or deionized water.
2. Mix thoroughly and heat with agitation until fully dissolved.
3. Autoclave at 121 °C for 15 minutes.
4. Cool to 45–50 °C, mix well, and pour into sterile Petri dishes.

Test Procedure

1. Filter an appropriate water volume through a sterile membrane filter (0.45 µm).
2. Place the membrane on a prepared C-EC MF Agar plate.
3. Incubate 18–24 h under aerobic conditions at the chosen temperature:
   • 37 °C for total coliforms,
   • 44 °C for fecal coliforms and E. coli.
4. Examine for characteristic colonies:
   • E. coli: blue-green colonies, fluorescent under UV, indole positive.
   • Other coliforms: blue-green colonies, non-fluorescent.
   • Non-coliforms: yellow or colorless colonies (inhibited or weak growth).

Interpretation of Results

E. coli colonies fluoresce at 366 nm and turn red-purple with Kovac’s reagent confirming indole positivity.

Appearance

Storage and Stability

• Store dehydrated powder at 10–30 °C in a dry environment.
• Store ready-to-use plates at 2–8 °C, protected from light.
• Shelf life:
  • Dehydrated medium – 4 years
  • Ready-to-use plates – 4 months
• Discard if contaminated or discolored.

Quality Control

• Inoculum for productivity: 50–100 CFU
• Inoculum for selectivity: 10⁴–10⁶ CFU
• Incubation: 18–24 h at 37 ± 1 °C, aerobic

Ordering Information

Liofilchem® C-EC MF Agar provides a fast, reliable, and accurate medium for the detection and enumeration of Escherichia coli and other coliforms in all types of water samples. Its dual chromogenic–fluorogenic system allows clear visual differentiation and indole confirmation, offering laboratories an efficient solution for water quality monitoring and sanitary testing in compliance with APAT CNR-IRSA, ISO, and APHA standards.