EC with MUG Fluorogenic Agar

Water pollution caused by faecal contamination is a serious problem due to the potential for contracting diseases from pathogens (disease-causing organisms).

This medium improves the detection methods of the coliform group, in particular of E. coli, and is used to investigate drinking water, wastewater treatment systems and generally for water-quality monitoring, as well as shellfish and other foods. The medium can be used at 35 ± 2 °C for detection of coliform organisms or at 44.5 °C for isolation of E. coli.

The bile salts act as selective agent inhibiting Gram-positive bacteria, bacilli and enterococci but allowing E. coli to develop. The potassium salts have a high buffering capacity. Tryptose provides the nutrients for growth and lactose is the fermentable carbohydrate as carbon and energy source. Sodium chloride maintains the osmotic balance. Bacteriological agar is the solidifying agent.

E. coli produces the enzyme beta-D-glucuronidase that hydrolyzes MUG to yield a fluorogenic product that is detectable under long-wave (366 nm) UV light.

Preparation

Suspend 50 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Sterilize in autoclave at 121 °C for 15 minutes.

Instructions for use

1. Filtration of a test portion of the sample through a membrane filter which retains the organisms, and placement of the membrane filter on an EC with MUG Fluorogenic Agar plate.
2. Incubation at 37 ± 2 °C for 24-48 hours.

• APHA (1985) Standard Methods for Examination of Water and Wastewater, 16th Ed., pp 878-882.
• APHA (1985) Compendium of Methods for the Microbiological Examination of Foods, 2nd Ed.
• ISO 7251 Microbiology - General Guidance for enumeration of presumptive E. coli - Most Probable Number Technique. 2nd Ed. 1993-12-15.