Description

INTENDED USE

Recommended for enumeration of fecal coliform by membrane filtration technique with the addition of chromogenic supplement. It can also be used for clinical samples.

SUMMARY AND EXPLANATION

Geldreich et al. formulated a medium to enumerate fecal coliforms (MFC) using the membrane filter (MF) technique without prior enrichment. Fecal coliforms (i.e., those found in the feces of warm-blooded animals) are differentiated from coliforms from environmental sources by their ability to grow at 44.5 ± 0.5°C.

Many “standard methods” membrane filtration procedures specify m FC medium for testing water. The American Public Health Association (APHA) specifies m FC medium and incubation at 44.5 ± 0.5°C in the fecal coliform membrane filter procedure, the delayed-incubation fecal coliform procedure and the two-layer agar method for recovering injured fecal coliforms. AOAC International specifies m FC Agar for detecting total coliforms and fecal coliforms in foods.

The U. S. Environmental Protection Agency specifies using m FC medium in fecal coliform methods for testing water by the direct MF method or the delayed-incubation MF method.

PRINCIPLE

Coliform bacteria are the members of the Enterobacteriaceae and are present in large numbers in feces and sewage. The presence of coliform bacteria, which grow at 44°C, confirms serious water contamination. Membrane filter technique is the most common technique used in the detection of fecal coliforms as recommended by APHA. This medium is formulated in accordance with Ciebin et.al.. The chromogenic substrate, 5-bromo-4-chloro-3-indolyl-beta-D-glucuronide (BCIG) in the medium is cleaved by the presence of enzyme ß- glucuronidase in E.coli thereby producing blue coloured colonies.

m FC Agar contain peptones as sources of carbon, nitrogen, vitamins and minerals. Yeast extract supplies B-complex vitamins that stimulate bacterial growth. Lactose is a carbohydrate. Bile Salts No. 3 inhibits growth of gram-positive bacteria. m FC Agar contains agar as the solidifying agent.