EC Medium was designed to improve the isolation and detection of E coli in contaminated water, milk and shellfish. APHA recommends that EC Medium be used for the determination of water pollution. The addition of 4-methylumbelliferyl-B-D-glucuronide (MUG) to EC Medium allows for the rapid detection (4-24 hours) of E coli when the incubated medium is observed for fluorescence using a long-wave UV light (365 nm) source. It can also detect anaerogenic E. coli strains. Most strains of E. coli produce B-glucuronidase which hydrolyzes MUG to the fluorogenic compound 4-methyl-umbelliferone. Studies by Feng and Hartman noted that most E. coli strains (96%) and all enterotoxigenic E. coli strains (100%) and a moderate number of Salmonella (17%) and Shigella (40%) stains produce B-glucuronidase. False positives can also be caused by Streptococcus sp. To eliminate false positive results with oyster samples an enrichment step in Lauryl Sulfate Broth is recommended and then subsequent transfer to EC Medium with MUG. Selective broth medium used to detect the presence of Escherichia coli in water and food samples by a fluorogenic procedure. (Alpha Biosciences # E05-101-500gm)
Use: Selective broth medium used to detect the presence of Escherichia coli in water and food samples by a fluorogenic procedure.
Description: EC Medium was designed to improve the isolation and detection of E coli in contaminated water, milk and shellfish. APHA recommends that EC Medium be used for the determination of water pollution. The addition of 4-methylumbelliferyl-B-D-glucuronide (MUG) to EC Medium allows for the rapid detection (4-24 hours) of E coli when the incubated medium is observed for fluorescence using a long-wave UV light (365 nm) source. It can also detect anaerogenic E. coli strains. Most strains of E. coli produce B-glucuronidase which hydrolyzes MUG to the fluorogenic compound 4-methyl-umbelliferone. Studies by Feng and Hartman noted that most E. coli strains (96%) and all enterotoxigenic E. coli strains (100%) and a moderate number of Salmonella (17%) and Shigella (40%) stains produce B-glucuronidase. False positives can also be caused by Streptococcus sp. To eliminate false positive results with oyster samples an enrichment step in Lauryl Sulfate Broth is recommended and then subsequent transfer to EC Medium with MUG.
Formula* per Liter:
- Casein Digest of Peptone .............. 20.0g
- Lactose ................................ 5.0g
- Sodium Chloride ................................ 5.0g
- Bile Salts Mixture .................1.5g
- Monopotassium Phosphate ..............1.5g
- Disodium Phosphate ...........4.0g
- MUG .................................................. 0.05g
Final pH: 6.9 ± 0.2 at 25.0°C
* Grams per liter may be adj. or formula supplemented to obtain desired performance
Preparation: Mix 37 grams of the medium in one Liter of purified water until evenly dispersed. Heat with repeated stirring to dissolve completely. Prepare double strength broth for evaluating 10 mL samples. Distribute into test tubes containing inverted Durham tubes and autoclave at 121.0°C for 15 minutes.
Quality Control Specifications:
- The powder is homogeneous, free flowing and light beige.
- Visually the prepared broth is light to medium gold and clear.
- Expected cultural response after 18-24 hours at 44.5°C.
Organism                                                                  Result
Escherichia coli ATCC 25922Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Growth, Gas +, Fluorescence +
Enterobacter aerogenes ATCC 13048Â Â Â Â Â Inhibited, Gas -, Fluorescence -
Enterococcus faecalis ATCC 29212Â Â Â Â Â Â Â Â Â Inhibited, Gas -, Fluorescence -
Storage: Store the sealed bottle containing the dehydrated medium at 2 to 30.0°C. Once opened and recapped, place the container in a low humidity environment at the same storage temperature. Protect it from moisture and light. The dehydrated medium should be discarded if it is not free flowing or if the color has changed from the original light beige color.
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