Coliforms and E. coli · Faecal coliforms at 44.5 °C
EC Broth – faecal coliforms and E. coli at elevated temperature
EC Broth is used to confirm faecal (thermotolerant) coliforms and E. coli in the MPN method. Positive presumptive tubes are subcultured into EC Broth and incubated at 44.5 °C in a water bath.
- Confirmation at 44.5 °C
- Gas = faecal coliforms
- Next step for E. coli: isolation on EMB or TBX
How EC Broth works
Bile salts inhibit Gram-positive bacteria, lactose with gas production shows fermentation, and the elevated temperature separates thermotolerant coliforms from environmental coliforms. Gas-positive tubes are streaked on selective agar for E. coli identification.
Typical reactions
| Organism | Reaction |
| Faecal coliforms / E. coli | Turbidity and gas |
| Non-thermotolerant coliforms | No gas at 44.5 °C |
Technical data
| Preparation | 37 g/L; boil to dissolve, dispense into tubes with Durham tubes, autoclave 121 °C 15 min |
| Final pH | 6.9 ± 0.2 |
| Incubation | 44.5 ± 0.2 °C, 48 h |
| Storage | Dry, dark place; keep the container tightly closed |
| Shelf life | 3 years unopened |
Applications and practical notes
In the multiple-tube (MPN) method for coliforms and E. coli, as described in FDA BAM Chapter 4 and ISO 4831, a presumptive broth is followed by confirmation broths. Typical applications include:
- Coliform and E. coli MPN counts in food and feed
- Testing of water, ice and beverages
- Hygiene monitoring in dairy, meat and ready-to-eat production
- Verification of media and methods with reference strains
Working with EC Broth: Use a circulating water bath that holds 44.5 °C accurately, because a few tenths of a degree change the result.
Good practice with dehydrated media: keep the bottle tightly closed in a cool, dry place, weigh the powder quickly to avoid moisture uptake, and use fresh distilled or deionised water. Check the pH of each new batch after preparation and before use, and label prepared media with the date. Performance of each lot can be verified with reference strains according to ISO 11133, the standard for the preparation, production, storage and performance testing of culture media.
About coliform and E. coli methods: coliforms and E. coli are counted either by the multiple-tube (MPN) method, with a presumptive broth followed by confirmation broths, or by colony counts on selective agars. FDA BAM Chapter 4 describes both approaches for food and water, and ISO 16649-2 gives the colony-count method for β-glucuronidase-positive E. coli on TBX Agar. E. coli O157 and other STEC need dedicated media, serology and PCR. COLO.Science offers media, supplements, rapid tests, identification kits and QC strains for every step.
Complete sets from one supplier: COLO.Science supplies culture media, supplements, rapid tests, identification kits and QC strains as complete sets for the method you follow. Send us your sample types and standards, and we will prepare an offer with the matching products and documentation.
EC Broth is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include EC Broth, please send us a request. With every delivery of EC Broth you receive the lot number and expiry date, and on request we send the available documentation for EC Broth.
Where EC Broth fits in coliform and E. coli testing
- Presumptive test – Lauryl Sulfate Tryptose Broth (MPN) or VRBL / chromogenic agar (colony count)
- Confirmation – BGLB Broth for coliforms; EC or EC-MUG Broth at 44.5 °C for E. coli
- Isolation – EMB, MacConkey, TBX or chromogenic E. coli agar
- Identification – IMViC kit; for O157 and STEC: SMAC or chromogenic O157 agar, latex and PCR
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| EC Broth | PRO7431 | 500 g |
Product notice: preparation, storage conditions and shelf life are given on the label. Technical data on this page are for orientation; the label and the lot documentation apply. B2B prices are quoted net, excluding VAT.
Sales and technical support
COLO LabExperts
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Quotations and technical support for culture media and microbiology products across our international sales territory. B2B prices are net, excluding VAT.
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Need the complete set for your method?
Send the sample type, target organism and the standard you follow. COLO.Science will put together the media, supplements, QC strains and confirmation tests for the whole procedure.
