Coliforms and E. coli · Membrane filtration
Membrane Lauryl Sulphate Broth – coliforms in water by membrane filtration
Membrane Lauryl Sulphate Broth (MLSB) is used for the enumeration of coliforms and E. coli in water by membrane filtration. Membranes are placed on absorbent pads soaked with the broth, and yellow colonies indicate lactose fermentation.
- For membrane filtration of water
- Yellow colonies = lactose fermenters
- Coliforms at 37 °C, E. coli at 44 °C
How Membrane Lauryl Sulphate Broth works
Lactose fermentation produces acid, and phenol red turns yellow under the colony. Sodium lauryl sulphate inhibits Gram-positive bacteria. Incubation at two temperatures separates total coliforms and thermotolerant coliforms.
Applications and practical notes
Membrane filtration and presence-absence media are used for coliforms and E. coli in drinking water, source water and bottled water. Typical applications include:
- Drinking water and source water monitoring
- Bottled water and ice testing
- Swimming pool and process water checks
- Laboratories working with membrane filtration
Working with Membrane Lauryl Sulphate Broth: Saturate the pads evenly without leaving free liquid, and place the membrane without trapping air bubbles.
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 the Salmonella culture method: the reference method for Salmonella in the food chain, ISO 6579-1, has four steps: non-selective pre-enrichment, selective enrichment in two broths, plating on two selective agars and confirmation of typical colonies. The FDA BAM Chapter 5 follows the same principle with media adapted to different food types. Rapid tests and identification kits shorten the time to result, but positive screening results are usually confirmed by the culture method. COLO.Science offers products for every step, so that one supplier covers the whole procedure.
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.
Membrane Lauryl Sulphate 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 Membrane Lauryl Sulphate Broth, please send us a request. With every delivery of Membrane Lauryl Sulphate Broth you receive the lot number and expiry date, and on request we send the available documentation for Membrane Lauryl Sulphate Broth.
Where Membrane Lauryl Sulphate 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 |
|---|---|---|
| Membrane Lauryl Sulphate Broth (MLSB) | PRO7517 | 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
Polje ob Sotli 4, SI-3255, Slovenia
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.
