Lauryl Tryptose Broth
Also known as：LST · Lauryl sulfate broth H · Lauryl Sulfate Broth · Lauryl Sulphate Tryptose Broth · LST Broth · LSB
For the presumptive detection of coliform organisms in water, food, and dairy products by the multiple-tube fermentation technique.
- Category
- Dehydrated Culture Media
- Dissolve per litre
- 35.6 g
- Pack sizes
- 500 g · 5 kg · 25 kg
- Certifications
- Halal
- Standard methods
- ISO 4831·APHA Standard Methods
Data updated：2026-11-07
Brand cross-reference：BD Difco Lauryl Tryptose Broth · Oxoid Lauryl Tryptose Broth · Merck Lauryl Sulfate Broth（ISO 4831、APHA Standard Methods） Brand cross-reference
Overview
Lauryl Tryptose Broth (LTB) is the standard presumptive broth in the MPN method for coliforms in water and food. Sodium lauryl sulfate suppresses non-coliforms and lactose lets coliforms produce acid and gas, observed in Durham tubes. Used for coliform testing of drinking water, food and dairy products, usually paired with EC Broth for the presumptive and confirmation steps.
Principle
Lauryl Tryptose Broth was introduced by Mallmann and Darby for the presumptive detection of coliforms.¹ Tryptose supplies nitrogen, amino acids, and growth factors, and lactose serves as the fermentable carbohydrate. The phosphate buffer maintains the pH, and sodium chloride the osmotic equilibrium. Sodium lauryl sulphate inhibits Gram-positive and many non-coliform organisms while permitting the growth of coliforms. Coliforms ferment lactose with the production of acid and gas. Gas in the Durham tube within 48 hours constitutes a positive presumptive test; positive tubes are subcultured to Brilliant Green Bile Broth 2% for confirmation of coliforms and to EC Broth for fecal coliforms.²
How selective media fit into the testing workflow
Pathogen testing normally runs in three stages: a pre-enrichment medium such as Buffered Peptone Water repairs injured cells and raises numbers, a selective enrichment then suppresses competing flora, and finally a selective differential agar isolates the target colonies. Selective agents are typically bile salts, dyes, or antibiotics; differential agents make target colonies develop a characteristic colour or morphology. Choose the combination specified by the method you follow.
Directions
Suspend 35.6 g of powder in 1 L of purified water. For the examination of 10 mL sample volumes, prepare the medium at double strength. Heat with continuous stirring and bring to the boil for 1 minute. Dispense into tubes containing inverted Durham tubes. Sterilize by autoclaving at 121°C for 15 minutes. Test the finished medium for performance using stable, standard control cultures.
Cultural response
| Test organism | ATCC | Growth |
|---|---|---|
| Escherichia coli | 25922 | good-luxuriant |
| Klebsiella aerogenes | 13048 | good-luxuriant |
| Enterococcus faecalis | 29212 | inhibited |
| Staphylococcus aureus | 25923 | inhibited |
Product highlights
- Halal certified, suitable for the Malaysian, Indonesian, and Middle Eastern markets
- Manufactured to the standard formulation, 35.6 g per litre
- Performance verified against standard control strains before release (Escherichia coli, Klebsiella aerogenes, Enterococcus faecalis, Staphylococcus aureus)
- Available in 500 g / 5 kg / 25 kg, from laboratory to industrial scale
- COA, specification sheet, and technical data sheet available; samples on request
- Manufactured in Taiwan with reliable supply
FDA BAM methods
This product corresponds to a medium used in the chapters of the US FDA Bacteriological Analytical Manual (BAM), the reference methods for FDA regulatory testing. Follow the current online edition of each chapter.
- FDA BAM Chapter 4: Enumeration of Escherichia coli and the Coliform BacteriaBAM Chapter 4EnrichmentNamed in the method as：Lauryl tryptose (LST) broth
BAM specifies methods and media formulations; it does not certify brands. Add supplements as the chapter requires, and verify media against reference strains under your quality system.
Frequently asked questions
01Does this medium meet FDA BAM methods?
BAM specifies methods and formulations, not brands. This product corresponds to a medium used in: FDA BAM Chapter 4: Enumeration of Escherichia coli and the Coliform Bacteria（BAM Chapter 4）: Enrichment. It is manufactured to the standard formulation and ships with a COA per batch; add supplements as the chapter requires and follow the current online edition.
02Can selective media be autoclaved?
Not always. Some media containing dyes or selective inhibitors lose their selectivity if overheated and should only be heated until fully dissolved, without autoclaving. Follow the preparation instructions for this product, and contact us if you are unsure.
03How much powder per litre?
Use 35.6 g per litre of deionised water; preparation and sterilisation conditions are given on the specification sheet.
04Which organisms is it suitable for?
Coliforms, Gram-negative, E. coli, Escherichia coli, Klebsiella aerogenes, Enterococcus faecalis, Staphylococcus aureus. See the cultural response table and the specification sheet.
05What are the equivalent brand products and standard methods?
Cross-reference: BD Difco Lauryl Tryptose Broth, Oxoid Lauryl Tryptose Broth, Merck Lauryl Sulfate Broth. Standard methods: ISO 4831, APHA Standard Methods. Formulations may differ slightly between makers; refer to the specification sheet.
06How is this product prepared?
Suspend 35.6 g of powder in 1 L of purified water. For the examination of 10 mL sample volumes, prepare the medium at double strength. Heat with continuous stirring and bring to the boil for 1 minute. Dispense into tubes containing inverted Durham tubes. Sterilize by autoclaving at 121°C for 15 minutes. Test the finished medium for performance using stable, standard control cultures.
07Is there a non-Halal version?
Yes. This is the Halal certified version; an equivalent standard version is also available.
08How do I request a bulk quotation, and can you provide a COA?
Yes. This product is available in 500 g, 5 kg, 25 kg. Tell us your application and volume when requesting a quotation; we reply within one working day and can supply the COA, specification sheet, and technical data sheet.
Used in these applications
Further reading
- FDA BAM Culture Media Cross-Reference: Which Media Each BAM Chapter Uses and the STBIO EquivalentAerobic plate count, coliforms and E. coli, Salmonella, Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, Vibrio, Clostridium perfringens, yeasts and moulds and Cronobacter: the media named in each FDA Bacteriological Analytical Manual chapter, matched to Taiwan-made dehydrated media for US laboratories qualifying a second source.
- Which Culture Media Do Taiwan FDA Food Microbiology Methods Specify? Cross-Reference for 21 Announced MethodsAerobic plate count, coliforms, E. coli, Enterobacteriaceae, Salmonella, Staphylococcus aureus, Listeria monocytogenes, lactic acid bacteria, yeasts and moulds, Bacillus cereus, Vibrio parahaemolyticus, Clostridium perfringens and Cronobacter: the media named in each Taiwan FDA (TFDA) announced method, matched to Taiwan-made products.
- Tryptose vs Tryptone: One Letter Apart, Different JobsTryptose is an enzymatic digest of mixed casein and meat protein used in media for fastidious organisms such as Brucella and Listeria. Tryptone is a pancreatic digest of casein alone, used in LB and TSB. Raw material, hydrolysis, specification and the formulations that call for each.
References
- 1. Mallmann W. L. and Darby C. W., 1941. Uses of a lauryl sulphate tryptose broth for the detection of coliform organisms. Am. J. Public Health, 31:127-134.
- 2. American Public Health Association, Standard Methods for the Examination of Water and Wastewater, current edition, APHA Press, Washington, D.C.