Fraser Broth Base
Also known as：Fraser · Fraser Broth · Fraser Listeria Enrichment Broth Base · Half Fraser Broth Base
For the selective enrichment of Listeria species from food and environmental samples, following the addition of Fraser Broth Supplement.
- Category
- Dehydrated Culture Media
- Dissolve per litre
- 54.95 g
- Pack sizes
- 500 g · 5 kg · 25 kg
- Certifications
- ISO 22000
Data updated：2026-11-06
Overview
Fraser Broth Base is the secondary enrichment broth specified by ISO 11290-1 for Listeria: lithium chloride and the nalidixic acid and acriflavine added before use suppress competing flora, while aesculin and ferric ammonium citrate turn the broth black when Listeria hydrolyse aesculin, an early indicator of a positive enrichment; the same base with half-strength supplement is Half Fraser for the primary enrichment. Laboratories working to ISO methods or export verification pair it with ALOA and PALCAM plates. The Taiwan FDA announced method uses BLEB instead, so the two schemes differ. A base formulation; add supplements per the method.
Principle
Fraser Broth is a modification of UVM Listeria Enrichment Broth developed by Fraser and Sperber for the detection of Listeria species through esculin hydrolysis.¹ Peptone, tryptone, beef extract, and yeast extract supply nitrogen, amino acids, vitamins, and growth factors. The high sodium chloride content and the phosphate buffer system support the growth of Listeria while maintaining the pH during incubation. Lithium chloride inhibits enterococci, nalidixic acid inhibits Gram-negative bacteria, and acriflavine suppresses other Gram-positive organisms. Listeria species hydrolyse esculin to esculetin, which reacts with ferric ions from the supplement to form a black complex, so that blackening of the broth indicates the presumptive presence of Listeria. In ISO 11290-1, Half Fraser Broth is used for primary enrichment and full-strength Fraser Broth for secondary enrichment, followed by subculture onto selective agar.²
Directions
Suspend 54.95 g of powder in 1 L of purified water. Heat with continuous stirring and bring to the boil for 1 minute. Sterilize by autoclaving at 121°C for 15 minutes. Cool below 50°C and aseptically add Fraser Broth Supplement to give final concentrations of 0.5 g/L ferric ammonium citrate, 20 mg/L nalidixic acid, and 25 mg/L acriflavine hydrochloride; for Half Fraser Broth, add the selective agents at half concentration. Mix well and dispense into sterile tubes. Test the finished medium for performance using stable, standard control cultures.
Cultural response
| Test organism | ATCC | Growth |
|---|---|---|
| Listeria monocytogenes | 19111 | good-luxuriant |
| Listeria monocytogenes | 13932 | good-luxuriant |
| Enterococcus faecalis | 29212 | inhibited |
| Escherichia coli | 25922 | inhibited |
Product highlights
- Food-grade raw materials, produced in an ISO 22000 certified facility
- Manufactured to the standard formulation, 54.95 g per litre
- Performance verified against standard control strains before release (Listeria monocytogenes, Listeria monocytogenes, Enterococcus faecalis, Escherichia coli)
- 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
Food grade versus laboratory grade
Most culture media suppliers use laboratory-grade raw materials, which are held to lower standards for heavy metal residues, microbial contamination control, and traceability. That is adequate for pure research but not for applications with stricter raw-material requirements. STBIO manufactures with food-grade raw materials throughout, in a facility certified to ISO 22000 food safety management.
- Food microbiology laboratories working to ISO 17025 or equivalent requirements
- Biotech manufacturers exporting fermentation products and needing full raw-material traceability
- Organisations with ESG or compliance audit requirements across their supply chain
- Companies sourcing both Halal and non-Halal products who need one consistent material grade
Frequently asked questions
01How much powder per litre?
Use 54.95 g per litre of deionised water; preparation and sterilisation conditions are given on the specification sheet.
02Which organisms is it suitable for?
Pathogens, Gram-positive, Listeria, Listeria monocytogenes, Enterococcus faecalis, Escherichia coli. See the cultural response table and the specification sheet.
03Can it be used for food-grade applications?
Yes. It is made from food-grade raw materials in an ISO 22000 certified facility and is suitable for culturing starters for fermented products that are consumed directly.
04How is this product prepared?
Suspend 54.95 g of powder in 1 L of purified water. Heat with continuous stirring and bring to the boil for 1 minute. Sterilize by autoclaving at 121°C for 15 minutes. Cool below 50°C and aseptically add Fraser Broth Supplement to give final concentrations of 0.5 g/L ferric ammonium citrate, 20 mg/L nalidixic acid, and 25 mg/L acriflavine hydrochloride; for Half Fraser Broth, add the selective agents at half concentration. Mix well and dispense into sterile tubes. Test the finished medium for performance using stable, standard control cultures.
05How 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.
Further reading
References
- 1. Fraser J. A. and Sperber W. H., 1988. Rapid detection of Listeria spp. in food and environmental samples by esculin hydrolysis. J. Food Prot., 51:762-765.
- 2. ISO 11290-1, Microbiology of the food chain — Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. — Part 1: Detection method, International Organization for Standardization, Geneva.