M17 Agar Base
Also known as：M17 · M17 Agar · Terzaghi Agar · Lactic Streptococci Agar Base · M17 Medium Base
For the cultivation and enumeration of lactic streptococci, and for the enumeration of their bacteriophages by plaque assay.
- Category
- Dehydrated Culture Media
- Dissolve per litre
- 33.25 g
- pH (25 °C)
- 7.1 ± 0.5
- Pack sizes
- 500 g · 5 kg · 25 kg
- Certifications
- ISO 22000 · Halal
- Standard methods
- ISO 7889 / IDF 117
Data updated：2026-11-06
Brand cross-reference：BD Difco M17 Agar · Oxoid M17 Agar · Merck M17 Agar（ISO 7889 / IDF 117） Brand cross-reference
- Storage
- Store at 2–8 °C in sealed, dry, clean conditions.
- Shelf life
- 36 months from manufacture date when stored as directed.
Overview
M17 Agar Base is a base medium to which supplements are added per the method, intended for anaerobes and nutritionally demanding organisms. It is used to cultivate and count lactococci and Streptococcus thermophilus, often alongside MRS. STBIO manufactures it from food-grade raw materials in an ISO 22000 certified facility, with a COA for every batch. This is the Halal-certified version.
Principle
M17 Agar was developed by Terzaghi and Sandine for the isolation and enumeration of lactic streptococci from dairy products and starter cultures.¹ Peptone, soy peptone, beef extract, and yeast extract supply nitrogen, amino acids, peptides, and the B-group vitamins required by these nutritionally demanding organisms. Lactose is the fermentable carbohydrate and provides the carbon and energy source. Magnesium sulphate supplies essential cations, and ascorbic acid lowers the redox potential of the medium and stimulates growth. Agar acts as the solidifying agent. Because the medium is prepared at a low agar concentration, it is also suited to the soft-overlay technique used to enumerate bacteriophages of lactic streptococci as plaques.¹ In dairy analysis the medium is applied to the enumeration of Streptococcus thermophilus in yoghurt and other fermented milk products, where it is used alongside a selective medium for lactobacilli.²
Media for anaerobes and fastidious organisms
Anaerobes and fastidious organisms require media containing reducing agents, blood, or infusion components, together with an anaerobic incubation environment. Some formulations need heat-labile supplements such as blood, serum, or antibiotics added after sterilisation; follow the preparation instructions for the timing and method.
Specifications
| Parameter | Specification |
|---|---|
| pH (at 25°C) | 7.1 ± 0.5 |
Release specifications. Actual values are reported on the COA supplied with each batch.
Directions
Suspend 33.25 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 to 45-50°C. Mix well and pour into sterile Petri plates. Test the finished medium for performance using stable, standard control cultures.
Cultural response
| Test organism | ATCC | Growth |
|---|---|---|
| Lactobacillus delbrueckii subsp. bulgaricus | 11842 | None to poor |
| Enterococcus faecalis | 29212 | Good |
| Lactobacillus leichmannii | 4797 | Good |
| Lactiplantibacillus plantarum | 8014 | Good |
| Streptococcus thermophilus | 14485 | Good |
Product highlights
- Food-grade raw materials, produced in an ISO 22000 certified facility
- Halal certified, suitable for the Malaysian, Indonesian, and Middle Eastern markets
- Manufactured to the standard formulation, 33.25 g per litre, pH 7.1 ± 0.5
- Performance verified against standard control strains before release (Lactobacillus delbrueckii subsp. bulgaricus, Enterococcus faecalis, Lactobacillus leichmannii, Lactiplantibacillus plantarum, Streptococcus thermophilus)
- 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 33.25 g per litre of deionised water; pH after sterilisation 7.1 ± 0.5. Preparation and sterilisation conditions are given on the specification sheet.
02Which organisms is it suitable for?
Lactic acid bacteria, Gram-positive, Lactococcus, Streptococcus, Lactobacillus delbrueckii subsp. bulgaricus, Enterococcus faecalis, Lactobacillus leichmannii, Lactiplantibacillus plantarum, Streptococcus thermophilus. See the cultural response table and the specification sheet.
03What are the equivalent brand products and standard methods?
Cross-reference: BD Difco M17 Agar, Oxoid M17 Agar, Merck M17 Agar. Standard methods: ISO 7889 / IDF 117. Formulations may differ slightly between makers; refer to the specification sheet.
04Can 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.
05How is this product prepared?
Suspend 33.25 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 to 45-50°C. Mix well and pour into sterile Petri plates. Test the finished medium for performance using stable, standard control cultures.
06How should it be stored, and what is the shelf life?
Store at 2–8 °C in sealed, dry, clean conditions. 36 months from manufacture date when stored as directed.
07How 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
References
- 1. Terzaghi B. E. and Sandine W. E., 1975. Improved medium for lactic streptococci and their bacteriophages. Appl. Microbiol., 29:807-813.
- 2. ISO 7889 / IDF 117, Yogurt — Enumeration of characteristic microorganisms, International Organization for Standardization, Geneva.