Selective Medium · Lactic Acid Bacteria
Rogosa Agar (LBS Agar)
Acidified selective medium for the isolation and enumeration of lactobacilli from dairy, fermented foods, probiotics, oral and faecal samples.
Cat. No. AS-139974.73 g/LpH 5.4 ± 0.2Selective AgarDo Not Autoclave
Key principle: a low pH (5.4) combined with a high acetate concentration suppresses most accompanying flora, while lactobacilli, which tolerate acid and acetate, grow well.
At a Glance
FormatDehydrated powder
Use rate74.73 g/L
Acid addition1.32 mL/L acetic acid
Heat treatmentBoil 2–3 min
Incubation35–37 °C, 2–3 days
AtmosphereAnaerobic / CO₂
Intended Use
Rogosa Agar (LBS Agar) is a selective medium for the isolation, cultivation and enumeration of Lactobacillus and related lactic acid bacteria (including Lacticaseibacillus, Lactiplantibacillus and Limosilactobacillus) from foods, dairy products, probiotic preparations, and oral and faecal specimens.
For laboratory microbiological testing, quality control and research use only. Not intended for direct use in food, human or veterinary therapeutic applications, diagnosis, or consumption.
Principle & Biochemistry
Casein peptone and yeast extract supply nitrogen, vitamins and growth factors. D-Glucose is the fermentable carbon and energy source. Polysorbate 80 provides oleic acid, which stimulates the growth of many lactobacilli. Magnesium, manganese and iron salts are essential cofactors; manganese is particularly important for lactobacilli, which use it to protect against oxidative stress.
Selectivity comes from the acetate buffer system. High sodium acetate, together with glacial acetic acid added during preparation, gives a final pH of 5.4. At this pH, a large fraction of the acetate is undissociated acetic acid, which crosses bacterial membranes and inhibits most Gram-negative bacteria, streptococci, staphylococci and many yeasts. Ammonium citrate adds further inhibition. Lactobacilli tolerate both the low pH and the acetate, so they grow selectively.
Formulation (g/L)
| Ingredient | g/L |
|---|---|
| Casein Peptone (Tryptone) | 10.0 |
| Yeast Extract | 5.0 |
| D-Glucose | 20.0 |
| Polysorbate 80 (Tween 80) | 1.0 |
| Potassium Dihydrogen Phosphate | 6.0 |
| Sodium Acetate | 15.0 |
| Ammonium Citrate | 2.0 |
| Magnesium Sulfate·7H₂O | 0.575 |
| Manganese Sulfate·4H₂O | 0.12 |
| Iron(II) Sulfate·7H₂O | 0.034 |
| Agar | 15.0 |
| Total | 74.73 |
Merck-type LBS formulation. Selective agents shown in amber. Final pH 5.4 ± 0.2 at 25 °C after the addition of glacial acetic acid. Formula may be adjusted to meet performance standards.
Key Applications
Dairy & Fermented FoodsEnumeration of lactobacilli in yoghurt, cheese, fermented milks, sourdough and fermented vegetables.
Probiotic ProductsCounting Lactobacillus and related genera in probiotic powders, capsules and starter cultures.
Oral & Gut ResearchIsolation of lactobacilli from saliva, dental plaque and faecal samples in research settings.
Spoilage InvestigationDetection of lactobacilli in beer, wine, juices and meat products.
Teaching LaboratoriesDemonstrating selective media and acid tolerance in university and TAFE practicals.
Strain MaintenanceSelective recovery of lactobacilli from mixed cultures and environmental samples.
Advantages & Considerations
Advantages
- High selectivity against Gram-negative and most Gram-positive flora
- Supports good recovery of acid-tolerant lactobacilli
- No autoclaving required, which saves time
- Well-established formulation with decades of published use
Considerations
- Not fully specific: some pediococci, leuconostocs, enterococci and yeasts may grow
- Some fastidious or acid-sensitive lactobacilli may be partially inhibited
- Confirm isolates by Gram stain, catalase test and identification methods
- Overheating or autoclaving softens the gel
Typical Colony Appearance
| Organism | Growth | Colony appearance |
|---|---|---|
| Lactobacillus spp. and related genera | Good | Small, white to cream, smooth or rough, 1–3 mm |
| Escherichia coli | Inhibited | — |
| Staphylococcus aureus | Inhibited | — |
Comparable Products
| Supplier | Product | Cat. No. | Note |
|---|---|---|---|
| Merck / Millipore | ROGOSA agar | 105413 | Comparable published formulation |
| HiMedia | Rogosa SL Agar | M130 | Comparable; carbohydrate source split into glucose, arabinose and sucrose |
Catalogue numbers are listed for user reference only. Users should verify suitability for their own method.
Related Standards (for user reference)
- Rogosa M., Mitchell J.A. and Wiseman R.F. (1951): original description of the medium
- APHA Compendium of Methods for the Microbiological Examination of Foods
- APHA Standard Methods for the Examination of Dairy Products
Frequently Asked Questions
Why must Rogosa Agar not be autoclaved?
At pH 5.4, autoclave temperatures hydrolyse the agar and the gel becomes soft. The published method uses boiling for 2–3 minutes instead.
Is a broth version available?
Yes. AS-1451 Rogosa Broth (LBS) has the same formulation without agar. AS-1407 Rogosa SL Broth uses a glucose, arabinose and sucrose carbohydrate mix.
What is the difference between Rogosa Agar and MRS Agar?
MRS Agar (pH 6.2) is a general, non-selective medium for lactic acid bacteria. Rogosa Agar (pH 5.4) is selective for lactobacilli because of its lower pH and higher acetate content.
Which incubation conditions should be used?
Incubate at 35–37 °C for 48–72 hours under anaerobic conditions or with 5–10% CO₂. Lower temperatures (e.g. 30 °C) may suit some food-derived strains.
Technical Specifications
| Catalogue No. | AS-1399 |
| Product type | Dehydrated culture medium |
| Appearance (powder) | Cream to light yellow, free-flowing |
| Appearance (prepared) | Light yellow to amber, clear to slightly opalescent |
| Use rate | 74.73 g/L |
| Final pH | 5.4 ± 0.2 at 25 °C |
| Heat treatment | Boil 2–3 min. Do not autoclave. |
| Pack size | 500 g |
| Storage (powder) | 2–8 °C, dry, tightly closed |
| Documents | TDS, SDS; batch COA on request |
Applications
- Dairy and fermented food testing
- Probiotic product enumeration
- Oral and faecal microbiology research
- Beverage spoilage investigation
- Teaching laboratories
Preparation
- Suspend 74.73 g in 1 L of purified water.
- Heat with frequent stirring until fully dissolved.
- Add 1.32 mL of glacial acetic acid and mix well.
- Boil for 2–3 minutes. Do not autoclave.
- Cool to 45–50 °C and pour into sterile Petri dishes.
- Check the pH of a cooled sample: 5.4 ± 0.2 at 25 °C.
Glacial acetic acid is corrosive and flammable. Handle it in a fume hood and wear gloves and eye protection.
Storage & Stability
Store the dehydrated medium at 2–8 °C in a dry place, tightly closed and protected from light. The powder is hygroscopic. Use before the expiry date on the label. Store prepared plates at 2–8 °C protected from light, and use them promptly.
Technical Data Sheet — Rogosa Agar (LBS Agar)
TDS-AS-1399 · Rev 1.0 · November 20261. Product Identification
| Product name | Rogosa Agar (LBS Agar) |
| Catalogue No. | AS-1399 |
| Product type | Dehydrated microbiological culture medium |
| Manufacturer | Ausamics Pty Ltd, Epping, VIC, Australia |
2. Intended Use
Selective isolation, cultivation and enumeration of lactobacilli and related lactic acid bacteria from foods, dairy products, probiotic preparations, and oral and faecal samples. For laboratory use only.
3. Mode of Action
Sodium acetate and added acetic acid create an acetate buffer at pH 5.4. Undissociated acetic acid inhibits most Gram-negative bacteria and many Gram-positive bacteria, and ammonium citrate adds further inhibition. Acid-tolerant lactobacilli grow using glucose, peptones, yeast extract, Tween 80 and essential metal ions.
4. Formulation (g/L)
| Ingredient | g/L |
|---|---|
| Casein Peptone (Tryptone) | 10.0 |
| Yeast Extract | 5.0 |
| D-Glucose | 20.0 |
| Polysorbate 80 (Tween 80) | 1.0 |
| Potassium Dihydrogen Phosphate | 6.0 |
| Sodium Acetate | 15.0 |
| Ammonium Citrate | 2.0 |
| Magnesium Sulfate·7H₂O | 0.575 |
| Manganese Sulfate·4H₂O | 0.12 |
| Iron(II) Sulfate·7H₂O | 0.034 |
| Agar | 15.0 |
| Total | 74.73 |
5. Physical Specifications
| Powder appearance | Cream to light yellow, homogeneous, free-flowing |
| Prepared medium | Light yellow to amber, clear to slightly opalescent gel |
| Gel | Firm, comparable to 1.5% agar |
| Final pH (25 °C) | 5.4 ± 0.2 (after acetic acid addition) |
6. Preparation
- Suspend 74.73 g of powder in 1 L of purified water.
- Heat with frequent stirring until completely dissolved.
- Add 1.32 mL of glacial acetic acid and mix thoroughly.
- Boil for 2–3 minutes. Do not autoclave.
- Cool to 45–50 °C and pour into sterile Petri dishes.
7. Quality Control (Performance)
Incubation: 35–37 °C, 48–72 h, anaerobic or 5–10% CO₂.
| Organism | Strain | Inoculum (CFU) | Expected result |
|---|---|---|---|
| Lacticaseibacillus rhamnosus | ATCC 9595 | ≤100 | Good growth, white–cream colonies |
| Limosilactobacillus fermentum | ATCC 9338 | ≤100 | Good growth |
| Lactiplantibacillus plantarum | ATCC 8014 | ≤100 | Good growth |
| Escherichia coli | ATCC 25922 | ≥10⁴ | Inhibited |
| Staphylococcus aureus | ATCC 25923 | ≥10⁴ | Inhibited |
8. Storage & Shelf Life
Dehydrated medium: 2–8 °C, dry, tightly closed, protected from light. Use before the expiry date on the label. Prepared plates: 2–8 °C, protected from light; use promptly.
9. Limitations
Some pediococci, leuconostocs, enterococci, bifidobacteria and yeasts may grow. Some lactobacilli may grow poorly. Confirm presumptive isolates with appropriate identification methods.
10. References
- Rogosa M., Mitchell J.A., Wiseman R.F. (1951). A selective medium for the isolation and enumeration of oral and fecal lactobacilli. J. Bacteriol. 62:132–133.
- Rogosa M., Mitchell J.A., Wiseman R.F. (1951). A selective medium for the isolation and enumeration of oral lactobacilli. J. Dent. Res. 30:682–689.
- Salfinger Y., Tortorello M.L. (eds) (2015). Compendium of Methods for the Microbiological Examination of Foods, 5th ed. APHA.
- Zheng J. et al. (2020). A taxonomic note on the genus Lactobacillus. Int. J. Syst. Evol. Microbiol. 70:2782–2858.
Safety Data Summary — Rogosa Agar (LBS Agar)
SDS-AS-1399 · Rev 1.0 · November 2026 · Full 16-section SDS available on requestHazard Classification
Not classified as hazardous according to the criteria of the GHS (Rev. 7) as adopted under the Australian Work Health and Safety Regulations. No hazard pictogram or signal word is required.
The glacial acetic acid added during preparation is not part of this product. It is a hazardous chemical (flammable, causes severe skin burns and eye damage). Refer to its own SDS.
Handling & Protection
- Avoid creating and breathing dust. Use with adequate ventilation.
- Wear laboratory coat, gloves and safety glasses.
- Wash hands after handling.
First Aid
- Inhalation: Move to fresh air.
- Skin: Wash with soap and water.
- Eyes: Rinse with water for several minutes. Seek medical advice if irritation persists.
- Ingestion: Rinse mouth. Seek medical advice if feeling unwell.
Poisons Information Centre (Australia): 13 11 26 · Emergency: 000
Storage & Disposal
Store at 2–8 °C, dry and tightly closed. Dispose of unused powder according to local regulations. Autoclave or otherwise decontaminate used plates before disposal as biological waste.
Transport
Not regulated as dangerous goods for road (ADG), sea (IMDG) or air (IATA) transport.
Quality & Certificate of Analysis
AS-1399 · Batch-specific COA available on requestEach batch of Rogosa Agar is manufactured in Melbourne and tested internally before release. A batch-specific Certificate of Analysis is available on request. Please quote the batch number printed on the label.
Release Specifications
| Test | Specification |
|---|---|
| Appearance (powder) | Cream to light yellow, homogeneous, free-flowing |
| Appearance (prepared) | Light yellow to amber, clear to slightly opalescent |
| Gel | Firm, comparable to 1.5% agar |
| pH (25 °C, after acid addition) | 5.2 – 5.6 |
| Growth: L. rhamnosus ATCC 9595 | Good growth |
| Growth: L. plantarum ATCC 8014 | Good growth |
| Inhibition: E. coli ATCC 25922 | Inhibited |
| Inhibition: S. aureus ATCC 25923 | Inhibited |