Rogosa SL Agar and Broth

Intended Use

Rogosa SL Agar and Rogosa SL Broth are used for cultivating oral, vaginal and fecal lactobacilli.

Summary and Explanation

Rogosa SL Agar and Broth, also known as RMW Agar/Broth, are a modification of media described by Rogosa, Mitchell and Wiseman.1,2 These media are used for isolation, enumeration and identification of lactobacilli in oral bacteriology, feces, vaginal specimens and foodstuffs.3,4 The low pH and high acetate concentrations effectively suppress other bacterial flora allowing lactobacilli to flourish.

Principles of the Procedure

Peptone provides carbon and nitrogen. Yeast extract is a source of trace elements, vitamins and amino acids. Dextrose, arabinose and saccharose are carbohydrate sources that
provide carbon. Sodium acetate and ammonium citrate inhibit streptococci, molds and other oral microbial flora and restrict swarming. Monopotassium phosphate provides buffering capability. Magnesium sulfate, manganese sulfate and ferrous sulfate are sources of inorganic ions. Polysorbate 80 acts as a surfactant. Agar is the solidifying agent.

User Quality Control

Identity Specifications
Rogosa SL Agar
Dehydrated Appearance: Beige, homogeneous with soft clumps.
Solution:                       7.5% solution, soluble in purified water upon
                                    boiling. Solution is light amber, slightly opalescent
                                    and may have a slight precipitate.
Prepared Appearance:     Light amber, slightly opalescent.
Reaction of 7.5% Solution
(with glacial acetic acid
and reboiling) at 25°C:    pH 5.4 ± 0.2
Rogosa SL Broth
Dehydrated Appearance: Beige, appears moist, with soft clumps.
Solution:                       6.0% solution, soluble in purified water upon
                                   boiling. Solution is light amber, clear to slightly
                                   opalescent.
Prepared Appearance:    Light amber, clear to slightly opalescent.
Reaction of 6.0% Solution
(with glacial acetic acid
and reboiling) at 25°C:   pH 5.4 ± 0.2
Cultural Response
Rogosa SL Agar or Rogosa SL Broth
Prepare the medium per label directions. Inoculate the agar medium using the pour plate technique and incubate at 35 ± 2°C for 40-48 hours. Inoculate the broth medium and incubate at 35 ± 2°C for 18-48 hours.

Formula

Rogosa SL Agar
Approximate Formula* Per Liter
Tryptone.................................................................... 10.0 g
Yeast Extract................................................................ 5.0 g
Dextrose.................................................................... 10.0 g
Arabinose.................................................................... 5.0 g
Saccharose........................................................ .......... 5.0 g
Sodium Acetate........................................................... 15.0 g
Ammonium Citrate........................................................ 2.0 g
Monopotassium Phosphate............................................ 6.0 g
Magnesium Sulfate...................................................... 0.57 g
Manganese Sulfate...................................................... 0.12 g
Ferrous Sulfate............................................................ 0.03 g
Polysorbate 80............................................................. 1.0 g
Agar.......................................................................... 15.0 g
Rogosa SL Broth
Consists of the same ingredients without the agar.
*Adjusted and/or supplemented as required to meet performance criteria.

Directions for Preparation from Dehydrated Product

1. Suspend the powder in 1 L of purified water:
    Difco™ Rogosa SL Agar – 75 g;
    Difco™ Rogosa SL Broth – 59.7 g. Mix thoroughly.
2. Heat with frequent agitation and boil for 1 minute to completely dissolve the powder.
3. Add 1.32 mL of glacial acetic acid and mix thoroughly.
4. Boil for 2-3 minutes. DO NOT AUTOCLAVE.
5. Test samples of the finished product for performance using stable, typical control cultures.

Procedure

See appropriate references for specific procedures.

Expected Results

Refer to appropriate references and procedures for results.

Limitation of the Procedure

The salt in the formulation makes the media unsuitable for isolation of dairy lactobacilli; e.g., L. lactis, L. bulgaricus and L. helveticus.4

*Store at 2-8°C.

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