(AB) LSB, 500 grams

Use: Broth medium recommended for the detection of coliforms in water, wastewater and foods.

Description: Lauryl Sulfate Broth was formulated by Malimann and Darby for detection of coliform bacteria in water. This is a selective medium because it contains sodium lauryl sulfate which inhibits Gram positive microorganisms. Lactose is added to detect rapid lactose fermentation by coliforms.

Formula* per Liter:

• Casein Digest Peptone ............. 20.0g
• Potassium Phosphate, Monobasic. 2.75g
• Lactose .......................................... 5.0g
• Potassium Phosphate, Dibasic....... 2.75g
• Sodium Chloride ............................5.0g
• Sodium Lauryl Sulfate ........................ 0.1g

Final pH: 6.8 ± 0.2 at 25.0°C

* Grams per liter may be adj. or formula supplemented to obtain desired performance

Preparation: Mix 35.6 grams of the medium in one Liter of purified water until evenly dispersed. Prepare double strength broth for evaluating 10 mL samples. Distribute into test tubes containing inverted Durham tubes and autoclave at 121.0°C for 15 minutes.

Quality Control Specifications:

1. The powder is homogeneous, free flowing and light beige.
2. Visually the prepared medium is yellow to gold and clear to trace hazy.
3. Expected cultural response after 18-24 hours at 35.0°C.

Organism                                                                                Result

Enterobacter aerogenes ATCC 13048                              Growth, Gas +

Escherichia coli ATCC 25922                                           Growth, Gas +

Proteus mirabilis ATCC 12453                                           Growth, Gas -

Salmonella typhimurium ATCC 14028                               Growth, Gas -

Staphylococcus aureus ATCC 25923                                 No Growth

Storage: Store the sealed bottle containing the dehydrated medium at 2 to 30.0°C. Once opened and recapped, place the container in a low humidity environment at the same storage temperature. Protect it from moisture and light. The dehydrated medium should be discarded if it is not free flowing or if the color has changed from the original light beige color.