Maintenance Medium for B. subtilis ATCC 6633

Maintenance Medium for B. subtilis ATCC 6633

Maintenance Medium is used for maintenance of Bacillus subtilis ATCC 6633 used as test organism for microbiological assay of antibiotics.

Composition**

Final pH (at 25°C) 6.6±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 30.5 grams in 1000 ml distilled water. Heat to boiling to dissolve the medium completely. Dispense as desired and sterilize by autoclaving at at 15 lbs pressure (121°C) for 15 minutes.

Principle And Interpretation

Maintenance Medium is used for the maintenance of Bacillus subtilis ATCC 6633 used as test organisms for microbiological assay of antibiotics (1). Maintenance Medium contains peptic digest of animal tissue, casein enzymic hydroylsate and beef extract to provide carbon and nitrogen for general requirements. Yeast extract supplies B-complex vitamins which stimulate bacterial growth. Dextrose is the carbohydrate source. Agar is the solidifying agent.

Quality Control

Appearance Cream to yellow coloured homogeneous free flowing powder

Gelling Firm, comparable with 1.5% Agar gel

Colour and Clarity of prepared medium Light yellow coloured clear to slightly opalescent gel forms in Petri plates.

Reaction Reaction of 3.05% w/v aqueous solution at 25°C. pH : 6.6±0.2

pH 6.40-6.80

Cultural Response M418: Cultural characteristics observed after an incubation at 35-37°C for 18-48 hours.

Storage and Shelf Life

Store below 30°C in tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label.

Reference

1. Green and Gray, 1950, Wallerstein Lab. Commun., 13:357.