Brettanomyces Agar Base

Brettanomyces Agar Base is used for the cultivation of Brettanomyces species.

Composition**

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 41.21 grams in 1000 ml distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45 - 50°C. Aseptically add sterile rehydrated contents of 1 vial of Brettanomyces Selective Supplement (FD228). Mix well and pour into sterile Petri plates.

Principle And Interpretation

Yeast accounts for most of the spoilage problems in the soft drink industry due to their high acid tolerance and ability to grow anaerobically. Brettanomyces is one the yeast species found in soft drinks. Brettanomyces species are sensitive to benzoic and sorbic acids but are highly resistant to carbonation. This yeast has been implicated in the spoilage of low and non-preserved diet beverages, flavoured carbonated waters as well as sugar sweetened products.

Brettanomyces Selective Media is recommended by APHA (1) for isolation and cultivation of Brettanomyces species. Brettanomyces Agar Base is similar to Brettanomyces Selective Media with the addition of agar.

Peptone, malt extract and yeast extract provide essential growth nutrients for the growth of Brettanomyces species. Dextrose is the suitable carbohydrate source. The antibiotics supplement suppresses the growth of accompanying bacteria.

Quality Control

Appearance: Cream to yellow homogeneous free flowing powder

Gelling: Firm, comparable with 2.0% agar gel.

Colour and Clarity of prepared medium: Light amber coloured, slightly opalescent gel forms in Petri plates

Cultural Response: M1585: Cultural characteristics observed with added Brettanomyces Selective Supplement(FD228) after an incubation at 25-30°C for 3-5 days.

Storage and Shelf Life

Store between 15-25°C in tightly closed container and prepared medium at 2-8°C. Use before expiry date on the label.

Reference

1. Downes I. P. and Ito K. (ed.). 2001. Compendium of methods for the Microbiological Examination of foods, 4th ed. American Public Health Association, Washington, D.C.