BRYANT BURKEY BROTH BASE (WITH RESAZURIN)

A liquid medium for the enumeration of spores of lactate fermenting Clostridia.

Code: CB1/3291

Typical formula g/l

Tryptone	15.0
Yeast extract	5.0
Beef extract	7.5
Sodium acetate	5.0
Cysteine HCl	0.5
Resazurin	2.5 mg

pH 5.9 ± 0.1

Directions

Suspend 33 g in 1000 ml of cold distilled water; add 10 g of 50% sodium lactate solution. Heat to dissolve stirring constantly. Distribute 10ml in 16x160mm tubes. Autoclave at 121°C for 15 minutes.

Description

Bryant Burkey Broth Base (with Resazurin) is recommended for the enumeration of spores of lactate fermenting clostridia in milk and dairy products, especially Clostridium tyrobutyricum responsible for the browning of cheeses.

Method

Cool the tubes to 25°C after autoclaving or regenerate the anaerobic conditions by heating if the medium is pink for more than 1/3 of its height under surface.

Inoculate 1 ml of the tenfold dilutions of the sample.

Pour paraffin at 58-60°C, previously sterilised at 121°C for 20 minutes.

Heat the tubes at 75°C for 15 minutes to destroy vegetative cells.

Cool in an ice-bath to solidify the paraffin.

Incubate at 37°C for 7 days.

Tubes with growth and gas are to be considered as positive.

User quality assurance (48 h-37°C)

Productivity control

C.tyrobutyricum: growth

Storage

Dehydrated medium: 15-30°C

User prepared tubes: 1 month at 2-8°C (regenerate at 100°C for 20 min before use)

References

Bryant, M.P., Burkey, L.A. (1956) J. Bact., 71, 43-46

Bergère, J.L., Gronet, P., Hermier, P. Moquot, A. (1968) Ann. Inst. Pasteur Lille, 19, 41-54