Part of Thermo Fisher Scientific

Thermo Scentific
 
 
 

Material Safety Data Sheet

Optional Products

Organisms

Organisms this product works with:

Dehydrated Culture Media

UNIVERSAL BEER AGAR

Code: CM0651

For the isolation of beer spoilage organisms.

Typical Formula*

gm/litre

Peptonised milk

15.0

Yeast extract

6.1

Glucose

16.1

Tomato supplement

12.2

Dipotassium hydrogen phosphate

0.31

Potassium dihydrogen phosphate

0.31

Sodium chloride

0.006

Iron (II) sulphate †

0.006

Manganese (II) sulphate

0.006

Magnesium sulphate

0.12

Agar

12.0

pH 6.1 ± 0.2 @ 25°C

 
* Adjusted as required to meet performance standards
† Iron (II) sulphate = ferrous sulphate 

Directions
Suspend 62g in 750ml of distilled water and bring to the boil to dissolve completely. Add 250ml beer, without degassing, to the hot medium and mix gently. Distribute into final containers and sterilise by autoclaving at 121°C for 10 minutes.

Description
Universal Beer Agar is presented as a basal medium to which beer alone or beer and cycloheximide may be added for the detection and culture of microbial contaminants in beer. The medium is based on the formula developed by Kozulis and Page1, who recommended that beer must be incorporated in the medium in order to increase selectivity by stimulating the growth of beer spoilage organisms. The presence of hop constituents and alcohol eliminates many airborne contaminants not originating in pitching yeasts, wort or beer; thus minimising false positive results.

Oxoid Universal Beer Agar supports the growth of Lactobacilli, Pediococci, Acetobacter, Zymomonas spp. and wild yeast strains which may be found infecting the pitching yeast, the cooled wort, or during fermentation or storage of the finished beer.

Technique
The presence of microbial spoilage organisms in pitching yeast, the cooled wort or beer in storage may be detected and enumerated using Universal Beer Agar. Either direct surface plating or pour plate techniques with serial dilutions of the sample can be employed. Plates are incubated both aerobically to detect Acetobacter species and anaerobically to detect the micro-aerophilic Lactobacilli and Pediococci species as well as the anaerobic Zymomonas sp. Plates are incubated at 28-30°C for three days and examined daily.

To increase the differentiation of the colonies, Bromocresol Green (20mg/litre) and powdered chalk (3g/litre) may be added to the medium before sterilisation2. Zones of decolorisation are seen around Pediococcus and some Lactobacillus colonies.

The addition of cycloheximide (SR0222) at 0.001g/litre to suppress yeast growth gives a medium that is selective for the detection of bacterial contaminants in yeast cultures.

Storage conditions and Shelf Life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Appearance
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Orange/straw coloured gel

Quality control

Positive control:

Expected results

Lactobacillus fermentum ATCC® 9338

Good growth; straw coloured colonies

Negative control:

 

Saccharomyces cerevisciae ATCC® 9763*
(when cycloheximide is added to the medium)

Inhibited

* This organism is available as a Culti-Loop®

Precautions
When handling cycloheximide observe the precautions to be taken under HAZARDS.

References
1. Kozulis J. A. and Page H. E. (1968) Proc. Am. Soc. Brew. Chem. 52-58.
2. Boatwright J. and Kirsop B. H. (1976) J. Inst. Brew. 82. 343-346.

 
©2001 - 2021 Oxoid Limited, All rights reserved.
Copyright, Disclaimer and Privacy Policy | Conditions of Sale | About Us | Cookies
Thermo Fisher Scientific Inc.