Universal Beer Agar

Product information

Universal Beer Agar was developed by Kozulis and Page, and used as a basal medium supplemented with beer.1 The developers compared this formula with other media commonly used in breweries for detecting microbial contamination.2 The characteristics of Universal Beer Agar are closer to natural environmental conditions found in a typical brewery. Universal Beer Agar supports the growth of more lactic acid bacteria and yields larger colonies in a shorter time than traditional brewer’s media. Supplementing this medium with beer has produced a selective environment for organisms that are adapted to existent conditions in the brewery. The presence of hop constituents and alcohol inhibits growth of many airborne microorganisms not adapted to this environment.3
Universal Beer Agar supports growth of Lactobacillus, Pediococcus, Acetobacter, and yeasts that are known beer contaminants. Universal Beer Agar is abbreviated as UBA.
Principles of the Procedure
Tomato Juice Solids is a source of carbon, protein, and nutrients. Yeast Extract provides trace elements, vitamins, and amino acids. Dextrose supplies additional carbon. Dipotassium Phosphate and Monopotassium Phosphate are the buffers. Magnesium Sulfate, Ferrous Sulfate, and Manganese Sulfate are sources of ions that stimulate metabolism. Sodium Chloride maintains the osmotic balance of the medium. Peptonized Milk contains lactose as an energy source. Agar is the solidifying agent.
Formula / Liter
Tomato Juice Solids.................................................................7 g
Yeast Extract..........................................................................10 g
Dextrose.................................................................................10 g
Dipotassium Phosphate.........................................................0.5 g
Monopotassium Phosphate...................................................0.5 g
Magnesium Sulfate............................................................0.125 g
Sodium Chloride..................................................................0.01 g
Ferrous Sulfate....................................................................0.01 g
Manganese Sulfate..............................................................0.01 g
Peptonized Milk......................................................................15 g
Agar........................................................................................12 g
Final pH: 6.3 ± 0.2 at 25°C
Formula may be adjusted and/or supplemented as required to meet performance specifications.
Precaution
1. For Laboratory Use.
Directions
1. Suspend 55 g of the medium in 750 mL of purified water.
2. Heat with frequent agitation and boil for one minute to completely dissolve the medium.
3. While medium is hot, add and mix 250 mL of beer without degassing.
4. Autoclave at 121°C for 10 minutes.