Universal Liquid Medium

Universal Liquid Medium M1332

This medium is generally used in the brewing industry for the cultivation of brewery bacteria, including beer spoilage forms in the brewing industry

Composition**

Final pH (at 25°C): 6.3±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 50.02 grams in 1000 ml distilled water. Heat if necessary to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 10 minutes. The sterile medium should be stored in the dark at room temperature. Examine any surface film or pellicle microscopically for aerobic bacteria.

Principle And Interpretation

Universal Liquid Medium, Modified is used for cultivation of brewing bacteria. It is a modification of Universal Beer Agar developed as per Kozulis and Page (1). Cycloheximide suppresses certain yeasts.

Yeast extract is a source of trace elements, vitamins and amino acids. Peptonized milk contains lactose as an energy source. Tomato juice is a source of carbon, protein and nutrients. Dextrose provides additional carbon. Dipotassium and monopotassium phosphates provide buffering capability. Magnesium sulphate, ferrous sulphate and manganese sulphate are sources of ions that simulate metabolism. Sodium chloride maintains the osmotic equilibrium.

Quality Control

Appearance: Cream to yellow homogeneous free flowing powder

Colour and Clarity of prepared medium: Medium amber coloured clear solution in tubes

Reaction: Reaction of 5.0% w/v aqueous solution at 25°C. pH: 6.3±0.2

pH: 6.10-6.50

Cultural Response: M1332: Cultural characteristics observed after an incubation at 35-37°C for 40-48 hours.

Storage and Shelf Life

Store below 8°C in tightly closed container.Use before expiry date on the label.

Reference

1. Kozulis J. A. and Page H. E., 1968, Proc. Am. Soc. Brew. Chem., 52:58.