WL Nutrient Agar , 250g

Description: 

Suspend 75g in 1 litre of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes. If required the pH may be adjusted to 6.5 by the addition of 1% sodium bicarbonate solution. 

WL Nutrient Agar (Medium), based on that of Green and Gray 1 is recommended for the determination of the microbiological flora in brewing and fermentation processes. The medium is suitable for the differentiation of `wild’ yeasts from brewing yeasts2. 

Reliable counts for brewers’ yeast are obtained with the medium at pH 5.5. Adjustment to pH 6.5 facilitates the counting of bakers’ and distillers’ yeasts. 

Cycloheximide (SR0222) may be added to the medium at a final concentration of 4 mg/litre, to suppress yeast growth, the medium becomes selective for the bacterial contaminants of yeast cultures. 

When making microbial counts with this medium the time and temperature of incubation will vary according to the materials tested and the organisms sought. Temperatures of 25°C are used for brewing materials and 30°C for bakers’ yeasts 

Specification: 

250g