WLD Agar (Wallerstein Laboratory Differential Agar)
 
CAT No.: AS-1319 | Pack sizes: 500 g, 1 kg
 
Description
WLD Agar (Wallerstein Laboratory Differential Agar) is a selective and differential medium designed for the isolation and enumeration of bacteria, yeasts, and molds commonly encountered in breweries, wineries, and other beverage production environments. It is particularly effective for detecting lactic acid bacteria (Lactobacillus, Pediococcus) and differentiating them from yeast flora through characteristic colony coloration and growth patterns.
 
Applications
Quality control in breweries, wineries, and soft drink production
Detection of lactic acid bacteria and other spoilage organisms
Routine microbiological monitoring of fermentation processes
Differentiation of microbial flora in beverage products
 
Principle
WLD Agar (Wallerstein Laboratory Differential Agar) selectively recovers brewery/winery bacteria (e.g., LAB, acetic acid bacteria) while cycloheximide suppresses brewing yeast. Bromocresol green (0.022 g/L) visualizes acid production, enabling clear differentiation of bacterial colonies on a nutritionally rich base (glucose 50 g/L, YE 4 g/L, casein hydrolysate 5 g/L) balanced with K⁺/Mg²⁺/Ca²⁺ salts and trace Fe/Mn. 
 
Typical Formula (per litre)
Yeast Extract – 4.0 g
Peptone – 5.0 g
Dextrose – 50.0 g
Calcium Chloride – 0.125 g
Monopotassium Phosphate – 0.55 g
Magnesium Sulfate – 0.025 g
Ferrous Chloride – 0.0025 g
Manganese Sulfate – 0.0025 g
Bromocresol Green – 0.022 g
Cycloheximide – 0.004 g
Agar – 20.0 g
Final pH (25 °C): 5.5 ± 0.2
 
Storage & Shelf Life
Store tightly sealed in a cool, dry place (15–25 °C), protected from moisture and light.
Shelf life: 36 months from date of manufacture, unopened.