WLD Agar (Wallerstein Laboratory Differential Agar)
WLD Agar (Wallerstein Laboratory Differential Agar)
Selective & Differential Medium for Beverage Microbiology
Catalog Number: AS-1319
Pack Sizes: 500 g, 1 kg
Overview
WLD Agar (Wallerstein Laboratory Differential Agar) is a selective and differential solid culture 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 the detection of lactic acid bacteria, including Lactobacillus and Pediococcus, and for differentiating bacterial contaminants from yeast flora based on characteristic colony coloration and growth patterns.
WLD Agar is widely used for routine microbiological quality control and hygiene monitoring in fermentation-based industries.
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
Key Features & Benefits
• Selective formulation for recovery of brewery and winery bacteria
• Differential indicator system for visualising acid production
• Suppresses brewing yeast to improve detection of bacterial contaminants
• Suitable for routine QC testing and contamination investigations
• Widely recognised standard medium in beverage microbiology
Principle of the Medium
WLD Agar selectively recovers brewery and winery bacteria, including lactic acid bacteria and acetic acid bacteria, while cycloheximide suppresses the growth of brewing yeast. Acid production from carbohydrate fermentation is visualised by bromocresol green, allowing clear differentiation of bacterial colonies based on colour change.
The medium contains a nutritionally rich base with glucose, yeast extract, and casein hydrolysate, balanced with potassium, magnesium, calcium salts, and trace iron and manganese to support growth of fastidious beverage-associated microorganisms.
Typical Composition (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
(Composition may be adjusted to meet specific institutional or published standards.)
Preparation
Suspend the required amount of dehydrated medium in purified water according to the formulation.
Heat with agitation until completely dissolved.
Sterilize by autoclaving at 121 °C for 15 minutes.
Cool to 45–50 °C, mix gently, and pour plates.
Allow plates to solidify and dry before use.
Incubation
Incubate plates at 25–30 °C for 3–5 days, or as required by the target organisms and testing protocol.
Storage & Stability
Dehydrated medium: Store tightly sealed at 15–25 °C, protected from moisture and light
Prepared plates: Store at 2–8 °C and use within recommended holding time
Shelf life: 36 months from date of manufacture, unopened
Intended Use
For laboratory research and industrial microbiological quality control use only.
Not for human, veterinary, food, feed, or pharmaceutical use.
Quality & Compliance
Manufactured under controlled conditions to ensure batch-to-batch consistency.
Suitable for brewery, winery, beverage, and fermentation microbiology.
Performance comparable to leading international culture media suppliers.
Customs & Trade Information
HS / AHECC Code: 3821.00.00
Prepared culture media for the development or maintenance of microorganisms