Dichloran-Glycerol Agar (DG18)

Dichloran-Glycerol Agar (DG18)

Selective Medium for Enumeration of Xerophilic Moulds

Product Identification

General Information

Product Name: Dichloran-Glycerol Agar (DG18)
Catalogue Number: AS-1206
Medium Type: Selective fungal culture medium
Form: Dehydrated powder

Product Overview

Dichloran-Glycerol Agar (DG18) is a selective solid culture medium designed for the isolation and enumeration of xerophilic moulds, particularly from semi-dried and dried food products.

The medium contains 18% glycerol, reducing water activity (aᵥ) to approximately 0.95, which suppresses bacterial growth while supporting xerophilic and osmophilic fungi. Chloramphenicol further inhibits bacterial contaminants, while dichloran restricts the spread of fast-growing mucoraceous fungi, enabling accurate colony counting.

DG18 is widely used in food microbiology, environmental monitoring, and mycological research, and is referenced in international standards for dried and low-moisture foods.

Principle of the Medium

Functional Components

Glycerol (18%): Lowers water activity to favour xerophilic fungi
Dichloran: Restricts colony size of rapidly spreading moulds
Chloramphenicol: Suppresses bacterial contamination
Peptone & Dextrose: Provide carbon and nitrogen sources
Potassium Phosphate: Buffers the medium
Magnesium Sulfate: Supplies essential ions

Applications

Food & Environmental Microbiology

Enumeration of xerophilic moulds in dried and semi-dried foods
Microbiological analysis of cereals, spices, nuts, dried fruits, and confectionery

Mycology & Research

Isolation of osmophilic and xerophilic fungi
Accurate colony counting in mixed fungal populations

Key Features

Performance Advantages

Reduced water activity (~0.95) for selective fungal growth
Dichloran limits colony spread for accurate enumeration
Chloramphenicol suppresses bacterial interference
Excellent clarity and reproducibility
Suitable for routine QC and research laboratories

Typical Composition (per litre)

Formulation Information

Peptone
Dextrose
Glycerol (18%)
Potassium Phosphate
Magnesium Sulfate
Dichloran
Chloramphenicol
Agar

(Final pH adjusted to specification after preparation)

Preparation Guidelines

General Preparation

Suspend the required amount of dehydrated medium in purified water
Heat with agitation until fully dissolved
Sterilise by autoclaving at 121 °C for 15 minutes
Cool to 45–50 °C and pour into sterile Petri dishes

Storage & Stability

Storage Conditions

Dehydrated medium: Store at 15–30 °C, dry and tightly sealed
Prepared medium: Store at 2–8 °C

Do not use if contamination, clumping, or dehydration is observed.

Intended Use & Safety

Regulatory Statement

For laboratory use only.
Not intended for medical, veterinary, or food consumption.

Refer to the Safety Data Sheet (SDS) before use.