Dichloran-Glycerol (DG18) Agar 500 gr, Oxoid CM0729

Description Dichloran-Glycerol (DG18) Agar Base is based on the formulation described by Hocking and Pitt1 and is recommended for the enumeration and isolation of xerophilic moulds from dried and semi-dried foods. Examples of these are dried fruits, spices, confectionery, cereals, nuts and dried meat and fish products. The medium formulation contains glycerol at 16% (w/w) which lowers the water activity (aW) from 0.999 to 0.95. Glycerol was chosen because of advantages it showed over sodium chloride and sugars which have traditionally been used to formulate media of reduced aW1. The medium also contains dichloran which inhibits spreading of mucoraceous fungi and restricts the colony size of other genera. This restrictive characteristic makes the medium especially suitable for enumeration because it allows unobscured growth of organisms that ordinarily form small colonies. A modification to the formula has been described in which the addition of Triton-X to DG18 agar increases the inhibition of vigorously-spreading fungi2. In a comparative study carried out between DG18 and DRBC, (a medium of higher aW ) greater recovery of xerophilic moulds was achieved on the DG18 medium1. In this study it was found that two of the fungi commonly isolated from dried foods in high numbers, Aspergillus penicilloides and Wallemia sebi, grow very poorly or not at all on DRBC.