D.C.A (LEIFSON,S)Agar 500 gr

.C.A.(Desoxycholate Citrate Agar)LAB 29DescriptionThis is Leifson’s original formulation of this selective medium for the isolation of Salmonella spp. and Shigella spp. from faeces andenvironmental samples. It has approximately half the quantity of inhibitors used in the Hynes modification. The medium uses sodiumcitrate and sodium desoxycholate as inhibitors. Sodium thiosulphate is the substrate for the enzyme thiosulphate reductase being brokendown to form sulphite and hydrogen sulphide. The hydrogen sulphide reacts with the ferric ions to produce a black precipitate of ferroussulphide. This gives a typical black centre to the colonies of most species of Salmonella.Typical Formula g/litreBeef Extract 5.0Balanced Peptone No. 1 5.0Lactose 10.0Sodiumcitrate 5.0Sodium thiosulphate 5.0Ferric citrate 1.0Sodium desoxycholate 2.5Neutral Red 0.025Agar No. 2 12.0Method for reconstitution