: Selective & Differential
: Selects for Gm(-) mircoorganisms, differentiates for lactose fermenters (Desoxycholate Agar is inhibitory for the growth of Gm(+) microorganisms)
: Lactose, Desoxycholate (detergent)
: Red Dye is absorbed into acid producing colony during lactose ferm.
: Red Colony=Lactose (+), Non-Red Colony=Lactose (-)
Lactose fermenters produce acid, which preceipitates the bile salts in the media and absorbs the neutral red dye, therefore appearing red. Non-fermenters do not do this and do not appear red.