Deoxycholate Lactose Agar was formulated by Leifson for the detection of coliforms in water, dairy products and other food materials. USBio recommends Violet Red Bile Agar as the medium of choice for isolating coliforms from food products. Growth of coliforms which ferment lactose produce red colonies surrounded by a zone of red precipitate. The fermentation of lactose produces acid products which lowers the pH of the medium and the neutral red dye in the medium turns bright red. Sodium citrate and sodium deoxycholate are added to inhibit the growth of Gram positive bacteria.

Light pinkish-beige, homogeneous, free flowing powder

Reddish-pink, clear, complete after autoclaving

As Reported

Dissolve 42.5 grams in 800-900ml of ddH2O stirring gently with heating until completely solubilized. Adjust pH of the medium to the desired level. Add additional water to bring the solution to 1L. Dispense into appropriate containers, loosen caps and autoclave for 15 minutes at 121ºC (15psi).

Store powdered media at RT. Stable for 12 months after receipt. Opened bottles should be capped tightly and kept in a dark, low humidity environment. Prepared media should be kept at 4°C and used within a short period of time.