A selective medium for the detection of E.coli in water and food with MF procedure.

Tryptone	20.0
Yeast extract	5.0
Bile salts No. 3	1.5
Disodium phosphate	5.0
Monopotassium phosphate	1.5
Sodium chloride	5.0
MUG	0.1
Agar	12.0

pH 7.2 +/- 0.2

Suspend 50g in 1000ml of cold distilled water. Heat to boiling with frequent agitation and sterilise by autoclaving at 121°C for 15 minutes.

E. coli Direct AGAR MUG is a selective and differential medium for isolation, enumeration and identification of E.coli. The selective action is obtained with the presence of bile salts, which inhibit the growth of Gram-positive bacteria. E. coli Direct AGAR MUG does not contain lactose and, therefore, the substrate is not acidified during E.coli growth. The obtained fluorescence in this way, having a maximum intensity through an alkaline pH, is more evident than on other media with MUG. E. coli Direct AGAR MUG is prepared with tryptophan-rich peptones in such a way that it is possible the direct determination of indole on the colonies. This medium is recommended for isolation, enumeration and direct identification of E.coli using the membrane filtration technique.

Place 10ml of the sample in a filtration device with a 0.45 micron membrane. Lay the membrane on a Tryptone Soy Agar plate and pre-incubate for 2-4 hours at 37°C or overnight at 20°C. Transfer the membrane onto the E. coli Direct AGAR MUG plate and incubate overnight at 44°C. Observe under Wood's lamp (366 nm) for the presence of fluorescent colonies. Lay a drop of Kovacs’ Reagent on the colonies. MUG positive and indole positive colonies are enumerated and identified as E.coli.

User quality assurance (37°C-24 hrs)

E.coli ATCC 25922: growth, fluorescent colonies under Wood’s lamp

C.freundii ATCC 43864: growth, not fluorescent colonies under Wood’s lamp

E.faecalis ATCC 19433: partially inhibited, no gas production

Dehydrated medium: 15-30°C