Easy Dry^TM are absorbent pads saturated with a sterile, dehydrated culture medium. Each pad is pre-plated in a Petri dish and is immediately ready to use after pouring sterile distilled or deionized water on it. Easy DryTM are optimal for the examination of large sample volumes by the membrane filter method.

Easy Dry^TM Tergitol is a selective isolation medium used for the detection and enumeration of Escherichia coli and coliform bacteria in water, based on lactose fermentation.

Tergitol TTC agar (the corresponding agar medium which contains triphenyltetrazolium chloride as well) is described in ISO 9308-1:2000.

PREPARATION

1.   Cut open a bag and remove the number of Easy Dry plates needed.

2.   Moisten the pad contained in the Petri dish with 2.2 ml of sterile distilled or deionized water.

3.   Wait 5 minutes before using.

TEST PROCEDURE

Filter the sample through a filter membrane (0.45 µm pore diameter). Transfer the membrane onto a plate containing a just rehydrated pad. Incubate aerobically at 36 ± 2°C for 18-24 hours.

NOTES

If necessary, the incubation may be extended for up to 48 hours.

To limit the secondary flora while promoting growth of E. coli, it is possible to incubate another plate at 44°C.

INTERPRETING RESULTS

Examine the membrane for growth and acidification of the medium (yellow) under the membrane:

• Colonies of E. coli and other lactose-fermenting organisms such as Enterobacter and Klebsiella show a yellow halo in the corresponding medium;

• Non-lactose fermenting organisms (e.g. Salmonella, Shigella, Proteus, Pseudomonas) show a green-blue color in the medium.

For confirmation, subculture selected colonies onto a non-selective agar and perform oxidase test and indole test. All coliform bacteria are oxidase-negative. Colonies that are oxidase-negative but indole-positive are counted as Escherichia coli.

APPEARANCE OF THE MEDIUM

Whitish pad. Pale green once rehydrated.

STORAGE

Store at 10-25°C away from light. Do not use the product beyond its expiry date on the label or if product shows any evidence of contamination or any sign of deterioration.

SHELF LIFE

2 years.