Detecting E. coli in Water: A Guide to the Membrane Filter Technique
Detecting E. coli Using Membrane Filter Technique In the laboratory, E. coli can be detected using the membrane filter technique, a common method for water quality analysis. Here's how it's done: Sample Collection : Collect a water sample from the source to be tested. Filtration : Pass the water sample through a membrane filter with a pore size small enough to trap bacteria. Typically, filters with a pore size of 0.45 micrometers are used. Incubation : Place the membrane filter on a nutrient agar medium specifically designed for E. coli growth. Incubate the agar plates at a suitable temperature (usually 35-37°C) for 24 hours. Colonies Observation : After incubation, examine the agar plates for the presence of characteristic E. coli colonies. E. coli colonies typically appear as small, pinkish-red colonies with a metallic sheen on Eosin Methylene Blue (EMB) agar. Confirmation : Perform additional biochemical tests (e.g., Indole test, Methyl Red test) to confirm the presence of...