Explain Procedure for the test of Presence of Coliform Bacteria?

This test procedure is in continuation to the presumptive test procedure followed on last experiment. Now carry out this exercise following the steps enumerated herewith.

1. Label the EMB/Endo agar plates with the source of the water sample.

2. Streak the plates with the respective positive or doubtful presumptive broth culture using sterile inoculating loop.

3. Incubate all the culture plates in an inverted position for 24 hours at 37°C.

4. Observe the plates for the presence or absence of E.coli colonies.

Appearance of typical colonies with dark centres and metallic sheen indicates positive confirmed test, i.e., water is non potable.