Membrane Filter 47mm-Cellulose Nitrate 0,45um with Grid Sterile Ind Wrapped 100

The MF test is easier to perform than the MPN test because it requires fewer test tubes and less handling. Usually about 100 ml of water is passed through a membrane filter (pore size 0.45 µm). This membrane is then placed on a thin, absorbent pad saturated with differential or selective medium (Figure 17.2). For example, if total coliform organisms are sought, a modified Endo medium is used. For coliform bacteria, the filter is incubated at 35 ° C for 18 to 24 hours. The success of the method depends on using the correct media to facilitate identification of the bacterial colonies growing on the membrane filter surface. To continue with the previous example, enumerating colonies that have a green sheen indicates the number of coliform bacteria in a water sample.

C.P. GERBA, I.L. PEPPER, in Environmental Monitoring and Characterization, 2004

FIGURE 17.2. Membrane filtration for determining the coliform count in a water sample, using vacuum filtration (From Pollution Science © 1996, Academic Press, San Diego.)

Selection of appropriate nutrient medium: For the isolation and enumeration of different pathogenic microorganisms in water, we can use a variety of nutrient medium.