Step-by-step Procedures of Membrane Filtration technique:

Collect the sample and make any necessary dilutions.
Select the appropriate nutrient or culture medium. Dispense the broth into a sterile Petri dish, evenly saturating the absorbent pad.
Flame the forceps, and remove the membrane from the sterile package.
Place the membrane filter into the funnel assembly.
Flame the pouring lip of the sample container and pour the sample into the funnel.
Turn on the vacuum and allow the sample to draw completely through the filter.
Rinse funnel with sterile buffered water. Turn on the vacuum and allow the liquid to draw completely through the filter.
Flame the forceps and remove the membrane filter from the funnel.
Place the membrane filter into the prepared Petri dish.
Incubate at the proper temperature and for the appropriate time period.
Count and confirm the colonies and report the results.
Advantage of Membrane Filter Technique

Permits testing of large sample volumes. Theoretically, almost any volumes of non-turbid water could be filtered through the disk, the organisms from any given volume being deposited in the disk.
The membrane can be transferred from one medium to another for purposes of selection or differentiation of organisms thus allowing isolation and enumeration of discrete colonies of bacteria.
Results can be obtained more rapidly than by the conventional MPN standard methods. It provides presence or absence information within 24 hours.
Uses of Memberane filters

Membrane filters are used extensively in the laboratory and in the industry to sterilize heat-labile fluid materials.
Effective and acceptable technique to monitor drinking water.
Useful for bacterial monitoring in the pharmaceutical, cosmetics, electronics, and food and beverage industries.
Allows for removal of bacteriostatic or bactericidal agents that would not be removed in pour plate, spread plate, or MPN techniques.

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