Membrane Filtration Test:

The Membrane Filtration method offers some advantages over other methods because it allows a much larger volume of water (for example, 100 mL) to be tested, and therefore it may detect lower levels of contamination.  It is also a quantitative test that determines the actual number of coliforms present per 100 mL volume. Water is filtered through a membrane of 0.45 mm porosity.  This membrane filter is then placed on a pad saturated with m-Endo MF broth, a selective and differential medium.  After a 24 hour incubation at 37˚C, colonies of coliforms, if present, will be dark pink/red and may exhibit a metallic sheen. 

Rachel Watson, M.S.
AG 5010
766-3524
Cell: 307-760-2942
rwatson@uwyo.edu