This method can be done in the field or laboratory. Agar plates are incubated at 44.5 C for 22-24 hours . The mFC agar contains selective and differential agents. Rosolic acid inhibits bacterial growth in general, except for fecal coliforms.
Bile salts inhibit non-enteric bacteria.
Aniline blue indicates the ability of fecal coliforms to ferment lactose to acid that causes a pH change in the medium. The mFC method can be used for monitoring all types of waters. Because fecal coliforms may be from nonfecal sources, however, we recommend the mFC method be used in new monitoring programs for comparisons with historical data only. Instead, for new studies, E. coli should routinely be tested. E. coli is natural inhabitant of the gastrointestinal tract of warm-blooded animals and is direct evidence of fecal contamination.