Method 1603: 'Escherichia coli' (E. coli) in Water by Membrane Filtration Using Modified membrane-Thermotolerant 'Escherichia coli' Agar (mTEC)

摘要

The method describes a revised Escherichia coli membrane filter (MF) procedure, a single-step method that uses one medium, modified mTEC Agar, and does not require the transfer of the membrane filter to another medium or other substrate. The modified medium contains a chromogen (5-bromo-6-chloro- 3-indolyl--D-glucuronide), which is catabolized to glucuronic acid and a red- or magenta-colored compound byE. coli that produce the enzyme D-glucuronidase. The apparatus and equipment, and sampling, filtration, and verification procedures for this modified mTEC method are identical to those of the original mTEC method. Because the bacterium is a natural inhabitant only of the intestinal tract of warm-blooded animals, its presence in water samples is an indication of fecal pollution and the possible presence of entericpathogens.