Part of the Wastewater and Pollution Control Series

designed for wastewater laboratory analysts.

by

Scott J. Bradley B. A. Aquacheck Laboratory, Inc.

1-800-263-9596 Aquacheck Laboratory, Inc.

EPA Selects Modified m-TEC as an approved E. coli method for NPDES reporting.

In 1981, A.P. Dufour was credited with developing the membrane filtration technique for the enumeration and identification of E. coli, called m-TEC.

1

m-TEC stands for: membrane thermotolerant E. coli.

In 1986, the EPA recommended that E. coli be used as the main bacterial water quality indicator used to monitor the safety of ambient and recreational waters with respect to gastroenteritis and other in-kind maladies.2

In March of 2007, the EPA approved Modified m-TEC, method EPA 1603, over regular m-TEC for NPDES reporting.

1Applied Environmental Microbiology – May, 1981 vol. 41 nos. 1152-11581Applied Environmental Microbiology – May, 1981 vol. 41 nos. 1152-1158

Wastewater Microbiology: E. coliWastewater Treatment facilities that monitor E. coli

as well as fecal Coliform bacteria, often have to contend with rapidly changing environments with respect to the influent and effluent matrices.

pH changes, oxygen imbalances, varying food sources, temperatures, harsh chemicals, and other factors may affect the bacterial equilibrium in a wastewater facility.

It is important to use a media that can revive and encourage E. coli growth, while discouraging competing organisms.

Modified m-TEC developed by the USEPA for the enumeration of E. coli

The USEPA developed Modified m-TEC as a means of enumerating E. coli in a variety of environments including ambient waters as well as wastewater.

Modified m-TEC removes the urea substrate step needed by regular m-TEC, which saves time and materials.

Also, pads to soak the urea substrate are needed as an extra item required for regular m-TEC.

Modified m-TEC’s Special ChemistryIt is the special proprietary chromogen that makes

modified m-TEC the method of choice.5-Bromo-6-Chloro-3-Indolyl-ß-D-Glucuronide is the

chemical name for the chromogen found in Modified m-TEC. It makes any E. coli colonies present in the sample turn a bright red-magenta color.

This makes Modified m-TEC a much easier method for identifying E. coli colonies on a prepared agar plate.

Plus, it is a one-step procedure – no urea substrate!

Wastewater E. coli with Modified m-TECEscherichia coli in wastewater effluents don’t have a chance to hide any more! See the difference between E. coli with

regular m-TEC as compared to Modified m-TEC. Which prepared media plate would you

rather count? E. coli on Modified m-TEC3 E. coli on

regular m-TEC4

Photo courtesy Aquacheck Laboratory, Inc.

Photo courtesy of Difco Co.

The Modified m-TEC Difference!Wastewater laboratory analysts would be

doing themselves a favor by trying EPA Method 1603: Modified m-TEC.

Cleaner colony morphology, greater selectivity, and…

You gotta love those big, bright, red-magenta colonies!

Wastewater Microbiology We hope you have enjoyed this presentation for

wastewater laboratory analysts:“Modified m-TEC over regular m-TEC for better selectivity, identification and enumeration of E.

coli.”

Brought to you as a courtesy from:Scott J. Bradley B.A. – Aquacheck Laboratory, Inc.

1-800-263-9596 www.Aquacheck-VT.com