AWWA QTC97033

In 1989, the US Environmental Protection Agency approved the Colilert methodology and, in 1994, the Colisure methodology for the detection of total coliform in drinking water. Both methods detect total coliform bacteria by testing for the presence of the enzyme beta-D-galactosidase. One of the possible problems with these tests is interference from non-coliform bacteria, such as Aeromonas and Pseudomonas, that produce small amounts of the same enzyme. Both Colilert and Colisure contain a suppressing agent for the non-coliform organisms, and will not produce a false positive result unless the concentration of these organisms is more than 10,000 colony-forming units per mL. The purpose of this study was to determine the suppression levels of Colilert, Colilert-18 and Colisure using wild strains of Aeromonas isolated from Colilert positive samples. Suppression level is defined as the largest number of Aeromonas that can be inoculated into a test without producing a positive test. Once the suppression level for each method was determined, mixed levels of Aeromonas hydrophila and Enterobacter cloacae were inoculated to determine if it was possible to identify E. cloacae in mixed cultures in Colilert, Colisure and Colilert-18.

Product Details

Published:

01/01/1997

ISBN(s):

0898679583

Number of Pages:

7

File Size:

1 file , 31 KB