Final answer:
The presumptive determination of coliforms uses lactose broth tubes where a red to yellow color change indicates their presence. Confirmed determination involves selective and differential media as well as further biochemical tests.
Step-by-step explanation:
The media used for the presumptive determination of coliforms includes lactose broth tubes containing a pH indicator that changes color in the presence of coliform bacteria due to lactose fermentation. When the medium changes from red to yellow, this indicates the presence of coliforms. This is a presumptive test, which suggests the presence of coliforms, but confirmatory tests are needed to be certain.
For confirmed determination of coliforms, additional tests, such as those on selective and differential media, are necessary. These tests can identify specific bacterial pathogens by observing the growth and appearance of bacterial colonies and certain biochemical reactions, such as a color change characteristic for a particular pathogen. Definitive identification may require further testing beyond the phenotypic level, like DNA analysis, for the final confirmation of the bacteria's identity.