Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design



Committee Chair

Gary K. Bissonnette.


The examination of aquatic environments for bacterial indicator organisms has proven to be a useful and well-established practice for the purpose of monitoring microbiological water quality. An ideal indicator of fecal pollution should be present in sufficient density to allow detection, present simultaneous with pathogen(s), incapable of aftergrowth in external aquatic environments, easy to enumerate, and exclusively of fecal origin. Unfortunately, none of the indicator organisms presently in use today meet all of these requirements. Bifidobacteria show promise as indicators of fecal pollution in water with the additional ability of potentially distinguishing between fecal pollution of human and animal origin. In laboratory microcosm experiments, the survival of the bifidobacteria population was indirectly proportional to the temperature at which the microcosm was stored. In mixed microcosm studies with E. coli, the survival of the bifidobacteria population was considerably less than the E. coli population. The recovery of bifidobacteria from constructed wetlands receiving primary treated sewage was monitored using published selective media (YN6, BIM25, and BIM50 agar). In the influent and wetland samples, there was approximately a 2 to 3 log reduction of bifidobacteria, while fecal coliforms exhibited a 4 to 5 log reduction. Results indicate the YN6 medium lacks the desired sensitivity and selectivity to effectively enumerate bifidobacteria. Studies addressing the recovery of bifidobacteria from the wetlands with modified bifidobacteria enumeration media were mixed to unsuccessful.