Date of Award


Degree Name

Master of Science


Biological Sciences

First Advisor

Dr. Silvia Rossbach

Second Advisor

Dr. John Quensen

Third Advisor

Dr. Karim Essani

Fourth Advisor

Dr. Charles Ide

Access Setting

Masters Thesis-Open Access


The Kalamazoo River is contaminated with polychlorinated biphenyls (PCBs) which are neurotoxins and suspected carcinogens. The goal of this study was to isolate, identify, and metabolically characterize PCB degrading strains of aerobic bacteria. Biphenyl enrichments resulted in the isolation of putative PCB degrading strains from different locations along the river. Based on 16S rRNA gene analysis the isolated strains were identified as belonging to the genera of Achromobacter, Acidovorax, Cellulosimicrobium, Paenibacillus, Pseudomonas, and Rhodococcus. These strains were screened for their PCB degrading ability and congener specificity. All of the isolated strains degraded PCBs via the 2,3-dioxygenase pathway. The range of PCBs degraded was limited to mono- to tri-substituted congeners. In addition, the isolated strains oxidized 2,4'-CB but accumulated problematic intermediate metabolites. These results indicate that most of the aerobic-PCB-degrading bacteria isolated in this study from the Kalamazoo River have a moderate potential to degrade the lesser chlorinated PCBs, while one strain (D1) was found to have above average PCB degrading capabilities.

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