Text

theses

ETD doctoral

This dissertation describes studies of biodegradation of two groups of aromatic compounds which are major contaminants of concern at contaminated sites in New Jersey. Chlorinated dibenzo-p-dioxins pollute the Passaic River in the north, and aniline and para-chloroaniline (PCA) pollute a chemical manufacturing site in the south. All the chemical compounds in this study are harmful to living organisms and the environment. They are carcinogenic to humans. Sediments from the Passaic River were enriched with dibenzofuran (DF) (as an analog for dibenzo-p-dioxin) and three bacterial strains, Janibacter sp.PR1, Agromyces sp. PR2, and Arthrobacter sp. PR3, were isolated. The strains could use DF as a carbon and energy source. Agromyces sp.PR2 and Arthrobacter sp. PR3 were further examined and found to transform dibenzo-p-dioxin (DD) and 2-monochlorodibenzo-p-dioxin (2MCDD), but neither of them could transform 2,7-dichlorodibenzo-p-dioxin (2,7DCDD), even after prolonged incubation. Functional gene characterization was performed for all three strains. Janibacter sp. PR1 and Agromyces sp. PR2 had identical angular dioxygenases which are closely related to previously characterized angular dioxygenases. We were unable to identify an angular dioxygenase from Arthrobacter sp. PR3. Isolation of native bacterial strains which degrade contaminants is an essential step needed for consideration in any future bioremediation technology of the site.

Biodegradation of aniline and PCA under different redox conditions was examined in aquifers underlying a chemical manufacturing site. A detailed set of site data was established by collaborators. The data were evaluated with respect to the sediment geochemistry, groundwater contaminant concentrations, and electron acceptor presence, then sediments from different depths were selected to establish specific microcosm tests. In the case of targeted microcosms, soils from specific depths were used, while for composited microcosms, soils from combined depths were used. Contaminants of concern, aniline and/or PCA were added as carbon sources. Targeted microcosms showed no substantial loss in aniline and PCA concentrations. Composited microcosms showed loss in aniline and PCA concentrations, especially under aerobic and sulfate-reducing redox conditions. The aniline and PCA concentrations were depleted several times after reamendment. Bacterial community analysis showed a shift in the bacterial community of the aerobic microcosms presumably reflecting growth on aniline. A pure isolate was obtained from the aerobic culture which could use aniline as a carbon and nitrogen source. The strain, along with another aniline degrading strain isolated from the Passaic River site, were used together to bioaugment one bottle of an inactive targeted microcosm set. Aniline was depleted quickly after addition of the cells, indicating active biomass is missing in the targeted microcosms. Stable isotope probing (SIP) of active aerobic microcosms showed there was an incorporation of 13C aniline. Analysis of the DNA fractions from the SIP experiment showed that a phylotype related to Knoellia dominated two of the microcosms, while phylotypes related to Aquabacterium and Brevundimonas also appeared to be important in aniline degradation. The outputs of the project are identification of biodegradation processes and specific active organisms at the two sites. These findings are important and useful for eventual application of bioremediation technologies at the sites.

ETD_11204

Ph.D.

Includes bibliographical references

doi:10.7282/t3-mh2p-c930

The author owns the copyright to this work.