TY - JOUR TI - Biotransformation of aniline, para-chloroaniline and pentachloronitrobenzene and environmental implications DO - https://doi.org/doi:10.7282/T3TH8K0S PY - 2014 AB - This dissertation describes research on biotransformation of aniline and para-chloroaniline (PCA) under anoxic and anaerobic conditions in sediments and groundwater aquifer solids recovered from a chemical industrial site. Four locations were examined: lightly and highly contaminated freshwater canal sediments, and lightly and highly contaminated aquifer sediments. Aquifer and canal microcosms showed loss of aniline under nitrate-, Fe (III)- and sulfate-amended conditons, and under methanogenic conditions. Expected intermediates of aniline biotransformation were not detected. Only 5 to 10 percent of 14C was recovered as CO2 from 14C-labelled aniline during a mineralization test. Thus, definitive pathways of biodegradation were not determined for aniline. PCA loss was observed in nitrate-amended microcosms. Reductive dechlorination of PCA was observed in canal microcosms under methanogenic conditions and was concurrent with stoichiometric aniline production. Dechlorination was slow, and was only observed after increasing the PCA concentration to 1500 µM and adding the electron donor/hydrogen source, lactate. PCA loss was not observed under methanogenic conditions in aquifer sediments. Combined with the observation of aniline loss in methanogenic microcosms, these results support the possibility for complete dechlorination of monochloroaniline to aniline and subsequent degradation of aniline in canal sediments. The bacterial phylotypes present in nitrate-aniline-amended microcosms clustered with known aniline degraders (Delftia) and nitrate-reducers (Acidovorax and Variovorax). The dominant phylotype in the most active aniline-amended transfers had high similarity to Magnetospirillum, a genus that is capable of nitrate reduction and degradation of aromatic pollutants. The phylotypes identified in PCA-dechlorinating microcosms included Dehalobacter, a dechlorinator that has been linked to dechlorination of chlorinated benzenes at the same site. This work highlights the potential for anaerobic transformation of aniline and PCA at this industrial site and is one of only a few studies that have identified bacterial community members in sediments and enrichments that carry out these transformations. More work is needed to conclusively identify the biological pathways responsible for the loss of aniline. Finally, a mixed culture containing Dehalococcoides mccartyi strain 195 was tested for ability to transform pentachloronitrobenzene to chlorinated anilines. The culture did not dechlorinate PCA. PCNB was abiotically transformed to pentachloroaniline, which was reductively dechlorinated to dichloroaniline. KW - Environmental Sciences KW - Aniline--Biodegradation KW - Chloroaniline--Biodegradation KW - Quintozene--Biodegradation KW - Biotransformation (Metabolism) LA - eng ER -