Carbon and Nitrogen Isotope Effects Associated with the Dioxygenation of Aniline and Diphenylamine

• Published in: Environmental science & technology 2012-11, Vol.46 (21), p.11844-11853
• Main Authors: Pati, Sarah G, Shin, Kwanghee, Skarpeli-Liati, Marita, Bolotin, Jakov, Eustis, Soren N, Spain, Jim C, Hofstetter, Thomas B
• Format: Article
• Language: English
• Subjects: Aniline Compounds - chemistry; Aniline Compounds - metabolism; Applied sciences; Biodegradation; Biodegradation, Environmental; Burkholderia - metabolism; Carbon Isotopes; Comparative analysis; Dioxygenases - metabolism; Diphenylamine - chemistry; Diphenylamine - metabolism; Earth sciences; Earth, ocean, space; Electrons; Engineering and environment geology. Geothermics; Exact sciences and technology; Global environmental pollution; Isotopes; Manganese Compounds - chemistry; Nitrogen Isotopes; Organic contaminants; Oxidation; Oxidation-Reduction; Oxides - chemistry; Pollutants; Pollution; Pollution, environment geology; Soil Pollutants - chemistry; Soil Pollutants - metabolism
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es303043t

Dioxygenation of aromatic rings is frequently the initial step of biodegradation of organic subsurface pollutants. This process can be tracked by compound-specific isotope analysis to assess the extent of contaminant transformation, but the corresponding isotope effects, especially for dioxygenation of N-substituted, aromatic contaminants, are not well understood. We investigated the C and N isotope fractionation associated with the biodegradation of aniline and diphenylamine using pure cultures of Burkholderia sp. strain JS667, which can biodegrade both compounds, each by a distinct dioxygenase enzyme. For diphenylamine, the C and N isotope enrichment was normal with εC- and εN-values of −0.6 ± 0.1‰ and −1.0 ± 0.1‰, respectively. In contrast, N isotopes of aniline were subject to substantial inverse fractionation (εN of +13 ± 0.5‰), whereas the εC-value was identical to that of diphenylamine. A comparison of the apparent kinetic isotope effects for aniline and diphenylamine dioxygenation with those from abiotic oxidation by manganese oxide (MnO2) suggest that the oxidation of a diarylamine system leads to distinct C–N bonding changes compared to aniline regardless of reaction mechanism and oxidant involved. Combined evaluation of the C and N isotope signatures of the contaminants reveals characteristic Δδ15N/Δδ13C-trends for the identification of diphenylamine and aniline oxidation in contaminated subsurfaces and for the distinction of aniline oxidation from its formation by microbial and/or abiotic reduction of nitrobenzene.