Dataset Information

Diversity and Abundance of High-Molecular-Weight Azaarenes in PAH-Contaminated Environmental Samples.

ABSTRACT: Azaarenes are N-heterocyclic polyaromatic pollutants that co-occur with polycyclic aromatic hydrocarbons (PAHs) in contaminated soils. Despite the known toxicity of some high-molecular-weight azaarenes, their diversity, abundance, and fate in contaminated soils remain to be elucidated. We applied high-resolution mass spectrometry and mass-defect filtering to four PAH-contaminated samples from geographically distant sites and detected 232 azaarene congeners distributed in eight homologous series, including alkylated derivatives and two hitherto unknown series. Four- and five-ring azaarenes were detected among these series, and the most abundant nonalkylated congeners groups (C13H9N, C15H9N, C17H11N, C19H11N, and C21H13N) were quantified. The profiles of congener groups varied among different sites. Three-ring azaarenes presented higher concentrations in unweathered sites, while four- and five-ring azaarenes predominated in weathered sites. Known toxic and carcinogenic azaarenes, such as benzo[c]acridine and dibenzo[a,h]acridine, were detected along with their multiple isomers. Our results highlight a previously unrecognized diversity and abundance of azaarenes in PAH-contaminated sites, with corresponding implications for environmental monitoring and risk assessment.

SUBMITTER: Tian Z

PROVIDER: S-EPMC6343503 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Diversity and Abundance of High-Molecular-Weight Azaarenes in PAH-Contaminated Environmental Samples.

Tian Zhenyu Z Vila Joaquim J Wang Hanyan H Bodnar Wanda W Aitken Michael D MD

Environmental science & technology 20171201 24

Azaarenes are N-heterocyclic polyaromatic pollutants that co-occur with polycyclic aromatic hydrocarbons (PAHs) in contaminated soils. Despite the known toxicity of some high-molecular-weight azaarenes, their diversity, abundance, and fate in contaminated soils remain to be elucidated. We applied high-resolution mass spectrometry and mass-defect filtering to four PAH-contaminated samples from geographically distant sites and detected 232 azaarene congeners distributed in eight homologous series, ...[more]

PMID: 29160699

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Project description:It has recently been suggested that oxygenic dismutation of NO into N2 and O2 may occur in the anaerobic methanotrophic "Candidatus Methylomirabilis oxyfera" and the alkane-oxidizing gammaproteobacterium HdN1. It may represent a new pathway in microbial nitrogen cycling catalyzed by a putative NO dismutase (Nod). The formed O2 enables microbes to employ aerobic catabolic pathways in anoxic habitats, suggesting an ecophysiological niche space of substantial appeal for bioremediation and water treatment. However, it is still unknown whether this physiology is limited to "Ca Methylomirabilis oxyfera" and HdN1 and whether it can be coupled to the oxidation of electron donors other than alkanes. Here, we report insights into an unexpected diversity and remarkable abundance of nod genes in natural and engineered water systems. Phylogenetically diverse nod genes were recovered from a range of contaminated aquifers and N-removing wastewater treatment systems. Together with nod genes from "Ca Methylomirabilis oxyfera" and HdN1, the novel environmental nod sequences formed no fewer than 6 well-supported phylogenetic clusters, clearly distinct from canonical NO reductase (quinol-dependent NO reductase [qNor] and cytochrome c-dependent NO reductase [cNor]) genes. The abundance of nod genes in the investigated samples ranged from 1.6 × 107 to 5.2 × 1010 copies · g-1 (wet weight) of sediment or sludge biomass, accounting for up to 10% of total bacterial 16S rRNA gene counts. In essence, NO dismutation could be a much more widespread physiology than currently perceived. Understanding the controls of this emergent microbial capacity could offer new routes for nitrogen elimination or pollutant remediation in natural and engineered water systems. NO dismutation into N2 and O2 is a novel process catalyzed by putative NO dismutase (Nod). To date, only two bacteria, the anaerobic methane-oxidizing bacterium "Ca Methylomirabilis oxyfera" and the alkane-oxidizing gammaproteobacterium HdN1, are known to harbor nod genes. In this study, we report efficient molecular tools that can detect and quantify a wide diversity of nod genes in environmental samples. A surprisingly high diversity and abundance of nod genes were found in contaminated aquifers as well as wastewater treatment systems. This evidence indicates that NO dismutation may be a much more widespread physiology in natural and man-made environments than currently perceived. The molecular tools presented here will facilitate further studies on these enigmatic microbes in the future.

Dataset Information

Diversity and Abundance of High-Molecular-Weight Azaarenes in PAH-Contaminated Environmental Samples.

Publications

Diversity and Abundance of High-Molecular-Weight Azaarenes in PAH-Contaminated Environmental Samples.

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