Abstract
Toward the development of ecotoxicology methods to investigate microbial markers of impacts of hydrocarbon processing activities, DNA adductomic analyses were conducted on a sphingomonad soil bacterium. From growing cells that were exposed or unexposed to acrolein, a commonly used biocide in hydraulic fracturing processes, DNA was extracted, digested to 2′-deoxynucleosides and analyzed by liquid chromatography-positive ionization electrospray-tandem mass spectrometry in selected reaction monitoring mode transmitting the [M + H]+ > [M + H − 116]+ transition over 100 transitions. Overall data shown as DNA adductome maps revealed numerous putative DNA adducts under both conditions with some occurring specifically for each condition. Adductomic analyses of triplicate samples indicated that elevated levels of some targeted putative adducts occurred in exposed cells. Two exposure-specific adducts were identified in exposed cells as 3-(2′-deoxyribosyl)-5,6,7,8-tetrahydro-6-hydroxy-(and 8-hydroxy-)pyrimido[1,2-a]- purine-(3H)-one (6- and 8-hydroxy-PdG) following synthesis of authentic standards of these compounds and subsequent analyses. A time course experiment showed that 6- and 8-hydroxy-PdG were detected in bacterial DNA within 30 min of acrolein exposure but were not detected in unexposed cells. This work demonstrated the first application of DNA adductomics to examine DNA damage in a bacterium and sets a foundation for future work.
Highlights
DNA adductomics is an emerging field that was conceived of as a top down comprehensive nontargeted approach to detect DNA adducts in human tissues by utilizing liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS; Kanaly et al 2006, 2007; recently reviewed by Balbo et al 2014b)
Multiple DNA adductomics analyses were conducted on growing Sphingobium cells, with the following aims: (1) to evaluate potential differences in DNA damage depending upon exposure conditions, (2)
Sphingomonad bacteria survive and may thrive in soil environments that are contaminated with genotoxic hydrocarbon pollutants released at petroleum exploration and processing sites, including hydraulic fracturing sites which utilize acrolein as a biocidal agent
Summary
DNA adductomics is an emerging field that was conceived of as a top down comprehensive nontargeted approach to detect DNA adducts in human tissues by utilizing liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS; Kanaly et al 2006, 2007; recently reviewed by Balbo et al 2014b). The small molecule, acrolein, which is used in environmental applications where it is applied as a biocide in hydraulic fracturing processes and oilfield systems was chosen as a model toxicant (Hemminki et al.1980; Foiles et al 1989; Nordone et al 1996; Penkala et al 2004). In this investigation, multiple DNA adductomics analyses were conducted on growing Sphingobium cells, with the following aims: (1) to evaluate potential differences in DNA damage depending upon exposure conditions, (2). To unambiguously identify unknown adducts that may have occurred due to exposure to acrolein from complex data sets, and (3) to build a foundation upon which future prokaryotic DNA adductomics studies may be conducted
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