A bacterial bioreporter panel to assay the cytotoxicity of atmospheric particulate matter Nivi Kessler a, b, * , James J. Schauer c , Sharon Yagur-Kroll a , Sahar Melamed a ,Ofir Tirosh b , Shimshon Belkin a , Yigal Erel b a Institute of Life Sciences, The Hebrew University of Jerusalem, Israel b Institute of Earth Sciences, The Hebrew University of Jerusalem, Israel c Civil and Environmental Engineering, University of WisconsineMadison, USA highlights < A new bacterial bioassay for toxicity of particulate air pollution is presented. < Bioassay responses indicating toxicity were observed for several PM samples. < These responses suggest oxidative stress, respiration inhibition and Fe deficiency. < A metal chelating treatment of the samples relieved the bioassay’s responses. < Bioavailability analysis suggested that Cr was related to these toxic responses. article info Article history: Received 11 December 2011 Received in revised form 10 September 2012 Accepted 12 September 2012 Keywords: Toxicity Particles Air pollution Biosensors Metals Oxidative stress abstract Numerous studies have demonstrated that elevated concentrations of suspended atmospheric particu- late matter (PM) are associated with adverse health effects. In order to minimize the adverse public health effects of atmospheric PM by exposure management, there is a need for a greater understanding of the toxic mechanisms and the components that are responsible for the toxic effects. The aim of this study was to utilize bioassay techniques to investigate these aspects. For this purpose a reporter panel of 9 genetically engineered bacterial (Escherichia coli) strains was composed. Each panel member was designed to report on a different stress condition with a measurable light signal produced by the luciferase enzyme. Toxic mechanisms and components were studied using six anthropogenic PM source samples, including two vehicle combustion particles, three coal fly ash (CFA) samples and an urban dust sample. The most prominent outcome of the panel exposure results were broad panel responses observed for two of the CFA samples, indicating oxidative stress, respiration inhibition and iron deficiency. These responses were relieved when the samples were treated with EDTA, a non-specific metal chelator, suggesting the involvement of metals in the observed effects. Bioavailability analysis of the samples suggests that chromium was related to the toxic responses induced by two of the CFA samples. Oxidative stress was also observed in several samples of ambient atmospheric aerosols and excess metal toxicity in an urban dust sample collected in a parking lot. The reporter panel approach, as demonstrated in this study, has the potential of providing novel insights as to the mechanisms of atmospheric PM toxicity. Furthermore, combining the panel’s results with bioavailability data can enlighten about the role of different PM components in the observed toxicity. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Epidemiological studies over the past few decades have consistently demonstrated the adverse effects of outdoor air pollution on human health, and in particular the harmful impact of high ambient concentrations of fine particles. The landmark Six * Corresponding author. Institute of Life Sciences, The Hebrew University of Jer- usalem, Jerusalem, Israel. E-mail address: nivikes@gmail.com (N. Kessler). Contents lists available at SciVerse ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv 1352-2310/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.atmosenv.2012.09.048 Atmospheric Environment 63 (2012) 94e101