Traceability of polychlorinated dibenzo-dioxins/furans pollutants in soil and their ecotoxicological effects on genetics, functions and composition of bacterial community Abdulsamie Hanano ⇑ , Hassan Ammouneh, Ibrahem Almousally, Abdulfattah Alorr, Mouhnad Shaban, Amer Abu Alnaser, Iyad Ghanem Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), B.P. Box 6091, Damascus, Syria highlights  Dioxin-pollution is estimated near potential industrial dioxins sources.  The highest dioxin-pollution is detected in the vicinity of petroleum refineries.  Soil microbial diversity and functionality is affected by dioxin-pollution.  Transcript of AD a-subunit is abundant in the heavily dioxin-polluted soil.  No relationship is observed between CYPBM3 expression and dioxin level in soil. article info Article history: Received 10 December 2013 Received in revised form 23 January 2014 Accepted 26 January 2014 Available online xxxx Keywords: Polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) Soil bacterial community Biodiversity Angular dioxygenase (AD) Cytochrome P450 (CYPBM3) Biodegradation abstract Dioxins (PCDD/Fs) are persistent organic pollutants. Their accumulation in soil is a crucial step in their transmission through the ecosystem. Traceability of dioxin in soil was evaluated in four sites A, B, C and D considered as potential industrial PCDD/Fs sources in Syria. Our results showed that the highest pollu- tion with dioxin (P50 ppt) was found in site C (vicinity of Homs refinery). In parallel, analysis of physico- chemical proprieties and bacterial density of soil samples were carried out. Bacterial density differed significantly among samples between 68  10 4 and 64  10 6 CFU g 1 DW. Analysis of 16S rRNA encoding sequences showed that the genus Bacillus was the most abundant (74.7%) in all samples, followed by the genera Arthrobacter and Klebsiella with 5.2% and 4.7%, respectively. The genera Microbacterium, Pantoea, Pseudomonas, Enterobacter and Exiguobacterium formed between 2.1% and 2.6%. Cellulomonas, Kocuria, Lysinibacillus, Staphylococcus and Streptomyces were in a minority (0.5–1%). The bacterial richness and biodiversity, estimated by D Mg and H 0 index, were highest in the heavily polluted site. Molecular screening for angular dioxygenase (AD a-subunit) and the cytochrome P450 (CYPBM3) genes, led to identification of 41 strains as AD-positive and 31 strains as CYPBM3-positive. RT-real-time PCR analysis showed a signif- icant abundance of AD a-subunit transcript in the heavily dioxin-polluted soils, while the expression of CYPBM3 was highest in the moderately polluted soils. Our results illustrate the microbial diversity and functionality in soil exposed to dioxin pollution. Identification of dioxin-degrading bacteria from polluted sites should allow bioremediation to be carried out. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzodioxins (PCDDs), collectively termed ‘‘dioxins’’ are persistent organic pollutants (POPs) covered by the Stockholm Convention. Depending on chlorination level (P = 1–8), dioxins form a generic group of 75 PCDD congeners and 135 PCDF congen- ers with varying degrees of toxicity. Congeners with chlorine atoms substituted in the lateral 2, 3, 7 and 8 positions of the aro- matic rings are, however, considered as the most toxic. Toxicity is expressed in Toxicological Equivalence or TEQ units. Of these, 2,3,7,8-TCDD is considered the most toxic and the remaining cong- eners have their toxicity compared to 2,3,7,8-TCDD using toxic http://dx.doi.org/10.1016/j.chemosphere.2014.01.061 0045-6535/Ó 2014 Elsevier Ltd. All rights reserved. Abbreviations: TCDD, 2,3,7,8-polychlorinated dibenzo-p-dioxins; D Mg , Marga- lef’s index; H 0 , Shannon–Wiener index; AD, angular dioxygenase; CYPBM3, B. megaterium cytochrome P450; RT-QPCR, real-time quantitative PCR. ⇑ Corresponding author. Tel.: +963 11 2132580; fax: +963 11 6112289. E-mail address: ashanano@aec.org.sy (A. Hanano). Chemosphere xxx (2014) xxx–xxx Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere Please cite this article in press as: Hanano, A., et al. Traceability of polychlorinated dibenzo-dioxins/furans pollutants in soil and their ecotoxicological ef- fects on genetics, functions and composition of bacterial community. Chemosphere (2014), http://dx.doi.org/10.1016/j.chemosphere.2014.01.061