Compositional, genetic and functional characterization of soil culturable microbial communities in polychlorinated dibenzo-p-dioxins/furans contaminated soil

Abstract

Dioxins (PCDD/Fs) are one of the most toxic environmental pollutants known to date. Due to their structural stability and extreme hydrophobicity dioxins persist in the ecosystems and can be bioaccumulated to critical levels in both human and animal food chains. Soils are the most important reservoirs of dioxins, thus soil microbes are highly exposed to dioxins, impacting their diversity, genetics and functional characteristics. To experimentally evaluate these effects, the diversity and functionality of soil microbes were assessed in seven local sites potentially exposed to PCDD/Fs.Concentration of dioxins in soils samples was firstly determined and the soils cultivable microbes were identified and molecularly characterized as a function of their in vitro ability to degrade the TCDD. Our results revealed that the diversity of microbial communities largely varied among the sites and was likely inversely proportional to their level of contamination with PCDD/Fs. Furthermore, the genetics profiling of dioxin-degrading bacteria revealed that the Cytochrome P450 CYPBM3-positive species largely belong to the genus Bacillus and were randomly distributed among the soils samples, while the angular dioxygenase (AD)-positive species were mainly found in highly polluted soils with a major presence of the genus Pseudomonas. Finally, the functionality of dioxin-biodegrading genes (AD or CYPBM3), was confirmed by the ability of bacteria to consume 2,3,7,8-TCDD, and this was synchronized with an induced level of both pathways. Our results suggest that different dioxin-metabolizing pathways exist under the same environmental conditions and work differentially for an effective removal of PCDD/Fs.

Impact of dioxins on reproductive health in female mammals

“…The general chemical structures of PCDD and PCDFs consist of two benzene rings connected by one or two oxygen atoms and can contain four to eight chlorines ( Van den Berg et al, 2006 ). Due to their extreme lipophilicity, dioxins can bio accumulate by both plants and animals, causing thus several developmental abnormalities in ( Hanano et al, 2014a ; Hanano et al, 2014b ; Hanano et al, 2015 ; Hanano et al, 2018a ; Hanano et al, 2018b ; Hanano et al, 2018c ; Hanano et al, 2019 ; Mahfouz et al, 2020a ; Mahfouz et al, 2022 ). Terrestrial and aquatic environments are objected to dioxin contamination, subsequently elevated levels of dioxins can be accumulated in marine organisms and livestock.…”

Female‐to‐male differential transcription patterns of miRNA‐mRNA networks in the livers of dioxin‐exposed mice

“…[15][16][17] In term of toxicity, dioxins are known to cause irreversible biological damage in humans, animals, plants and microorganisms, leading to wider ecological, environmental and economic impacts. 10,11,[18][19][20][21][22][23][24][25][26][27][28][29][30][31] In mammals, the major toxicological effects of dioxins are mediated by the aryl hydrocarbon receptor (AhR), a member of the cytoplasmic receptors family that act as transcription factor. 32 In this fashion, the toxicity of dioxins is related to their affinity for AhR, with 2,3,7,8-TCDD being the most potent AhR agonist.…”

“…In term of toxicity, dioxins are known to cause irreversible biological damage in humans, animals, plants and microorganisms, leading to wider ecological, environmental and economic impacts 10,11,18–31 . In mammals, the major toxicological effects of dioxins are mediated by the aryl hydrocarbon receptor (AhR), a member of the cytoplasmic receptors family that act as transcription factor 32 .…”