title: Polycyclic aromatic hydrocarbon-contaminated soils: bioaugmentation of autochthonous bacteria and toxicological assessment of the bioremediation process by means of Vicia faba L.
abstract: Two bacterial strains, Achromobacter sp. (ACH01) and Sphingomonas sp. (SPH01), were isolated from a heavily polycyclic aromatic hydrocarbon (PAH)-contaminated soil (5431.3 ± 102.3 ppm) for their capacity to use a mixture of anthracene, pyrene, phenanthrene and fluorene as sole carbon sources for growth and for the capacity to produce biosurfactants. The two strains were exploited for bioaugmentation in a biopile pilot plant to increase the bioavailability and the degradation of the residual PAH contamination (99.5 ± 7.1 ppm) reached after 9 months of treatment. The denaturing gel gradient electrophoresis (DGGE) profile of the microbial ecology of the soil during the experimentation showed that the bioaugmentation approach was successful in terms of permanence of the two strains in the soil in treatment. The bioaugmentation of the two bacterial isolates positively correlated with the PAH depletion that reached 7.9 ± 2 ppm value in 2 months of treatment. The PAH depletion was assessed by the loss of the phyto-genotoxicity of soil elutriates on the model plant Vicia faba L., toxicological assessment adopted also to determine the minimum length of the decontamination process for obtaining both the depletion of the PAH contamination and the detoxification of the soil at the end of the process. The intermediate phases of the bioremediation process were the most significant in terms of toxicity, inducing genotoxic effects and selective DNA fragmentation in the stem cell niche of the root tip. The selective DNA fragmentation can be related to the selective induction of cell death of mutant stem cells that can compromise offsprings.
authors.affiliation: Department of Biology, University of Pisa, via Ghini 13, 56126, Pisa, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Ruffini Castiglione
authors.affiliation: National Research Council (CNR), Institute of Biology and Agricultural Biotechnology (IBBA), Research Unit of Pisa, Via Moruzzi 1, 56124, Pisa, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Giorgetti
authors.affiliation: Department of Biology, University of Pisa, via Ghini 13, 56126, Pisa, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Becarelli
authors.affiliation: Department of Biology, University of Pisa, via Ghini 13, 56126, Pisa, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Siracusa
authors.affiliation: Department of Biology, University of Pisa, via Ghini 13, 56126, Pisa, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Lorenzi
authors.affiliation: Department of Biology, University of Pisa, via Ghini 13, 56126, Pisa, Italy. sdigregorio@biologia.unipi.it.
authors.forename: Simona
authors.initials: S
authors.lastname: Di Gregorio
mesh_terms: D042402:Achromobacter / Q000302:isolation & purification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D010865:Pilot Projects; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis* / Q000633:toxicity; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000633:toxicity; D020578:Sphingomonas / Q000302:isolation & purification / Q000378:metabolism*; D031307:Vicia faba / Q000187:drug effects* / Q000254:growth & development
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants
keywords: Achromobacter sp.; Bioaugmentation; Biosurfactants; Genotoxicity; Phytotoxicity; Polycyclic aromatic hydrocarbons; Sphingomonas sp.; Vicia faba L.