title: Bioaugmentation of a historically contaminated soil by polychlorinated biphenyls with Lentinus tigrinus.
abstract: BACKGROUND
  Several species belonging to the ecological group of white-rot basidiomycetes are able to bring about the remediation of matrices contaminated by a large variety of anthropic organic pollutants. Among them, polychlorobiphenyls (PCBs) are characterized by a high recalcitrance due to both their low bioavailability and the inability of natural microbial communities to degrade them at significant rates and extents. Objective of this study was to assess the impact of a maize stalk-immobilized Lentinus tigrinus CBS 577.79 inoculant combined with soybean oil (SO), as a possible PCB-mobilizing agent, on the bioremediation and resident microbiota of an actual Aroclor 1260 historically contaminated soil under unsaturated solid-phase conditions.
  
  
  RESULTS
  Best overall PCB depletions (33.6 ± 0.3%) and dechlorination (23.2 ± 1.3%) were found after 60 d incubation in the absence of SO where, however, the fungus appeared to exert adverse effects on both the growth of biphenyl- and chlorobenzoate-degrading bacteria and the abundance of genes coding for both biphenyl dioxygenase (bph) and catechol-2,3-dioxygenase. A significant (P < 0.001) linear inverse relationship between depletion yields and degree of chlorination was observed in both augmented and control microcosms in the absence of SO; conversely, this negative correlation was not evident in SO-amended microcosms where the additive inhibited the biodegradation of low chlorinated congeners. The presence of SO, in fact, resulted in lower abundances of both biphenyl-degrading bacteria and bph.
  
  
  CONCLUSIONS
  The PCB depletion extents obtained in the presence of L. tigrinus are by far higher than those reported in other remediation studies conducted under unsaturated solid phase conditions on actual site soils historically contaminated by Aroclor 1260. These results suggest that the bioaugmentation strategy with the maize stalk-immobilized mycelium of this species might be promising in the reclamation of PCB-contaminated soils. The addition of SO to matrices contaminated by technical PCB mixtures, such as Aroclor 1242 and Delor 103 and characterized by a large preponderance of low chlorinated congeners, might not be advisable.
authors.affiliation: Department of Cellular and Environmental Biology, University of Perugia, Perugia, Italy.
authors.forename: Ermanno
authors.initials: E
authors.lastname: Federici
authors.forename: Mariangela
authors.initials: M
authors.lastname: Giubilei
authors.forename: Guglielmo
authors.initials: G
authors.lastname: Santi
authors.forename: Giulio
authors.initials: G
authors.lastname: Zanaroli
authors.forename: Andrea
authors.initials: A
authors.lastname: Negroni
authors.forename: Fabio
authors.initials: F
authors.lastname: Fava
authors.forename: Maurizio
authors.initials: M
authors.lastname: Petruccioli
authors.forename: Alessandro
authors.initials: A
authors.lastname: D'Annibale
mesh_terms: D001673:Biodegradation, Environmental; D050557:Catechol 2,3-Dioxygenase / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D020074:Lentinula / Q000201:enzymology*; D010105:Oxygenases / Q000378:metabolism; D011078:Polychlorinated Biphenyls / Q000737:chemistry / Q000378:metabolism*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism*; D013024:Soybean Oil / Q000737:chemistry / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D007506:Iron-Sulfur Proteins; D012989:Soil Pollutants; D013024:Soybean Oil; D011078:Polychlorinated Biphenyls; D010105:Oxygenases; D050557:Catechol 2,3-Dioxygenase; C074161:biphenyl-2,3-dioxygenase