Screening of ligninolytic fungi potentially useful for bioremediation of creosote-treated wood sleepers

Abstract

Creosote is a complex mixture of several hundreds chemicals obtained from distillation of hard coal tar mainly composed by aromatic hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs (which can constitute up to 90% of creosote), phenolics, oxygen-, nitrogen- and sulfur-containing heterocycles including dibenzofurans, aromatic amines, and it is widely used for wood treatment due to its efficient preservative properties as biocide. The aim of this research is to study the potential of selected basidiomycetes and ascomycetes, in particular white-rot fungi for the bioremediation of creosote in expended wood crossties. Fungal species, previously selected for their resistance to different pollutant concentrations, have been further investigated to determine their ability to produce ligninolytic enzymes, such as laccase (E.C. 1.10.3.2), manganese dependent peroxidase (E.C. 1.11.1.13), lignin peroxidase (E.C. 1.11.1.13), as a parameter to assess their potential for bioremediation. Dual co-culture consortia were also investigated to evaluate the possibility of improving the mycoremediation effectiveness. Composition of creosote in railway wood sleepers and coal tar samples was estimated by GC-MS, GC-FID, HPLC, UPLC, while enzymatic activity was determined by qualitative enzymatic assay in vitro and UV-visible spectroscopy.