Development and evaluation of ligninolytic fungal consortia for the bioremediation of wooden railway crossties

Abstract

Creosote is widely used as wood preservative due to its efficient properties as biocide, and it 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 it). The aim of this research is to investigate the potential of selected basidiomycetes and ascomycetes, in particular white-rot fungi for the bioremediation of creosote in expended wood crossties and to develop fungal consortia with faster biomass growth rate and/or able to enhance the production of ligninolytic enzymes in order to increase the efficiency of the mycoremediation process. Fungal species, previously selected for their resistance to different pollutant concentrations, have been further investigated to assess their ability to produce ligninolytic enzymes, such as laccase (E.C. 1.10.3.2), lignin peroxidase (E.C. 1.11.1.14), manganese dependent peroxidase (E.C. 1.11.1.13), as a parameter to determine their potential for mycoremediation. 36 different dual co-culture consortia were investigated to evaluate their ability to improve the bioremediation 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.