Effects of biological pre-treatment of lignocellulosic waste with white-rot fungi on the stimulation of 14C-phenanthrene catabolism in soils

The enhancement of phenanthrene catabolism in soils amended with lignocellulosic waste material (spent brewery grains) was investigated. The soils were pre-treated with five white-rot fungi (Phanerochaete chrysosporium, Trametes versicolor, Irpex lateus, Pleurotus ostreatus, and Bjerkandera adusta). The changes in the kinetics of 14C-phenanthrene mineralisation (lag phases, the fastest rates and the overall extents) were measured in the inoculated, PAH-amended soils over time (1-100 d). Changes in the ligninolytic (laccase, lignin peroxidase and manganese peroxidase) and non-ligninolytic (beta-glucosidase and phosphatase) enzymatic activities were also assessed. Overall results revealed that the amendment of fungal pre-treated SBG influenced the kinetics of mineralisation of 14C-phenanthrene as well as the enzymatic activities in soils. Soil inoculated with fungal pretreated SBG caused reductions in lag phases as well as higher rates and extents of 14C-phenanthrene mineralisation in the following trend T. versicolor > B. adusta > P. chrysosporium = P. ostreatus > I. lateus. Furthermore, the extents of mineralisation generally reduced as levels of ligninolytic enzyme decreased, while the nonligninolytic enzymes increased with soil-PAH contact time in all amendment conditions. These findings provided an insight on the potential of biological pre-treatment of waste materials for enhanced carbon, energy and nutrients on the bioactivities and biodegradation of organic pollutants which may be applicable during in situ remediations of contaminated soil.