Soil colonization by Trametes versicolor grown on lignocellulosic materials: Substrate selection and naproxen degradation

Abstract

The ability of Trametes versicolor to degrade soil pollutants has been widely studied. However, the use of such fungus in real soil applications has lead to dissimilar results mainly due to soil colonization limitations. Therefore, it is important to investigate techniques to improve the survival of this white rot fungus in soils. In the present study, several processed and unprocessed low-cost lignocellulosic substrates were employed as inoculum carriers for fungal growth prior to application in soil for bioaugmentation. The fungal growth was determined by means of laccase activity and ergosterol determinations; additionally, the degrading capacity was measured by the naproxen degradation test (ND24). Although T. versicolor was able to colonize all materials, the colonization and enzymatic production was higher on processed agricultural wastes with relative low C/N ratios than in raw lignocellulosic substrates. Soil colonization was successful under both sterile and non-sterile conditions when amended with processed agricultural wastes, yielding even higher laccase production in non-sterile conditions. Moreover, T. versicolor was able to degrade significant amounts of spiked naproxen after 24 h in sterile and non-sterile soil cultures, showing the best results when using a material based on wheat straw as carrier.