Influence of creosote-polluted substrate on the bioremediation-potential microscopic fungi in the rhizosphere of plants

Wooden sleepers used in railways are impregnated with preservatives with fungicidic and bactericidic properties, which contain a large amount of harmful polycyclic aromatic hydrocarbons (PAHs). The aim of this research was to reveal the type of fungi in the rhizosphere of plants, which tolerate pollutants and can be involved in bioremediation process of creosote-contaminated used wooden railway sleepers. Tagetes patula grown in the substrate with 12.5% creosote impregnated used wooden sleepers chips additive is characterized by the most intensive root development and the biggest population of active fungi, therefore it is recommended for further investigation. Number of colonies of fungi in the rhizosphere of investigated plants decreased in many cases by increasing the amount of sleepers chips additive in substrate, however it was greater in the substrates with creosote treated wooden sleepers chips additives (12.5, 25 and 37.5% wooden sleepers chips) than in the pure substrate and various substrates with additives of pure Pinus sylvestris chips. This is a pioneering study searching for the local fungi species in Lithuania, which can be further utilized for the bioremediation of PAHs.