Trichoderma: Evaluation of Its Degrading Abilities for the Bioremediation of Hydrocarbon Complex Mixtures

Hydrocarbons can have very harmful effects on organisms and the environment, and conventional techniques for their removal are expensive and require the use of chemicals and long-term actions. Trichoderma is an ascomycete genus known to be active on different recalcitrant substrates, since it can produce a set of nonspecific extracellular enzymes generally involved in the degradation of lignin. However, the literature concerning the use of Trichoderma to degrade hydrocarbons is still limited. In this work we aimed to investigate the ability of Trichoderma to exploit used engine oil as its sole carbon source for prospective bioremediation of contaminated substrates. Four different strains belonging to Trichoderma asperellum and Trichoderma harzianum species were tested. The fungi were inoculated in direct contact with used engine oil, and after 45 days the samples were analyzed by gas chromatography/mass spectrometry (GC/MS). The results showed that all strains (except Trichoderma asperellum F1020) significantly changed the oil composition, decreasing the aromatic fraction in favor of the aliphatic one. T. harzianum F26, especially, showed a significant reduction of the BTEX (benzene, toluene, ethylbenzene, and the three xylene isomers) and alkylbenzenes fraction and an increase in short-chain aliphatics C1–C20. Enzymatic tests for laccase and peroxidase were also carried out, demonstrating that every strain seems to express a different mode of action