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Trametes coccinea IDEA, a super laccase-producer fungus isolated from a natural asphalt lake: Tolerance and biotransformation of aromatics polycyclic hydrocarbons

Abstract:

Polycyclic aromatic hydrocarbons (HPAs) are toxic compounds that are not easily degraded under natural conditions. The goal of the present study was to isolate, identify and phenotypically characterize hydrocarbonoclastic fungi from extreme environments that are capable of tolerating HPAs, such as Trametes coccinea IDEA, that was isolated from the Natural Asphalt Lake of Guanoco in Venezuela. To study its tolerance to HPAs, the fungus was exposed to different concentrations of naphthalene, phenanthrene, and pyrene (0, 2.5, 25, 50, 100, 200, 400, 800, and 1600 mg/L). Subsequently, in a test in a liquid culture medium, the effect of these HPAs on the activity of enzymes of the lignin-degrading enzymes system (LDES) was studied, and the possible variations in toxicity levels using Lactuca sativa as bioindicator. The results showed a high tolerance to pyrene, followed by naphthalene and phenanthrene. Strong induction of laccase activity was observed at the presence of naphthalene (167.96 U/mgP) and pyrene (124.89 U/mgP) compared with the control, while with phenanthrene a low activity was obtained (88.67 U / mgP). Interestingly, a generation of more toxic byproducts was observed when naphthalene and phenanthrene were biotreated by the fungus, while the toxicity level of pyrene decreased significantly. T. coccinea IDEA has a high potential to be used in hydrocarbon bioremediation strategies, which must be monitored by ecotoxicological analysis to detect the possible toxicity levels variations in the partially biotransformed products.