Avaliação química e toxicológica de solo contaminado por HPAs submetido à biodegradação pelo fungo basidiomiceto Pycnoporus sanguineus

Abstract

Polycyclic Aromatic Hydrocarbons (PAHs) are organic compounds exclusively formed by carbon and hydrogen atoms and organized in different arrangements produced during the incomplete combustion of the organic matter, being resulted from natural and antropogenic sources. The presence of PAHs is due to the burning processes and oil spills and the identity of the mixture of the PAHs in different sources depends on the some physical factors such as temperature and pressure. These compounds present very good solubility in lipids and are easily absorbed in the lungs, intestines and skin of the human and animals. PAHs are metabolized by enzymes in activated compounds reactive with nucleophlilic groups present in cellular macromolecules. The DNA adducts formation is a crucial step to the chemical carcinogenicity of these xenobionts. A strategy to the PAH reduction in contaminated soils is the bioremediation using the white rot fungi species, by its low costs and efficiency in the decrease of these compounds. The present work aimed to evaluate parameters in the Pycnoporus sanguineus growing, estimate differences in the PAH concentrations in soils treated or not with fungi, and evaluate the toxicity pos treatment in vegetal model using lettuce (Lactuca sativa) and in invertebrate (Artemia salina). Among the 16 priority PAHs listed by United States Environmental Protection Agency (US EPA) 8 compounds presented degradation with reduction percents varying from 44.7%, in the case of the fluoranthene, to 100% considering the anthracene. It were observed significant differences in the germination rate between non inoculated and inoculated samples. The Effective Concentration to the inhibition of 50% of the germination in lettuce seeds (EC50) was 0.32 g/mL and 0.45 g/mL considering the treated and non treated soil respectively, 35 days after the fungi inoculation. The concentration necessary to result death of 50% of the exposed group (LC50) was 3.84 μg/ to inoculated soil with fungi and 23.3 μg/mL to non inoculated one. Both seed and LC50 tests showed an increase of the toxicity of the PAH contaminated soils after the Pycnoporus sanguineus treatment.