Diversidade de fungos decompositores de madeira presentes em ecossistemas brasileiros: bioprospecção de espécies úteis em processo de biodegradação de poluentes aromáticos

Abstract

Woody decay fungi are considered key organisms in the carbon cycling process on the environment due, mainly, to their capacity of degrade lignin. The process of decompose lignocellulosics substrate is possible due to a system of unspecific enzymes produced by some fungi species and that can be utilized for the degradation of other aromatic molecules, natural or synthetic, similar to lignin. Nowadays, the pollutants of major consumption are dyes form textile industry and petroleum and its derivate, which are hazardous recalcitrant to the environmental. This work had the objective to characterize the composition and diversity of fungi present on decaying wood of Brazilian ecosystems and assess it for the capacity of growing using aromatic pollutants as their only source of carbon. Different samples of decaying wood were collected on Caatinga ecosystem and the ecotone between Mata Atlântica/Cerrado and Mata Amazônica/Cerrado. Ninety decay wood fragments were inoculates on 3 different medium containing the azo dye Astrazon or the anthraquinone dye Remazol Brilliant Blue R or crude oil as the unique source of carbon. After 7-15 days, 98 fungal isolates were obtain and grouped in 85 morphotypes according with their distinct characteristics macromorphological and by the PCR microsatellite technique (MSP-PCR), using the oligonucleotide (GTG)5. The isolates with identical banding patterns were confirmed as belonging to the same group and a representant of each group were selected for molecular identification through the sequencing of the internal transcribes spacer region (ITS) of RNA ribosomal gene. The degraders fungi were identify as belonging to the genres Fusarium, Trichoderma, Penicillium, Talaromyces, Cosmospora, Purpureocillium, Acremonium, Pleurostoma, Aspergillus, Exophiala, Lodderomyces, Meyerozyma, Pseudozyma e Sporisorium. The more frequentely species were Hypocrea lixii, Fusarium sp., Meyerozyma carpophila e Pleurostoma ootheca. Caatinga were the biome that presented the most diverse group of species according with Fisher-Ñ index. To assess the capacity of this funig to degrade the pollutants tested, the dry biomass growth on the medium with Astrazon, RBBR and petroleum as the only source of carbon were measured together with the measurement of the fade color by spectofotometria. Fifty five fungi were considered good degraders of this aromatic pollutants, highlighting the species Fusarium oxysporum, F. cf. solani, Purpureocillium lilacinum, Trichoderma sp., Hypocrea lixii, Exophiala cf. oligosperma, Penicillium simplicissimum, Meyerozyma carpophila, M. guilliermondii, Sporisorium sp., Pseudozyma sp., e P. hubeiensis which presents the best degradation profiles. The Astrazon and RBBR mineralization were determined by quantifying of total organic carbon, which showed, for the selected species, that the reduction of color was not linked to the breaking of the carbon chain. The crude oil degradation was determined using high performance liquid chromatography using anthracene as the unique source of carbon. These experiment results were inconclusive and should be repeated.