Utilização de fungos filamentosos na biorremediação da 3,4-dicloroanilina e atrazina

Abstract

Aromatic amines (AA) are one of the classes of compounds most used by industry, in the manufacture of various products, and are among the pollutants most found in both soil and water. The majority of pollutants in this class are derived from dyes and pesticides such as atrazine (ATZ) and 3,4-dichloroaniline (3,4-DCA). One of the alternatives for decontaminating soil and water containing toxic AA is bioremediation, a technique that uses plants, microorganisms or their enzymes to treat polluted sites and recover their original condition. There are few studies using filamentous fungi in AA bioremediation processes, and N-acetylation can be used as a tool, which is an enzymatic process catalyzed by the enzyme arylamine N-acetyltransferase (NAT) found in fungi and other organisms. Thus, the present project aimed to evaluate the capacity of filamentous fungi from the Pantanal and Cerrado mycobiota in the bioremediation of ATZ and 3,4-DCA. A selection was made from 13 strains of filamentous fungi from the genera Aspergillus, Chaetomium, Cladosporium, Mucor and Trichoderma to evaluate the ability to biotransform AA, the 4 strains selected for 3,4-DCA and 9 strains for ATZ. They were subjected to biotransformation tests, where the strains tolerated a concentration of 500 μM for 3,4-DCA, promoting biotransformation into N-acetylated 3,4-DCA (3,4-DCA-Ac) and reduced phytotoxicity in experiments with Lactuca sativa seeds. The conversion of AA into N-acetylated products (AA-Ac) also proved to be efficient in reducing cytotoxic and genotoxic effects in tests carried out with the human keratinocyte cell line (HaCaT). In biotransformation with ATZ, the strains tolerated a concentration of 232 mM, except for A. terreus 31, which had a maximum tolerated concentration of 1 mM. When comparing morphological aspects of the liquid culture medium, mycelial growth and pHs, the strains did not show morphological differences in biomass between control and samples with ATZ, they showed total consumption of ATZ through CCD monitoring and the medium was acidified, changing the pH. In bioremediation tests in plates and soil, the strains reduced the phytotoxic effects of ATZ through the absorption mechanism, confirmed by the higher percentage of ATZ extracted from the mycelial mass after 5 days of experimentation in analysis by HPLC-HRMS ESI/TOF, with the exception of Trichoderma harzianum 27, where the highest percentage was found in the extracellular environment. However, among the 9 strains tested to bioremediate ATZ, the fungi Aspergillus niger and Mucor sp. showed the best results in reducing the phytotoxicity and absorption capacity of ATZ, proving to be promising candidates for moving forward with ATZ bioremediation studies.