Despolimerização de Polietilenotereftalato (PET) mediada por fungos filamentosos
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Data
2018-10-08
Autores
Picca, Lusiane Malafatti [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As características de recalcitrância e insolubilidade em água tornam a disposição final de polímeros, um grande problema para sociedade moderna. Estima-se que em 30 anos, a quantidade de garrafas de polietilenotereftalato (PET) presentes no ambiente marinho irá se igualar à quantidade de peixes. Estratégias que programem a reciclagem de polímeros pós-consumo, tais como a despolimerização ou degradação de PET têm sido estudadas. Para contribuir com essa proposta, foram pesquisadas linhagens de fungos filamentosos com potencial para despolimerização de PET. Cem linhagens foram obtidas de diversos ambientes: amostras de água de rios do entorno de uma refinaria e de dentro dessa; cutícula de formiga; solo sob o plantio de Citrus; ar e de fragmentos de garrafa. Os isolados foram submetidos a uma triagem de atividades hidrolíticas para esterases e lipases por: ensaios em placas; análises de alto desempenho (HTS) com sondas esterificadas fluorogênicas com cadeias de 2 e 8 carbonos, e avaliação da capacidade de despolimerização de nanopartículas de PET. Nove isolados foram selecionados por apresentar promissoras atividades enzimáticas e são pertencentes aos gêneros Microsphaeropsis, Mucor, Trichoderma, Westerdykella e Pycnidiophora e seis linhagens foram capazes de converter as nanopartículas de PET em concentrações acima de 0,8% de ácido tereftálico (PTA): Curvularia sp, Trichoderma spp (2), Cladosporium sp e Microsphaeropsis (2). Estudos confirmatórios de fermentação foram conduzidos em fragmentos de PET de garrafas de diferentes cristalinidades. Dados de despolimerização foram obtidos pela quantificação do monômero PTA, bis-2-hidroxietiltereftalato (BHET) e metil-2-hidroxietiltereftalato (MHET), análises de espectroscopia de absorção no infravermelho (FTIR), microscopia eletrônica de varredura (MEV) e avaliações de atividades de lipases e esterases nos líquidos fermentados. As linhagens eleitas liberaram PTA em concentrações acima de 12 ppm, BHET e MHET em concentrações acima de 0,6 ppm e também promoveram alterações na estrutura química e superfície dos fragmentos de PET. Os resultados corroboram que substratos associados a hidrocarbonetos são importantes fontes de microrganismos para aplicação em tecnologias ambientais. Por fim, este trabalho trouxe importante contribuição para estudos de biodegradação de polímeros, uma vez que destacou linhagens até então pouco estudadas para esta aplicação biotecnológica.
Recalcitrance and insolubility in water make the final disposal of polymers, a great problem for modern society. It is estimated that in 30 years, the amount of Polyethylene terephthalate (PET) bottles in the marine environment will match the quantity of fish. Green Strategies that program the recycling of post-consumer polymers such as depolymerization or degradation of PET has been studied. To contribute to this proposal, we investigated filamentous fungi strains with potential for depolymerization of PET. One hundred lines were obtained from several environments: water samples from rivers around a refinery and from within; ant cuticle; soil under the Citrus planting; air and bottle fragments. The isolates were subjected to a screening of hydrolytic activities for esterases and lipases by plaque assays; high performance analyzes (HTS) with fluorogenic esterified probes with chains of 2 and 8 carbons, and evaluation of the depolymerization capacity of PET nanoparticles. Nine isolates were selected for promising enzymatic activities and belong to the genera Microsphaeropsis, Mucor, Trichoderma, Westerdykella and Pycnidiophora and six lines were able to convert the PET nanoparticles to concentrations above 0.8% of terephthalic acid (PTA): Curvularia sp, Trichoderma spp (2), Cladosporium sp and Microsphaeropsis (2). Confirmatory fermentation studies were conducted on PET fragments from different crystallinity bottles. Depolymerization data were obtained by quantification of the PTA monomer, bis-2-hydroxyethylterephthalate (BHET) and methyl-2-hydroxyethylterephthalate (MHET), infrared absorption spectroscopy (FTIR), scanning electron microscopy (SEM) and activities of lipases and esterases in fermented liquids. The selected strains released PTA at concentrations above 12 ppm, BHET and MHET at concentrations above 0.6 ppm and also promoted changes in the chemical structure and surface of the PET fragments. The results corroborate that substrates associated with hydrocarbons are important sources of microorganisms for application in environmental technologies. Finally, this work has made an important contribution to studies of biodegradation of polymers, since it has highlighted lines that have not been studied for this biotechnological application.
Recalcitrance and insolubility in water make the final disposal of polymers, a great problem for modern society. It is estimated that in 30 years, the amount of Polyethylene terephthalate (PET) bottles in the marine environment will match the quantity of fish. Green Strategies that program the recycling of post-consumer polymers such as depolymerization or degradation of PET has been studied. To contribute to this proposal, we investigated filamentous fungi strains with potential for depolymerization of PET. One hundred lines were obtained from several environments: water samples from rivers around a refinery and from within; ant cuticle; soil under the Citrus planting; air and bottle fragments. The isolates were subjected to a screening of hydrolytic activities for esterases and lipases by plaque assays; high performance analyzes (HTS) with fluorogenic esterified probes with chains of 2 and 8 carbons, and evaluation of the depolymerization capacity of PET nanoparticles. Nine isolates were selected for promising enzymatic activities and belong to the genera Microsphaeropsis, Mucor, Trichoderma, Westerdykella and Pycnidiophora and six lines were able to convert the PET nanoparticles to concentrations above 0.8% of terephthalic acid (PTA): Curvularia sp, Trichoderma spp (2), Cladosporium sp and Microsphaeropsis (2). Confirmatory fermentation studies were conducted on PET fragments from different crystallinity bottles. Depolymerization data were obtained by quantification of the PTA monomer, bis-2-hydroxyethylterephthalate (BHET) and methyl-2-hydroxyethylterephthalate (MHET), infrared absorption spectroscopy (FTIR), scanning electron microscopy (SEM) and activities of lipases and esterases in fermented liquids. The selected strains released PTA at concentrations above 12 ppm, BHET and MHET at concentrations above 0.6 ppm and also promoted changes in the chemical structure and surface of the PET fragments. The results corroborate that substrates associated with hydrocarbons are important sources of microorganisms for application in environmental technologies. Finally, this work has made an important contribution to studies of biodegradation of polymers, since it has highlighted lines that have not been studied for this biotechnological application.
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Palavras-chave
Biodegradação, Polímeros, Catálise enzimática, Microrganismos, Biodegradation, Polymers, Enzymatic catalysis, Microorganisms