Fungos basidiomicetos de solos de recuo da geleira Collins (Antártica): caracterização taxonômica e aplicação ambiental
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Data
2022-03-07
Autores
Farias, Gabriele Santana de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O continente antártico possui condições ambientais extremas, as quais promovem uma pressão seletiva e resulta no desenvolvimento de adaptações para que os microorganismos possam sobreviver. Devido a mudanças climáticas, as geleiras da Antártica estão sofrendo um processo de retração, propiciando um novo hábitat para microorganismos no solo recém-exposto. Fungos basidiomicetos provenientes de solos de recuo da geleira Collins, coletados na OPERANTAR XXXIII (2015), foram utilizados no presente estudo, com o objetivo de avançar na identificação taxonômica e verificar a capacidade de descoloração, destoxificação e adsorção do corante azo Vermelho Congo, bem como a capacidade de se desenvolver na presença do óleo diesel. Os isolados foram identificados como Pholiota cf. baeosperma (320 e 344), Schizophyllum sp. (58) e Aleurodiscus sp. (177). Os melhores resultados para descoloração, nas concentrações de 50 e 100 mg/L de corante, foram apresentados pelos fungos Pholiota cf. baeosperma 320 e Schizophyllum sp. 58 após sete dias de cultivo a 25 °C. Todos os fungos apresentaram atividade enzimática para lacase, sendo a maior atividade (8,8 U/L) obtida para o fungo Pholiota cf. baeosperma 320 na concentração de 100 mg/L do corante. Na cinética de descoloração, Pholiota cf. baeosperma 320 e 344 apresentaram uma média de 70% de descoloração desde o primeiro dia do experimento, enquanto Schizophyllum 58 alcançou um máximo de descoloração (acima de 90%) no sétimo dia do experimento e Aleurodiscus sp. 177 apresentou uma diminuição de 10 % na descoloração no sétimo dia do experimento. Quanto à fitotoxicidade, os fungos Aleurodiscus sp. 177 e Pholiota cf. baeosperma 320 e 344 diminuíram em 100 % a toxicidade na concentração de 50 mg/L e, ao aumentar a concentração para 100 mg/L, a toxicidade após o tratamento foi maior, o que indica que compostos tóxicos podem ter sido gerados na quebra da molécula do corante Vermelho Congo. Para o fungo Schizophyllum sp. 58, a toxicidade diminuiu nas duas concentrações testadas. O fungo Aleurodiscus sp. 177 foi o que apresentou o maior resultado de adsorção (96 %), melhorando o desempenho em relação ao ensaio com o micélio ativo, onde a descoloração foi de 55 %. O fungo Schizophyllum sp. 58 não apresentou diferença entre os ensaios de adsorção e descoloração. Para os fungos Pholiota cf. baeosperma 320 e 344 a adsorção pelo micélio inativo foi menor do que no ensaio com os fungos ativos. Os dados relacionados com a detecção de metabólitos de degradação do Vermelho Congo (análises de GC-MS) indicam que a descoloração do corante pelo fungo Pholiota cf. baeosperma 344 ocorreu principalmente por mecanismos enzimáticos, enquanto que para o fungo Schizophyllum sp. 58 o principal mecanismo foi a adsorção. Alguns metabólitos detectados como éster de ácido ftálico, ácido oxálico e benzeno são fitotóxicos. O fungo Schizophyllum sp. 58 foi o único que apresentou crescimento micelial em meio de cultura contendo apenas o óleo diesel como fonte de carbono. Os resultados obtidos no presente estudo indicam que os fungos basidiomicetos de origem Antártica podem ser uma nova alternativa para a biorremediação de compostos xenobióticos poluentes ambientais.
The Antarctic continent has extreme environmental conditions, which promote selective pressure and result in the development of adaptations for microorganisms to survive. Due to climate change, the Antarctic glaciers are undergoing a retreating process, providing new habitat for microorganisms in the newly exposed soil. Basidiomycete fungi from Collins Glacier retreat soils, collected in the OPERANTAR XXXIII (2015), were used in this study to advance in the taxonomic identification and to verify their ability to decolorize, detoxify and adsorb the azo dye Congo Red, as well as their ability to grow in the presence of diesel oil. The isolates were identified as Pholiota cf. baeosperma (320 and 344), Schizophyllum sp. (58) and Aleurodiscus sp. (177). The best results for decolorization, at concentrations of 50 and 100 mg/L of the dye, were presented by the fungi Pholiota cf. baeosperma 320 and Schizophyllum sp. 58 after 7 days of cultivation at 25 °C. All fungi showed lacase enzymatic activity, with the highest activity (8.8 U/L) obtained for Pholiota cf. baeosperma 320 at 100 mg/L of the dye. In the decolorization kinetics, Pholiota cf. baeosperma 320 and 344 presented an average of 70% of decolorization since the first day of the experiment, while Schizophyllum 58 reached a maximum of decolorization (above 90%) on the seventh day of the experiment and Aleurodiscus sp. 177 presented a 10% decrease in decolorization on the seventh day of the experiment. Regarding phytotoxicity, the fungi Aleurodiscus sp. 177 and Pholiota cf. baeosperma 320 and 344 decreased 100 % of the toxicity at the concentration of 50 mg/L, and when the concentration was increased to 100 mg/L, the toxicity after the treatment was higher, which indicates that toxic compounds may have been generated in the breakdown of the Congo Red dye molecule. For the fungus Schizophyllum sp. 58, the toxicity decreased at the two concentrations tested. The fungus Aleurodiscus sp. 177 showed the highest adsorption result (96 %), improving the performance compared to the assay with active mycelium, where the decolorization was 55 %. The fungus Schizophyllum sp. 58 showed no difference between the adsorption and decolorization assays. For the fungi Pholiota cf. baeosperma 320 and 344 the adsorption by the inactive mycelium was lower than in the assay with the active fungi. Data related to the detection of Congo Red degradation metabolites (GC-MS analyses) indicate that dye decolorization by the fungus Pholiota cf. baeosperma 344 occurred mainly by enzymatic mechanisms, while for the fungus Schizophyllum sp. 58 the main mechanism was adsorption. Some metabolites detected such as phthalic acid ester, oxalic acid, and benzene are phytotoxic. The fungus Schizophyllum sp. 58 was the only one that showed mycelial growth in culture medium containing only diesel oil as a carbon source. The results obtained in the present study indicate that basidiomycete fungi of Antarctic origin can be a new alternative for the bioremediation of xenobiotic environmental pollutants compounds.
The Antarctic continent has extreme environmental conditions, which promote selective pressure and result in the development of adaptations for microorganisms to survive. Due to climate change, the Antarctic glaciers are undergoing a retreating process, providing new habitat for microorganisms in the newly exposed soil. Basidiomycete fungi from Collins Glacier retreat soils, collected in the OPERANTAR XXXIII (2015), were used in this study to advance in the taxonomic identification and to verify their ability to decolorize, detoxify and adsorb the azo dye Congo Red, as well as their ability to grow in the presence of diesel oil. The isolates were identified as Pholiota cf. baeosperma (320 and 344), Schizophyllum sp. (58) and Aleurodiscus sp. (177). The best results for decolorization, at concentrations of 50 and 100 mg/L of the dye, were presented by the fungi Pholiota cf. baeosperma 320 and Schizophyllum sp. 58 after 7 days of cultivation at 25 °C. All fungi showed lacase enzymatic activity, with the highest activity (8.8 U/L) obtained for Pholiota cf. baeosperma 320 at 100 mg/L of the dye. In the decolorization kinetics, Pholiota cf. baeosperma 320 and 344 presented an average of 70% of decolorization since the first day of the experiment, while Schizophyllum 58 reached a maximum of decolorization (above 90%) on the seventh day of the experiment and Aleurodiscus sp. 177 presented a 10% decrease in decolorization on the seventh day of the experiment. Regarding phytotoxicity, the fungi Aleurodiscus sp. 177 and Pholiota cf. baeosperma 320 and 344 decreased 100 % of the toxicity at the concentration of 50 mg/L, and when the concentration was increased to 100 mg/L, the toxicity after the treatment was higher, which indicates that toxic compounds may have been generated in the breakdown of the Congo Red dye molecule. For the fungus Schizophyllum sp. 58, the toxicity decreased at the two concentrations tested. The fungus Aleurodiscus sp. 177 showed the highest adsorption result (96 %), improving the performance compared to the assay with active mycelium, where the decolorization was 55 %. The fungus Schizophyllum sp. 58 showed no difference between the adsorption and decolorization assays. For the fungi Pholiota cf. baeosperma 320 and 344 the adsorption by the inactive mycelium was lower than in the assay with the active fungi. Data related to the detection of Congo Red degradation metabolites (GC-MS analyses) indicate that dye decolorization by the fungus Pholiota cf. baeosperma 344 occurred mainly by enzymatic mechanisms, while for the fungus Schizophyllum sp. 58 the main mechanism was adsorption. Some metabolites detected such as phthalic acid ester, oxalic acid, and benzene are phytotoxic. The fungus Schizophyllum sp. 58 was the only one that showed mycelial growth in culture medium containing only diesel oil as a carbon source. The results obtained in the present study indicate that basidiomycete fungi of Antarctic origin can be a new alternative for the bioremediation of xenobiotic environmental pollutants compounds.
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Palavras-chave
Basidiomicetos antárticos, Biorremediação, Vermelho Congo, Óleo diesel, Geleira Collins, Antarctic basidiomycete, Bioremediation, Congo red, Diesel oil, Collins glacier