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Abstract(s)
Nos últimos anos, os problemas ambientais têm assumido uma crescente gravidade, principalmente devido ao crescimento excessivo da população e à atividade industrial, incluindo a indústria têxtil. O presente trabalho teve como foco a identificação polifásica do isolado de levedura LIVST11, um isolado de águas residuais com efluentes têxteis e que apresenta capacidade para descoloração de corantes têxteis. O isolado LIVST11 foi caracterizado em termos morfológico, fisiológico e bioquímicos através de metodologias de caracterização clássicas e meios cromogénicos. Para além disso, também foi realizada a sequenciação de genes relevantes e, do genoma completo e análise filogenética. O isolado LIVST11 foi identificado como pertencente ao género Candida. Para complementar a identificação, realizaram-se estudos genotípicos que confirmaram a dificuldade em atribuir com elevado grau de confiança uma identificação ao táxon espécie. O estudo do genoma do isolado LIVST11 confirmou os resultados supra referidos e acrescentou dados que parecem sustentar uma nova definição de espécie. O isolado LIVST11 apresentou maior homologia com a Candida cabralensis, usando o amplicon ITS. A árvore filogenética, inferida pelo método de Neighbor-joining, indicou uma espécie estreitamente relacionada com a C. cabralensis, ou eventualmente uma estirpe diferente da mesma espécie. O estudo do isolado LIVST11 ao nível fenotípico permitiu obter evidências que reforçam a proposta de uma espécie diferente de C. cabralensis, sobretudo relacionada com as diferenças entre a capacidade de fermentar diferentes hidratos de carbono pelo isolado LIVST11 que não existe para a espécie C. cabralensis descrita. O isolado LIVST11 apresenta capacidade para descolorar vários corantes têxteis incluindo everzol (navy, azul, vermelho e amarelo), azul supra everdirect e azul procion, para além de alguns efluentes têxteis (everzol (navy, azul, vermelho e amarelo), azul supra everdirect e indigo). Em todos os corantes e efluentes têxteis testados verificou-se que o isolado LIVST11 foi capaz de descolorar, pelo menos, 50% do corante presente, após 48 h. O mecanismo de descoloração usado pelo isolado ainda não é conhecido. As atividades enzimáticas testadas para o isolado em estudo incluiram a peroxidase dependente de manganês, a peroxidase independente de manganês, a lacase, a lignina-peroxidase, a oxidoredutase, a tirosinase e a azoredutase. Porém, a única atividade detetada foi da enzima oxidorredutase (0,001μg.min-1). O extrato intracelular foi utilizado para a separação das proteínas presentes através do FPLC, o que permitiu a purificação das frações proteicas, que foram posteriormente testadas. Os resultados evidenciam uma fração proteica que apresentou atividade enzimática para a oxidorredutase (0,003 μg.min-1) e com peso molecular de 43 KDa como esperado para estas enzimas. Concluindo, o isolado LIVST11 parece ser uma nova espécie de levedura do género Candida com uma interessante capacidade de descoloração de corantes têxteis e de águas residuais de indústrias têxteis. No entanto, os resultados revelaram a necessidade de clarificar e confirmar a identificação como nova espécie e aprofundar o mecanismo responsável para capacidade de descoloração do isolado.
Lately, environmental problems have become increasingly critical and more frequent, mostly due to the increased population growth and industrial activity, namely the textile industry. The present research work focused on the LIVST11 yeast isolate polyphasic identification, which was isolated from wastewater and possesses the ability to decolourise several dyes. LIVST11 isolate was morphologically, physiologically and biochemically characterised thru classical approaches and chromogenic media. In addition, genotypic identification was performed thru sequencing of relevant genes, as well as whole genome sequencing and phylogenetic analysis. According to morphological, physiological and biochemical assays, LIVST11 isolate was preliminarily identified as belonging to genera Candida. The results obtained in molecular biology assays showed that it is not possible to infer the attribution of a species with high confidence to the yeast under study. The analysis of the yeast LIVST11 genome confirmed the previous results and added data that might support a new species definition. The LIVST11 isolate presented the highest homology with C. cabralensis based on amplicon ITS. The evolutionary relationship, as inferred using Neighbor-joining method, indicated a closely related species to C. cabralensis, or a perhaps a different strain of that same species. At the phenotypic level, evidence was obtained that reinforces that LIVST11 isolate may be a different species from C. cabralensis, as for example, C. cabralensis does not ferment several carbohydrates that LIVST11 is able to. LIVST11 isolate presented decolourisation abilities for several dyes, including everzol (navy, blue, red and yellow), blue supra everdirect and navy procion and effluents (everzol (navy, blue, red and yellow), blue supra everdirect, indigo). For all textile dyes and effluents tested it was found that LIVST11 isolate was able to decolourise at least 50% of the dye present after 48 h. The decolourisation mechanism is still unknown. LIVST11 isolate was tested for manganese-dependent peroxidase, manganese-independent peroxidase, laccase, lignin-peroxidase, oxidoreductase, tyrosinase and azoreductase enzymatic activities. However, only oxidoreductase activity was detected (0.001μg.min-1). Intracellular extract was used to perform protein separation trough FPLC, which allowed the purification of a protein fraction that showed oxidoreductase activity (0.003 μg.min-1) and its molecular weight was around 43 KDa as expected for similar enzymes. The LIVST11 isolate appears to be a new species of Candida genera with a promising decolourisation capacity for textile dyes and wastewaters of textile industries. However, the results revealed the need for further studies to confirm the new species proposal and, in addition, to study the mechanism behind its decolourisation abilities.
Lately, environmental problems have become increasingly critical and more frequent, mostly due to the increased population growth and industrial activity, namely the textile industry. The present research work focused on the LIVST11 yeast isolate polyphasic identification, which was isolated from wastewater and possesses the ability to decolourise several dyes. LIVST11 isolate was morphologically, physiologically and biochemically characterised thru classical approaches and chromogenic media. In addition, genotypic identification was performed thru sequencing of relevant genes, as well as whole genome sequencing and phylogenetic analysis. According to morphological, physiological and biochemical assays, LIVST11 isolate was preliminarily identified as belonging to genera Candida. The results obtained in molecular biology assays showed that it is not possible to infer the attribution of a species with high confidence to the yeast under study. The analysis of the yeast LIVST11 genome confirmed the previous results and added data that might support a new species definition. The LIVST11 isolate presented the highest homology with C. cabralensis based on amplicon ITS. The evolutionary relationship, as inferred using Neighbor-joining method, indicated a closely related species to C. cabralensis, or a perhaps a different strain of that same species. At the phenotypic level, evidence was obtained that reinforces that LIVST11 isolate may be a different species from C. cabralensis, as for example, C. cabralensis does not ferment several carbohydrates that LIVST11 is able to. LIVST11 isolate presented decolourisation abilities for several dyes, including everzol (navy, blue, red and yellow), blue supra everdirect and navy procion and effluents (everzol (navy, blue, red and yellow), blue supra everdirect, indigo). For all textile dyes and effluents tested it was found that LIVST11 isolate was able to decolourise at least 50% of the dye present after 48 h. The decolourisation mechanism is still unknown. LIVST11 isolate was tested for manganese-dependent peroxidase, manganese-independent peroxidase, laccase, lignin-peroxidase, oxidoreductase, tyrosinase and azoreductase enzymatic activities. However, only oxidoreductase activity was detected (0.001μg.min-1). Intracellular extract was used to perform protein separation trough FPLC, which allowed the purification of a protein fraction that showed oxidoreductase activity (0.003 μg.min-1) and its molecular weight was around 43 KDa as expected for similar enzymes. The LIVST11 isolate appears to be a new species of Candida genera with a promising decolourisation capacity for textile dyes and wastewaters of textile industries. However, the results revealed the need for further studies to confirm the new species proposal and, in addition, to study the mechanism behind its decolourisation abilities.
Description
Keywords
Levedura Identificação polifásica Descoloração de corantes têxteis Descoloração de efluentes têxteis Atividade enzimática Yeast Polyphasic identification Textile dye decolourisation Textile effluent decolourisation Enzymatic activity