Diversidade de fungos de solos antárticos e prospecção de enzimas ligninolíticas
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Data
2017-05-02
Autores
Wentzel, Lia Costa Pinto [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O estudo de ambientes extremos, como o antártico, pode resultar na descoberta de novos micro-organismos e novos produtos naturais de origem microbiana, visto que ainda pouco se sabe sobre a diversidade e os recursos genéticos presentes nesses locais. Estudos anteriores de prospecção microbiana antártica têm demonstrado que estes organismos representam um nicho potencial de descoberta de novas enzimas, as quais podem apresentar propriedades de interesse em diversos setores de importância sócio-econômica. Nesse contexto, este projeto teve como objetivos avaliar as comunidades de fungos presentes em diferentes amostras de solos antárticos e solos associados às raízes de Colobanthus quitensis e Deschampsia antarctica, as duas únicas plantas vasculares que ocorrem na Antártica marítima, bem como selecionar novos recursos genéticos produtores de enzimas ligninolíticas. Foram obtidos das seis amostras estudadas, 891 isolados de fungos nas duas temperaturas de incubação utilizadas (5ºC e 15 ºC), sendo 141 provenientes de solos e 750 provenientes de solos associados às raízes das duas plantas. Do total, 399 foram leveduras e 492 foram fungos filamentosos. O maior número de isolados foi obtido a partir de uma amostra de solo associado à raiz de C. quitensis. Do total de micro-organismos, 35 apresentaram potencial para a produção de lacase, e 3 apresentaram atividade enzimática ≥ 1 U L-1 para a enzima lignina peroxidase. Os resultados revelaram a presença de 39 diferentes taxa, com representantes dos filos Ascomycota, Basidiomycota e “Zygomycota”, sendo os gêneros mais frequentes Pseudogymnoascus e Leucosporidium. As amostras de solo associado às raízes das duas plantas apresentaram alta riqueza de espécies e alta diversidade em comparação com as amostras de solo, e a diversidade beta da região estudada foi alta, dado que diferentes locais apresentaram um menor compartilhamento de espécies. A composição das comunidades microbianas foi fortemente influenciada por seus locais de coleta. Fatores como a textura do solo e teor de carbono parecem ter influência na composição das comunidades. A temperatura foi um fator significante na composição das comunidades microbianas, com um maior número de isolados e de diferentes taxa obtidos a 15 ºC e a presença de cobertura vegetal no solo pareceu influenciar na diversidade observada. O presente projeto permitiu a ampliação do conhecimento da diversidade de fungos que habitam o ecossistema antártico, bem como possibilitou a obtenção de fungos provavelmente desconhecidos pela ciência (novas espécies e/ou gêneros), além de ter propiciado o isolamento de fungos produtores de enzimas ligninolíticas a baixas temperaturas.
The study of extreme environments, such as the Antarctic, is a potential source for the discovery of new microorganisms and new natural products, since little is known yet about the diversity and the genetic resources present in these sites. Previous studies related to microbial prospecting of antarctic fungi have been showing that these organisms represent a potential niche for the discovery of new enzymes, which can present properties of interest in several important socialeconomic sectors. In this context, the aim of this work was to evaluate the fungi communities from different soil and root-associated soil samples of Colobanthus quitensis and Deschampsia antarctica, the only two species of vascular plants to occur in the maritime Antarctica, as well as to select new genetic resources capable of producing ligninolytic enzimes. From the six samples studied, it was obtained 891 isolates on both employed isolation temperatures (5ºC and 15 ºC), where 141 came from soil and 750 came from root-associated soil. Three hundred and ninety-nine of the total were yeasts and 492 were filamentous fungi. The highest number of isolates obtained was from a root-associated soil sample of C. quitensis. From all isolates, 35 showed laccase production potential, and 3 presented enzymatic activity ≥ 1 U L-1 for the enzyme lignin peroxidase. It was obtained 39 different taxa with representatives of the phyla Ascomycota, Basidiomycota and “Zygomycota”, where the most frequent genera were Pseudogymnoascus and Leucosporidium. The root-associated soil samples showed high species richness and diversity in comparison to the soil samples, and the beta diversity of the studied region was high, given that different sites showed less species sharing. The microbial communities’ composition was strongly influenced by their sampling locations, and factors like soil texture and carbon content seemed to influence this composition. Temperature was significant regarding microbial communities’ composition, with a high number of isolates and different taxa obtained at 15 ºC, and the presence of vegetation cover in soil seemed to influence on the observed diversity. The present study allowed to broaden the knowledge on the diversity of fungi that inhabit the antarctic ecosystem, made possible the acquisition of fungi probably unknown by science (new species and/or new genera), as well as made possible the isolation of ligninolytic enzymes producing fungi at low temperatures.
The study of extreme environments, such as the Antarctic, is a potential source for the discovery of new microorganisms and new natural products, since little is known yet about the diversity and the genetic resources present in these sites. Previous studies related to microbial prospecting of antarctic fungi have been showing that these organisms represent a potential niche for the discovery of new enzymes, which can present properties of interest in several important socialeconomic sectors. In this context, the aim of this work was to evaluate the fungi communities from different soil and root-associated soil samples of Colobanthus quitensis and Deschampsia antarctica, the only two species of vascular plants to occur in the maritime Antarctica, as well as to select new genetic resources capable of producing ligninolytic enzimes. From the six samples studied, it was obtained 891 isolates on both employed isolation temperatures (5ºC and 15 ºC), where 141 came from soil and 750 came from root-associated soil. Three hundred and ninety-nine of the total were yeasts and 492 were filamentous fungi. The highest number of isolates obtained was from a root-associated soil sample of C. quitensis. From all isolates, 35 showed laccase production potential, and 3 presented enzymatic activity ≥ 1 U L-1 for the enzyme lignin peroxidase. It was obtained 39 different taxa with representatives of the phyla Ascomycota, Basidiomycota and “Zygomycota”, where the most frequent genera were Pseudogymnoascus and Leucosporidium. The root-associated soil samples showed high species richness and diversity in comparison to the soil samples, and the beta diversity of the studied region was high, given that different sites showed less species sharing. The microbial communities’ composition was strongly influenced by their sampling locations, and factors like soil texture and carbon content seemed to influence this composition. Temperature was significant regarding microbial communities’ composition, with a high number of isolates and different taxa obtained at 15 ºC, and the presence of vegetation cover in soil seemed to influence on the observed diversity. The present study allowed to broaden the knowledge on the diversity of fungi that inhabit the antarctic ecosystem, made possible the acquisition of fungi probably unknown by science (new species and/or new genera), as well as made possible the isolation of ligninolytic enzymes producing fungi at low temperatures.
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Palavras-chave
Antártica, Fungos adaptados ao frio, Enzimas adaptadas ao frio, Antarctica, Cold adapted fungi, Cold adapted enzymes