Fungi in pressmud composting: diversity, genomics and biotechnological aspects
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Data
2016-11-18
Autores
Oliveira, Tássio Brito de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A torta de filtro é gerada após o processo de filtração do caldo de cana (cerca de 26 a 40 kg por t de cana) e geralmente é utilizada como fertilizante nas lavouras sem qualquer tratamento prévio. A diversidade de fungos presentes na torta de filtro fresca e no processo de compostagem desse substrato foi acessada utilizando sequenciamento em larga escala. Além disso, fungos tolerantes ao calor foram isolados e avaliados quanto à capacidade de produzir enzimas de degradação da biomassa (celulase, xilanase, lacase e poligalacturonase). Considerando que esse grupo de fungos carece de uma revisão taxonômica atual, aproveitamos as recentes mudanças proporcionadas pelo Código de Nomenclatura para Algas, Fungos e Plantas para gerar uma revisão taxonômica do grupo. Uma gama de patógenos oportunistas foi encontrada entre os taxa mais abundantes na torta de filtro fresca, como Lomentospora prolificans (43,13%), Trichosporon sp. (10,07%), Candida tropicalis (7,91%) e Hormographiella aspergillata (8,19%). Isso indica que a torta de filtro pode ser uma potencial fonte de fungos patogênicos, apresentando riscos para a saúde humana se aplicado como fertilizante sem qualquer tratamento. No entanto, o processo de compostagem reduz efetivamente a carga desses fungos. Além disso, cria um ambiente interessante para fungos capazes de produzir enzimas com potencial aplicação biotecnológica, uma vez que todos os 110 isolados avaliados foram capazes de produzir, pelo menos, uma das enzimas avaliadas. Além disso, a análise comparativa de genes codificantes para peptidases presentes nos genomas de fungos termofílicos (encontrados em sistemas de compostagem) e mesofílicos mostrou que a termofilia levou à várias adaptações para a termoestablidade enzimática.
Pressmud is derived from sugarcane juice filtrate (around 26 to 40 kg per ton of sugarcane) and it is mainly used as fertilizer in crops without prior treatment. Here, the fungal diversity present in both fresh and composting pressmud was revealed by 454 pyrosequencing. In addition, heat-tolerant fungi were isolated and surveyed for their repertoire of biomass-degrading enzymes (cellulase, xylanase, laccase and polygalacturonase). The fact that the taxonomy of such organisms is still obscure, we revised their taxonomy in the light of the recent changes adopted in the Code of Nomenclature for Algae, Fungi and Plants. A wide range of opportunistic pathogens was found among the most abundant taxa in fresh pressmud, such as Lomentospora prolificans (43.13%), Trichosporon sp. (10.07%), Candida tropicalis (7.91%), and Hormographiella aspergillata (8.19%). This indicates that fresh pressmud may be a source of human pathogenic fungi, presenting a potential threat to human health if applied as fertilizer without treatment. Composting of the pressmud effectively reduces the load of such fungi. Furthermore, the composting system creates an interesting environment for fungi able to produce enzymes with biotechnological applications, since all the 110 isolates screened were able to produce at least one of the tested enzymes.Furthermore, comparative analysis of peptidases genes encoded by thermophilic (generally found in composting systems) and mesophilic fungi showed that thermophyly selected for thermostable enzymes.
Pressmud is derived from sugarcane juice filtrate (around 26 to 40 kg per ton of sugarcane) and it is mainly used as fertilizer in crops without prior treatment. Here, the fungal diversity present in both fresh and composting pressmud was revealed by 454 pyrosequencing. In addition, heat-tolerant fungi were isolated and surveyed for their repertoire of biomass-degrading enzymes (cellulase, xylanase, laccase and polygalacturonase). The fact that the taxonomy of such organisms is still obscure, we revised their taxonomy in the light of the recent changes adopted in the Code of Nomenclature for Algae, Fungi and Plants. A wide range of opportunistic pathogens was found among the most abundant taxa in fresh pressmud, such as Lomentospora prolificans (43.13%), Trichosporon sp. (10.07%), Candida tropicalis (7.91%), and Hormographiella aspergillata (8.19%). This indicates that fresh pressmud may be a source of human pathogenic fungi, presenting a potential threat to human health if applied as fertilizer without treatment. Composting of the pressmud effectively reduces the load of such fungi. Furthermore, the composting system creates an interesting environment for fungi able to produce enzymes with biotechnological applications, since all the 110 isolates screened were able to produce at least one of the tested enzymes.Furthermore, comparative analysis of peptidases genes encoded by thermophilic (generally found in composting systems) and mesophilic fungi showed that thermophyly selected for thermostable enzymes.
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Palavras-chave
Pirosequenciamento, Cana-de-açúcar, Enzimas lignocelulolíticas, Tratamento de resíduo, Fungos termofílicos, Fungos termotolerantes, Pyrosequencing, Sugarcane, Lignocellulolytic enzymes, Residue treatment, Thermophilic fungi, Thermotolerant fungi