Isolamento de fungos filamentosos produtores de inulinase

• Autor(a) principal: Castanon, Francisco Singulani
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5363
• topic: Yacon; Inulina; Ilunilase; Fusarium oxyporum; Yacon; Inulin; Ilunilase; Fusarium oxyporum; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::MICROBIOLOGIA AGRICOLA

The inulinases present a great variety of applications, such as the production of fructose syrup, bioethanol and fructooligosaccharides. The industrial versatility presented by these enzymes drives the discovery of new sources of microbial inulinase. In this study, 48 fungi were isolated from the rhizosphere of yacon tuber (Polymnia sanchifolia). The criteria to screening the fungi producers of inulinase were: growth in inulin as unique carbon source and enzyme activitiy by the DNS method. Six promising fungi were selected for the analysis of halo formation by inulin hydrolysis and molecular identification using the ITS rDNA region. For the following studies, the fungus Fusarium oxysporum F6 was selected for having the best production of inulinase and the conditions of inulinase production by this fungus were studied. The best enzyme production occurred at 72 h of growth in minimal medium with 2% inulin. Through the response surface methodology using solid-state fermentation, it was possible to estimate that the increase of the inulin concentration affected the inulinase production by this fungus, reaching a production of up to 2.2 U/ml of inulinase. Optimal activity was observed at 50 °C and pH 5.5. The thin layer chromatography showed that the enzyme has endo-inulinase activity. Comparison of the amino acid sequence of F. oxysporum f. sp. cubense 4 with other fungal inulinases reinforce this characteristic, given the presence of conserved regions with the sequences of other endo-inulinase. The phylogenetic analysis also showed a similarity between the amino acid sequences encoding fungal endo-inulinase. This study demonstrated that the yacon tuber is a good source for the isolation of fungal inulinase producers because a reasonable number of isolates were obtained in trials using this source. The fungus Fusarium oxysporum F6 showed the greatest potential for inulinase production, mainly in solid state fermentation. The fungus Staphylotrichum boninense was also isolated and inulinase production of this fungus will be studied in more detail, due to the reports of their differential production of secondary metabolites by this fungus.