Filamentous fungi able to hydrolyse inulin have been isolated from the rhizosphere of plants whose roots contain this polysaccharide. This study reports results concerning the isolation and identification of filamentous fungi from the soil used for sunflower cultivation and from the sunflower rhizosphere cultivated in field and in greenhouse. Fungi were evaluated according to their capacity to hydrolyse inulin and the variation in the diversity of these fungi during the plant's life cycle was also accessed. Forty-nine species of filamentous fungi were isolated. Penicillium and Aspergillus were the genera that presented higher number of species, nine and seven, respectively. At the end of the sunflower life cycle, cultivated both in field and in the greenhouse, a lower numbers of species were isolated. One hundred and fifty nine strains of filamentous fungi were isolated from soil and from the sunflower rhizosphere; from these, 79 (49.7%) were able to hydrolyse inulin. There was not significant difference in the proportion of species able to hydrolyse this polysaccharide during the sunflower's life cycle, in plants cultivated in field or in greenhouse. Although the sunflower's rhizosphere is a source of filamentous fungi able to hydrolyse inulin, that might be used in biotechnological processes. This system does not present a higher density of such microorganisms. Species of Aspergillus, Chaetomium, Cunninghamella, Emericela, Eupenicillium, Fusarium, Myrothecium, Neosartorya, Neocosmospora, Penicillium and Thielavia are being related by first time as inulinase producers.
Fungi; rhizosphere; soil; inulinase; sunflower
