Fructose, glucose, and an equimolar mixture of both sugars affected differently hyphae thickness, biomass production and secretion of β-fructofuranosidase in Penicillium janczewskii. Reduced growth, thinner hyphae and visible injuries were early observed during fungal cultivation in fructose-containing medium, reaching the maximum between 12 and 15 days of culture. Total sugar content from the cell wall was lower when fructose was supplied and polysaccharides lower than 10 kDa predominated, regardless the culture age. Maximal inulinase and invertase activities were detected in culture filtrates after 12 days, excepting in the glucose-containing medium. Structural changes in cell walls coincided with the increase of extracellular enzyme activity in the fructose-containing medium. The fragility of the hyphae might be related with both low carbohydrate content and predominance of low molecular weight glucans in the walls. Data presented here suggest changes in carbohydrate component of the cell walls are induced by the carbon source.

A novel antifungal protein with a molecular mass around 50 kDa was purified from seeds of Sesbania virgata (Cav.) Pers. using ammonium sulfate fractionation followed by gel filtration on a Sephadex G-75 Superfine (Sigma) column and reverse-phase high performance liquid chromatography on a C8 column. The protein, designated FP1-A, with a novel N-terminal sequence AMVHSPGG(S)FS(P), showed growth inhibitory activity of filamentous fungi Aspergillus niger, Cladosporium cladosporioides, Colletotrichum gloeosporioides and Fusarium solani.Keywords: plant defence, antimicrobial protein, filamentous fungi, seed protein. Uma nova proteína antifúngica obtida de sementes de Sesbania virgata (Cav.) Pers. (Leguminosae-Faboideae) ResumoUma nova proteína com atividade antifúngica, com massa molar de cerca de 50 kDa, foi purificada de sementes de Sesbania virgata (Cav.) Pers. utilizando precipitação com sulfato de amônia, filtração em gel em coluna de Sephadex G-75 Superfine (Sigma) e cromatografia líquida de alta eficiência em fase reversa (coluna C8). A proteína purificada foi designada FP1-A, com a sequência N-terminal AMVHSPGG(S)FS(P), apresentando atividade inibitória do crescimento dos fungos filamentosos Aspergillus niger, Cladosporium cladosporioides, Colletotrichum gloeosporioides e Fusarium solani.Palavras-chave: mecanismo de defesa em planta, proteína antimicrobiana, fungos filamentosos, proteína de semente.

No abstract