Three exopolysaccharides of the ?-(1->6)-d-glucan type and a ?-(1->3;1->6)-d-glucan produced by strains of Botryosphaeria rhodina isolated from rotting tropical fruit.
Vasconcelos A. F. D., Monteiro N. K., Dekker R. F. H., Barbosa A. M., Carbonero E. R., Silveira J. L. M., Sassaki G. L., Silva R. da, Lourdes M. de, Silva C. da
Author Affiliation: Departamento de Física, Química e Biologia, Faculdade de Ciências e Tecnologia, Universidade Estadual Paulista, C.P. 467, CEP 19060-900, Presidente Prudente, São Paulo, Brazil.
Carbohydrate Research 343 : 2481-2485
Abstract : Four exopolysaccharides (EPS) obtained from Botryosphaeria rhodina strains isolated from rotting tropical fruit (graviola, mango, pinha, and orange) grown on sucrose were purified on Sepharose CL-4B. Total acid hydrolysis of each EPS yielded only glucose. Data from methylation analysis and 13C NMR spectroscopy indicated that the EPS from the graviola isolate consisted of a main chain of glucopyranosyl (1->3) linkages substituted at O-6 as shown in the putative structure below: The EPS of the other fungal isolates consisted of a linear chain of (1->6)-linked glucopyranosyl residues of the following structure: FTIR spectra showed one band at 891 cm-1, and 13C NMR spectroscopy showed that all glucosidic linkages were of the ?-configuration. Dye-inclusion studies with Congo Red indicated that each EPS existed in a triple-helix conformational state. ?-(1->6)-d-Glucans produced as exocellular polysaccharides by fungi are uncommon.