Polysaccharides from basidiomycete Rhizoctonia solani biomass: extraction, purification and characterization

• Grant number: 11/13088-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2011
• End date: November 30, 2012
• Field of knowledge: Biological Sciences - Biochemistry - Chemistry of Macromolecules
• Principal Investigator: Maria de Lourdes Corradi Custodio da Silva
• Grantee: Samara Marrye Aguiar Alexandre
• Host Institution: Faculdade de Ciências e Tecnologia (FCT). Universidade Estadual Paulista (UNESP). Campus de Presidente Prudente. Presidente Prudente , SP, Brazil

Abstract

Considering that the fungal mycelium can be an important source of chemical compounds, including polysaccharides, the knowledge of the structure and biological activity of such molecules may contribute to the practical and rational use of biomass produced from the cultivation of the microorganism. This work will study the biomass of Rhizoctonia solani, grown in laboratory. To obtain polysaccharides from biomass it to be washed with distilled water thoroughly until no detection of sugar by phenol-sulfuric acid method, ensuring the complete removal of exopolysaccharide. The mycelia mass will be dry, fragmented and subjected consecutively to three different procedures of extraction: cold water (3x), boiling water (3x) and 2% potassium hydroxide solution (1x). These extractions will separate the biomolecules into groups according to their solubilities. Purification of polysaccharide extracts will be made by repeated freezing and thawing, precipitation by formation of soluble and insoluble complex Cu2 + (precipitation with Fehling's solution) and gel filtration chromatography, among others. The purification steps will be monitored by chromatographic profile obtained by gel permeation chromatography and refractive index detection. This technique will also be used to determine the molecular weight of polysaccharides by comparison to dextran standards. Since the structural characterization of polysaccharides is important to understand the biological effects displayed by this class of polymers, this research also aims at structural elucidation of polysaccharides using conventional chemical techniques such as hydrolysis of carbohydrates, methylation and nuclear magnetic resonance of proton and carbono. (AU)