Production and partial characterization of an exopolysaccharide from Ustilago maydis in submerged culture

Abstract

In Mexico, corn is widely cultivated and frequently parasitized by Ustilago maydis, a basidiomycete dimorphic fungus that causes the disease known as corn smut. It is widely consumed and is considered a culinary delight. From a biotechnological perspective, U. maydis offers the possibility as a producer of various metabolites, such as laccase and tyrosinase enzymes, glycolipids, and indole derivatives that can be used in pharmaceutical, cosmetic and food, due to its safety. The exopolysaccharides (EPS) are extracellular sugar compounds synthesized by a variety of microorganism and have shown various properties and applications. Among them are the improved rheology, texture, stability and mouthfeel of fermented dairy products. In addition, these compounds have shown biological activity as an antitumor agent, immune-stimulating and reducing blood cholesterol. The production of EPS by U. maydis was studied by culturing the cells in yeast extractpeptone- dextrose (YPD), YPD supplemented with CuSO₄ (YPD_T), Czapek Dox-sucrose, Czapek Doxglucose, Czapeck Dox culture media with corn steep liquor and in another media containing high oil oleic sunflower as the sole carbon source. The presence of activity of glycosyltransferase by sodium dodecyl sulfate-polyacrylamide gel electrophresis (SDS-PAGE) was detected as well as the polymers formed by dinitrosaliscilic acid (DNS). The products of fermentation were characterized by enzymatic hydrolysis using carbohydrases, gel permation chromatography and atomic force microscopy.

Key words: Ustilago maydis, glucans, polymerization, glycosyltransferase, exopolysaccharide.