New exopolysaccharides produced by Aureobasidium pullulans grown on glucosamine

The polysaccharides produced by Aureobasidium pullulans, grown using glucosamine as the carbon source, were investigated by means of methylation analysis, affinity chromatography and NMR spectroscopy. The results indicated that, besides a small amount of pullulan, this micro-organism was capable of producing—in low yields—mixtures of at least two different complex polysaccharides containing mainly mannose and galactose. 1H NMR spectra of two fractions obtained by lectin affinity chromatography indicated that one polymer was constituted exclusively of mannose residues while the other contained both galactofuranosyl and mannopyranosyl residues. Polysaccharides different from pullulan are produced by A. pullulans when grown using glucosamine as a carbon source. They are branched mannans and galactomannans. The latter contains galactose in the furanose form.