Korean Journal of Microbiology, vol. 45, no. 1, pp. 63-68
The exo-polysaccharide producing microorganism, Aureobasidium pullulans IMS-822, was isolated and identified from soil. The viscosity-average molecular weight of exo-polysaccharide was calculated as 8.9×105 by Mark-Houwink equation. The sugar component of exo-polysaccharide was determined as glucose by HPLC analysis. The IR spectra indicated that the exo-polysaccharide has an absorption peak at 890 cm-1 for the β-configuration of D-glucan. The 13C NMR signal at δ 86.62 ppm arose from the substituted C-3 of glucose. The signal at δ 72.11 ppm was assigned to C-6 of branched β-(1→3)-D-glucosyl residues. Viscosity and Congo red reaction indicated that β-(1→3)(1→6)-glucan produced by A. pullulans IMS-822 has a highly ordered hydrogen-bond dependent conformation in aqueous solution, which collapses in strong alkaline solution.