A new variety of Aureobasidium pullulans characterized by exopolysaccharide structure, nutritional physiology and molecular features

The black yeast Aureobasidium pullulans (de Bary) Arnaud is known to synthesize the exopolysaccharide pullulan, a poly--1,6-maltotriose. Nine strains were found to produce additional aubasidan-like EPS, i.e. glucans with -1,4-D-, -1,6-D- and -1,3-D-glycosidic bonds. These strains had previously been found to deviate in genotypic characters. Additional physiological differences were found: the optimal nitrogen source for exopolysaccharide production in liquid medium was NaNO₃ for aubasidan-producing strains, and (NH₄)₂SO₄ for the remaining strains. A new variety, A. pullulans var. aubasidani Yurlova, is described for the strains producing aubasidan-like components. The new variety can be distinguished from A. pullulans var. pullulans by the absence of assimilation of methyl--D-glucoside and lactose.