Improved [beta]-glucan yield using an Aureobasidium pullulans M-2 mutant strain in a 200-L pilot scale fermentor targeting industrial mass production

(13)-D-glucans with -(16)-glycosidic linked branches are known to be immune activation agents and are incorporated in anti-cancer drugs and health-promoting supplements. [beta]-Glucan concentration was 9.2 g/L in a 200-L pilot scale fermentor using mutant strain Aureobasidium pullulans M-2 from an imperfect fungal strain belonging to A. pullulans M-1. The culture broth of A. pullulans M-2 had a faint yellow color, whereas that of the wild-type had an intense dark green color caused by the accumulation of melanin-like pigments. [beta]-Glucan produced by A. pullulans M-2 was identified as a polysaccharide of D-glucose monomers linked by [beta]-(1[arrow right]3, 1[arrow right]6)-glycosidic bonds through GC/MS and NMR analysis. When a conventional medium was used in the culture of A. pullulans M-2 in a 3-L jar fermentor, [beta]-glucan concentration was 1.4-fold that produced by the wild-type. However, when a medium optimized by statistical experimental design was used with dissolved oxygen at 10%, the [beta]-glucan concentration was 9.9 g/L with a yield of 0.52 (g [beta]-glucan/g consumed sucrose), 2.9-fold that of the wild-type. This level of productivity was reproduced when the fermentation was scaled up 200-L. The industrial production of high [beta]-glucan without melanin-like pigments is highly expected, as a health-promoting supplement or functional food.[PUBLICATION ABSTRACT]