Ascorbic acid stimulation of production of a highly branched beta-1,3-glucan by Aureobasidium pullulans K-1 - Oxalic acid, a metabolite of ascorbic acid as the stimulating substance

The production of a highly branched beta-1,3-glucan by Aureobasidium pullul ans K-1 in Czapek's medium has been found to be stimulated by ascorbic acid . When the culture supernatant, after removal of polysaccharide from the cu lture filtrate by ethanol precipitation, was concentrated, then added to a new medium and this strain was cultured in the medium, the polysaccharide p roduction was stimulated the same as when L-ascorbic acid was added to the medium. The stimulating substance was partially purified from the supernata nt, and was found to be oxalic acid; 0.03% oxalic acid was the most effecti ve concentration for the stimulation of polysaccharide production. The stim ulating substance, oxalic acid, was proved to be derived from ascorbic acid added to a medium in an experiment using L-[1-C-14]ascorbic acid. We sugge st that oxalic acid generated from the metabolism of ascorbic acid in cells of Aureobasidium pullulans K-1 participated in the stimulation of the poly saccharide production by ascorbic acid.