Fungal production of the polysaccharide pullulan from a plant hydrolysate

The ability of the fungus Aureobasidium pullulans ATCC 42023 to produce pullulan from hydrolysates of the native grass known as prairie cordgrass was investigated and examined relative to polysaccharide and cell biomass production, yield, and pullulan content of the polysaccharide. A pullulan concentration of 9.7 g l-1 and yield of 0.78 g g-1 was produced by ATCC 42023 when grown for 168 h at 30°C on a phosphate-buffered hydrolysate. The highest biomass level of 7.7 g l-1 was produced by ATCC 42023 after 168 h on a hydrolysate-containing complete medium. The pullulan content of the polysaccharide produced by ATCC 42023 after 168 h on the hydrolysate medium alone was 77%. Unlike what has been observed for other biomass substrates, a polysaccharide with a high pullulan content can be produced at a relatively high yield by a fungus grown on a grass hydrolysate indicating that pullulan could be produced using a biomass-based process.