Pullulan production by Aureobasidium pullulans growing on hydrolysed potato starch waste

Enzymic hydrolysis of potato starch waste yielded a substrate suitable for growth and exopolysaccharide production by Aureobasidium pullulans. Hydrolysates produced by alpha-amylase alone gave the lowest yields of exopolysaccharide with a low proportion of pullulan. Continued hydrolysis with pullulanase and amyloglucosidase gave higher yields with a better proportion of pullulan, but prolonged hydrolysis did not improve the yield further. The oligosaccharide composition of the hydrolysates was determined by capillary electrophoresis following reductive amination with ethyl p-aminobenzoate, Maltose-rich hydrolysates, generated with beta-amylase and pullulanase, yielded over twice as much pullulan as the corresponding glucose-rich syrups generated with amyloglucosidase and pullulanase. It is concluded that the composition of the starch hydrolysate is important in determining pullulan yield. (C) 1999 Elsevier Science Ltd. All rights reserved.