Peat Hydrolysate Medium Optimization for Pullulan Production

Abstract

Peat hydrolysate, a diluted acid-autoclaved extract of peat, was used as a substrate for the production of the extracellular polysaccharide pullulan by three strains of Aureobasidium pullulans , 140B, 142, and 2552. It was found that the addition of (NH 4 ) 2 SO 4 and K 2 HPO 4 as sources of nitrogen and phosphate, respectively, is not necessary for the polysaccharide production. The economically optimized culture medium for large-scale production of pullulan contains peat hydrolysate, 0.05% NaCl, 0.02% MgSO 4 , and 0.01% antifoam FG-10. The initial pH of peat hydrolysate medium is adjusted to its optimum value of 6.0 with Ca(OH) 2 . The total ingredient cost for the production of each kilogram of pullulan with optimized medium is only 1/10 of that with the nonoptimized medium. In this study, a zero cost for peat hydrolysate was assumed, since it is an effluent of the peat and peat processing industries.