Effect of pH and Its Optimization for High Molecular Weight of Pullulan

Abstract

Pullulan is a polysaccharide produced by Aureobasidium pullulans. Though molecular weight of polysaccharide is an important parameter characterizing the physical properties of the polysaccharide [1], little work has yet been published relating to the effects of operating parameters on the molecular weight of pullulan. Catley [2] reported that the molecular weight of pullulan cultivated at initial pH 6.6 was initially 2,000,000 and it reduced to 200,000 after 3-4 days. The reduction of the molecular weight with an increase in cultivation time was also reported by Wiley et al. [3] Kato and Makoto [4] reported that the molecular weight of pullulan was 200,000 at initial pH 7.5 and 2,000,000 at initial pH 5.5. In this study, the effect of pH on the molecular weight of pullulan was investigated.