Pullulan

Abstract

I. INTRODUCTION Although many fungi are known which overproduce exopolysaccharides with an interesting range of chemical and physical properties [ 1 ], most of the research effort has been directed to the a-glucan pullulan, produced by Aureobasidium pullulans, a fungus with impressive metabolic and ecological versatility [2]. Pullulan, however, is not the only exopolysaccharide synthesized by A. pullulans, which has also been reported to elaborate acidic polysaccharides and several (3glucans [3-7]. Pullulan has never been found inside the cells of A. pullulans [8 ]. Several review articles have been devoted to this polysaccharides [1,9-12] since it was first isolated by Bernier [13] and partially characterized by Bender et al. [14]. Despite this, our present understanding of how its synthesis is regulated, and its role in the biological processes of the producing fungus is far from complete, and a browse through the current literature suggests that pullulan still attracts interest. Unlike the exocellular (3-glucans, which are synthesized by several different fungi [1], only Tremella mesenterica has been reported to produce an a-glucan structurally indistinguishable from that of pullulan [15-17]. However, the fruiting bodies of Cyttaria harioti may also con- tain a pullulanlike glucan [18].