Thermostable Archaeal and Bacterial Pullulanases and Amylopullulanases

Abstract

Pullulanase is one of the industrially important debranching enzymes, capable of hydrolyzing α-1, 6-glucosidic linkages in pullulan, starch, amylopectin, and other related oligosaccharides. It is widely used in starch industry for the production of various sugar syrups. Type I pullulanases specifically attack α-1, 6 linkages in branched oligosaccharides such as pullulan, starch, amylopectin, and glycogen, forming linear α-1, 4-linked oligomers, while the type II pullulanases (amylopullulanases) hydrolyze α-1, 6-glycosidic linkages in pullulan and branched substrates besides α-1, 4-glycosidic linkages in polysaccharides. With the advancements in biotechnology, the application of pullulanase has been extended to pharmaceutical chemistry as well as in automatic dishwashing detergents, baking industry, and production of cyclodextrins. Although pullulanases are ubiquitous in their occurrence in plants, animals, as well as microbes, the microbial sources are the most preferred ones for large-scale production and application. This chapter deals with the developments in production, characteristics, molecular aspects, and applications of microbial pullulanases and amylopullulanases.