Secretion of α-amylase and multiple forms of glucoamylase by the yeast Trichosporon pullulans

Abstract

Trichosporon pullulans IGC 3488 produced extracellular α-amylase and glucoamylase activities when grown in batches in a medium containing corn steep liquor and soluble starch or corn starch, α-Amylase, unlike glucoamylase activity, was secreted biphasically. For both amylases the maximum concentration was found in stationary phase cultures. The amylolytic enzymes, previously concentrated by ammonium sulfate precipitation, were separated into a glucoamylase fraction and an α-amylase fraction by Ultrogel AcA 54 gel filtration. Pullulanase activity was located in the glucoamylase fraction, whereas cyclodextrinase activity was restricted to the α-amylase fraction. Isoamylase and α-glucosidase were not detected. Electrophoretic analysis showed that α-amylase activity was due to a single protein. Glucoamylase, however, occurred in multiple forms. The four glucoamylases and the α-amylase were glycoproteins.