Ｃｈａｌａｒａ ｐａｒａｄｏｘａの生澱粉分解酵素とその応用に関する研究

Abstract

The amylase produced by a kind of fungus, Chalara paradoxa, is one of the raw starch digesting amylases. In this report, the studies on properties of this amylase and its application for ethanol fermentation were summarized. There were several glucoamylases (EC 3.2.1.3) in the culture filtrate, and each glucoamylase has a different isoelectric point. These glucoamylases were purified separately, and their general properties were studied. The kinetic studies showed that C. paradoxa glucoamylase has almost the same subsite structure as Rhizopus niveus. But C. paradoxa glucoamylase has rather high affinities for complex cyclodextrins. The raw corn starch granules digested by Ca paradoxa glucoamylase were studied with an electron microscope. The digested starch granules have a layered structure of less susceptibility to the amylase, and there were junctions among layers. In the raw starch digestion, the glucoamylase has cooperative action with the a-amylase (EC 3.2.1.1) which was purified from the culture filtrate. The ethanol fermentation of raw corn starch without cooking using C. paradoxa raw starch digesting amylase was performed. The ethanol yield was more than 90% at proper conditions.