Isolation of a transglucosidase-nonproducing mutant ofAspergillus awamori yielding improved quality and production of amyloglucosidase preparations

Summary The fermentative production of amyloglucosidase (AMG) by differentAspergillus species simultaneously yields transglucosidase (TG), which is undersirable in the conversion of starch to dextrose, as it catalyses the reversion of dextrose and maltose to maltosaccharides, in turn providing disproportionately lower yields of dextrose (DX). To overcome this problem, using UV-irradiation, a novel mutant (ND-1-283) has been isolated fromAspergillus awamori, which has lost the ability to produce TG and which secretes 45% more AMG than its parent strain, giving the mutant a dual operational advantage. The inability of this mutant to produce TG was demonstrated by thin layer chromatography (TLC) of starch hydrolysate; this was substantiated by obtaining 96.0% DX (w/w) at the end of saccharification.