Production of a novel raw-starch-digesting glucoamylase by Penicillium sp X-1 under solid state fermentation and its use in direct hydrolysis of raw starch

Penicillium sp. X-1, isolated from decayed raw corn, produced high level of raw-starch-digesting glucoamylase (RSDG) under solid state fermentation (SSF). Maximum enzyme yield of 306.2 U g(-1) dry mouldy bran (DMB) was obtained after 36 h of culture upon optimized production. The enzyme could hydrolyse both small and large granule starches but did not adsorb on raw starch. The enzyme exhibited maximum activity at 65 degrees C and pH 6.5, which provided an opportunity of synergism with alpha-amylase. It significantly hydrolysed 15% (w/v) raw corn starch slurry in synergism with the commercial alpha-amylase and a degree of hydrolysis of 92.4% was obtained after 2 h of incubation.