A THERMOTOLERANT fungus Aspergillus fumigatus isolated from agriculture soil, Beheira Governorate, Egypt was screened from other fungal isolates for its high glucoamylase activity. The identification of the fungus based on morphology and sequence analysis of ITS1-5.8S rDNA-ITS2. Five crop wastes (wheat bran, wheat straw, rice hulls, rice straw and broken rice grain) were used to induce the thermostable glucoamylase production by A. fumigatus via semisolid state fermentation. Wheat bran is the most suitable waste for glucoamylase production by the tested fungus which further improved using Plackett-Burman and Box-Behnken designs. Optimum conditions for the production of thermostable amylase are reached at pH 6, wheat bran 1gm, yeast extract 6mg/gm, berij 35 40μL/gm, (NH4)2SO4 24mg/gm and an inoculum of 6x 105spore/ml with thermostable glucoamylase production titer of 161.11U/gm after 6 days.
FeCl3, BaCl2, and CaCl2 positively affect glucoamylase activity with highest main effect value of FeCl3 ions where MgCl2 has the highest negative main effect on activity. The kinetic constants Km is 1.37mg/ml with three bands in zymogram. Moreover the enzyme showed good cleaning effect when applied in starch patches in textile. Glucoamylase of A. fumigatus exhibited good thermostability as it loss only 28.95% from its original activity after treatment with heat at 80°C for 3hr. Finally, the thermostable glucoamylase from A. fumigatus can be produced from cheap agrowaste via simple fermentation technique.