Thermostable keratinase from Bacillus pumilus KS12: Production, chitin crosslinking and degradation of Sup35NM aggregates

► A 7-fold increase in keratinase production by Bacillus pumilus was achieved by RSM. ► Keratinase was purified by thermal precipitation with purity of 3.2-fold. ► Enzyme was immobilized on chitin by covalent crosslinking. ► Immobilized keratinase showed better catalytic rate and improved pH and thermostability. ► Immobilized keratinase degraded Sup35NM at pH 7.0 and 37 °C.