In the current study, an extracellular cellulase belonging to symbiotic Bacillus subtilis Bc1 of the leopard moth is purified and characterized. The molecular mass of enzyme was 47.8 kDa using SDS-PAGE. The purified enzyme had optimum activity in temperature and pH around 60 °C and 8, respectively. The purified cellulase was introduced as a stable enzyme in a wide variety of temperature (20–80 °C) and pH (4–10) and remained active to more than 74% at 80 °C for 1 h. Moreover, the cel-lulase extremely was stabled in the presence of metal ions and organic solvents and its activity was increased by acetone (20% v/v), CaCl2 and CoCl2 and inhibited by MnCl2 and NiCl2. The values of enzyme’s Km and Vmax were found to be 1.243 mg/mL and 271.3 μg/mL/min, respectively. The purified cellulase hydrolyzed cellulose, avicel and carboxymethyl cellulose (CMC) and the final product of CMC hydrolysis was cellobiose using thin-layer chromatography analysis. Consequently, owing to exo/endoglucanase activity and organic solvent, temperature and pH stability of the purified cellulase belong to B. subtilis BC1, it can be properly employed for various industrial purposes.

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