Purification, Biochemical Characterization of a Macrotermes gilvus Cellulase and Zymogram Analysis

Cellulase plays an important role in cellulose degradation. The enzyme catalyzes the cleavage of b-1,4 glycosidic bond between glucose residues. The Macrotermes gilvus cellulase was purified by using ammonium sulfate precipitation and anion exchange column with 1.38% recovery and 22-fold purification. The SDS-PAGE coupled with zymogram analysis revealed the molecular weights approximately of 54 kDa. The biochemical properties of the enzyme exhibited the optimum temperature and optimum pH of 45°C and 5.2. Interestingly, the enzyme was active over a wide range of temperatures (7-70°C) and a broad range of pH values (4.5-8). At the indicated temperatures and pH values, the enzyme exhibited more than 84 and 50% of its activity. The thermal stability and pH stability of the enzyme were also investigated. The result showed that the enzyme retained nearly 40% of its original activity after incubation in mild acidic (pH 5.2), neutral (pH 7.0) and basic (pH 10.0) conditions for 5 h. The enzyme retained its activity more than 70% of initial activity at both 37 and 45°C after incubation for 3 h. Moreover, the activity of the enzyme was strongly inhibited by Cu and slightly affected by Fe and EDTA, whereas the presence of Ca and Mg slightly increased the enzyme activity. Due to the wide temperature and pH range of enzyme activity, the Macrotermes gilvus cellulase might be potential enzyme for industrial or agricultural application.