| Summary: | Thermophilic endoglucanases have become of significant interest for effectively catalyzing the hydrolysis of cellulose. <i>Myceliophthora thermophila</i> is an ideal source of thermophilic enzymes. Interestingly, different hosts differently express the same enzymes. In this study, we successfully overexpressed endoglucanase (<i>Mt</i>EG5-1) from <i>M. thermophila</i> in the methylotrophic yeast, <i>Pichia pastoris</i> GS115, via electroporation. We found that purified <i>Mt</i>EG5-1 exhibited optimum activity levels at pH 5 and 70 °C, with 88% thermal stability after being incubated at 70 °C for 2 h. However, we observed that purified <i>Mt</i>EG5-1 had a molecular weight of 55 kDa. The Km and Vmax values of purified <i>Mt</i>EG5-1 were approximately 6.11 mg/mL and 91.74 μmol/min/mg at 70 °C (pH 5.0), respectively. Additionally, the optimum NaCl concentration of purified <i>Mt</i>EG5-1 was found to be 6 g/L. Furthermore, we observed that the activity of purified <i>Mt</i>EG5-1 was significantly enhanced by Mn<sup>2+</sup> and was inhibited by K<sup>+</sup>. These results indicated that <i>Mt</i>EG5-1 expressed by <i>P. pastoris</i> GS115 is more heat-tolerant than that expressed by <i>A. niger</i> and <i>P. pastoris</i> X33. These properties of <i>Mt</i>EG5-1 make it highly suitable for future academic research and industrial applications.
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