Characterization of a Novel Thermophilic Endopolygalacturonase Produced by Bacillus licheniformis IEB-8

Saqib Hussain Hadri, Muhammad Javaid Asad, Muhammad Zeeshan Hyder, Syed Muhammad Saqlan Naqvi, Tariq Mukhtar, Muddassar Zafar, Shahzad Hussain Shah, Raja Tahir Mehmood, J. H. David Wu


Endopolygalacturonases characterized until now have either low working temperatures, working pH in acidic range, high Michaelis–Menten constant (Km), or a high production cost. These characteristics are a hurdle in the industrial applications of these endopolygalacturonases. The purpose of this work was to characterize a novel endopolygalacturonase produced by Bacillus licheniformis IEB-8. Phylogenetic analysis of Bacillus licheniformis IEB-8 showed that the isolate was unique. Citrus peels were used as the only nutrient source for the growth of Bacillus licheniformis IEB-8, allowing a cheap production of endopolygalacturonase. All the synthetic carbon sources showed a negative impact on the production of endopolygalacturonase, while ammonium sulfate enhanced its production. Among different metal ions, Zn+2 showed a negative effect while Mg+2 and Ca+2 did not have any significant effect on the endopolygalacturonase activity. A Lineweaver-Burk plot was prepared for the characterization of the kinetic parameters including Km and Vmax, which were 0.45 mg/mL and 285.7 µM/min, respectively. A comprehensive comparison of the endopolygalacturonase from this study with the available literature indicated that it is better than the reported and commercially available endopolygalacturonases in having the optimum working temperature of 55 C, a low Km of 0.57 mg/mL, and pH of 7 to 8, which indicated its novelty.


Endopolygalacturonase; Bacillus licheniformis; Thermophilic; Phylogenetic tree; Kinetics

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