Biochemical characterization and stability of Bacillus subtilis polygalacturonase produced using hazelnut shells by submerged fermentation

Abstract

Biochemical and bio-catalytic properties of an enzyme are essential to evaluate its potential industrial applications in food, pharmaceutical, textile, paper and pulp. More specifically, identifying optimal pH and temperature, and their effects on the residual enzyme activity are of high priority in biochemical characterisation. Therefore, in this study, polygalacturonase (PGase) produced as an extracellular enzyme in an earlier study growing Bacillus subtilis on hazelnut shell hydrolysate was evaluated under varying pH and temperature for its stability. The optimal pH and temperature values of the enzyme were found as 7.0, and 50 °C, respectively. The enzyme K_m and V_max values were identified as 0.52 mg/mL and 3.27 μmol/min. The enzyme retained about 93 and 78% of its initial activity at 50 and 60 °C after 7 h, respectively. SDS-PAGE revealed a single activity band with molecular weight of 50 kDa. The half-life of PGase at 50 and 60 °C were 57.8 and 23 h, respectively. Thus, the results prove the potential of the B. subtilis pectinase produced using hazelnut shells in food processing e.g. extraction and clarification processes or treatment of pectic waste water.

Keywords:

• pH stability
• thermal stability
• polygalaturonase
• hazelnut shell hydrolysate

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by METU Research Council (project number is BAP-03-14-2011-002) and the Graduate School of Natural and Applied Sciences at the Middle East Technical University, Turkey.