CHARACTERIZATION OF AN ALKALINE ENDO-POLYGALACTURONASE (PGase LBW 5117) FROM ALKALIPHILIC BACILLUS HALODURANS LBW 5117 AND DEMONSTRATION OF ITS BIO-SCOURING POTENTIAL

Abstract

The demand for pectinases in the global market has been on the rise in recent years due to their significant biotechnological uses. The present study involves the characterization of a crude alkaline pectinase from Bacillus halodurans LBW 5117 and the demonstration of its bioscouring potential. The enzyme was an endo polygalacturonase (PGase LBW 5117) that was brown and had a slight fermentation odor. It exhibited an activity of 0.21 U/ml and retained 67, 90.5, 95.2, and 95.2 % of this activity after 1 year of storage at -20, 4, 20, and 30 oC, respectively. Its operational pH and temperature ranged between 10.2 - 11.0 (optimum, 10.5) and 45 - 57 oC (optimum 50 oC), respectively. Metal ions e.g., K+, Ca2+, Mg2+, Fe3+, Cu2+, Na+, Mn2+, and Zn2+ either stimulated or did not significantly affect its activity at 1 mM. The enzyme retained only 15 % of its activity after 8 h of incubation at 50 oC, but this improved to 200 % in the presence of 1.5 mM Ca2+ and 0.05 mM Tween 20. The enzyme was cellulase-free and hydrolyzed pectin in an endo-manner. Moreover, when used under the established optimized operating conditions, it degraded and eliminated pectin (and other non-cellulosic hydrophobic impurities that adhere to it) from woven cotton (weight loss = 0.68 %) and produced a more hydrophilic fabric with improved wettability for water (drop test = 10 sec) and dye (capillary rise test = 28 mm after 30 min). This result shows that PGase LBW 5117 possesses good operational properties, potentially making it a good bioscouring agent. It is, however, recommended that the bioscouring process be optimized, and its effectiveness be compared with that of standard bio- and/or chemical-scouring process(es).