Optimization of Aspergillus niger NRC1ami Pectinase Using Citrus Peel Pectin, Purification, and Thermodynamic Characterization of the Free and Modified Enzyme

Abstract Enzyme cost and stability are the main problems facing industrial applications. Consequently, Aspergillus niger NRC1ami was isolated from rotten orange recorded a promising pectinase activity (13.8 U/ml). The enzyme optimized using citrus peel pectin as sole carbon source (40 It purified by two steps purifications 632 purification folds. pure showed 14.7% carbohydrate content consists of 15 amino acids. Glutamic acid major (22%) followed leucine (10.67%) threonine minor (2.70%). A. conjugated covalent coupling to sodium periodate (NaIO 4 ) activated polysaccharides. Galactomannan highest recovered (85%) 94.34% reduction in viscosity. optimum temperature for shifted 40 45 °C after conjugation process. Also, free its at pH 5 compared 4, form case. thermal greatly improved modification process reduced activation energy 36%, prolonged half-life 5.6-fold 60 °C, increase deactivation (Ed) about 19% comparison form. D value increased 13.2-fold 50 Gibbs's (?G) process, while enthalpy (?H) entropy (?S) decreased. Na + Zn 2+ had stimulating effect on both forms. Graphical