Thermophilic Pectinase of Fusarium commune and its Potential Application for Fruit Juice Clarification, Wastewater Treatment and Agrowaste Valorization
摘要
The pectinolytic potential of Fusarium commune isolated from Lathyrus sativus rhizosphere had been addressed. The crude enzyme obtained by growing the isolate in pectin-supplemented Czapek Dox broth showed activities of polygalacturonase, polymethylgalacturonase, pectate lyase, pectin lyase and pectin methyl esterase. Dialysis improved the yield almost 2.5 times with four-fold purification. The enzymes were optimally active at 50 °C, with low Michaelis constant (Km: 2.37–4.83 mg/ml), high maximum reaction velocities (Vmax: 72.33–118.71 U/ml) and activation energy (Ea: 33.99–42.50 kJ/mol). They retained their original activity at 50 °C for 150 min, with their half-life 192–203 min. Ca2+ and Mg2+ stimulated their activities, and β-mercaptoethanol and sodium dodecyl sulphate did not affect their activities. The fruit peels were found to be an efficient substrate for the enzyme. The isolate could use the agro-wastes as growth media with orange peel as the best substrate, producing 1328.56 ± 65.59 µmol of reducing sugar monomer per gram of substrate. When fruit-juice-waste effluent was used as a substrate, the enzyme activity increased up to 38% at 60 min, and it produced 4.4 times the enzyme at 20 days, indicating efficient removal of pectinaceous contaminant from the wastewater. The enzyme-treated juice of grapes and orange showed a significant increase in terms of clarity (> 7%), yield (> 4%) and reducing sugar monomers (> 70%) and decrease of pellet dry weight (> three times) as compared to the untreated control. The enzyme immobilized in chitosan beads activated with formaldehyde showed stability up to 90 days.