Document Type : Original Article
Authors
1
1Soils, Water and Environment Research Institute, Agriculture Research Center, 12619 Giza, Egypt.
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2Central Laboratory for Environmental Quality Monitoring (CLEQM), Agriculture Research Center, 12619 Giza, Egypt.
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3 Department of Soils and Water, Faculty of Agriculture, New Valley University- Egypt 3 National Committee of Soil Science, Academy of Scientific Research and Technology- Egypt
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4 National Water Research Center (NWRC), Cairo, Egypt.
Abstract
Growing concerns over environmental pollution have necessitated the development of new-generation environmental protection technologies. Multi-enzyme biocatalysts offer a promising approach for reducing pollution caused by organic wastes. However, the recovery of free-form multienzymes is challenging, resulting in high costs and low production efficiency, limiting their application in bioremediation. In this study, we devised a sensitive and stable enzyme biocatalyst by covalently immobilizing multi-enzymes onto nano-silica using glutaraldehyde. Ligninolytic enzymes (laccase, aryl alcohol oxidase, lignin peroxidase, and manganese peroxidase) were produced from Pleurotus ostreatus (NRRL-2366) under submerged fermentation. Enzymes were partially purified through ammonium sulfate precipitation and dialysis. These purified enzymes were immobilized on nano-silica. The resulting immobilized enzymes biocatalyst exhibited stability and activity across a pH range of 4 to 9 and a temperature range of 20 to 55 °C. Immobilization of laccase, lignin peroxidase, manganese peroxidase, and aryl-alcohol oxidase achieved residual activities of 77%, 62.5%, 41.59%, and 28.21%, respectively, after three consecutive batches. Immobilized enzymes biocatalyst effectively degraded p,p'-DDT, and its complete degradation was achieved after incubation at pH 5 and 30 °C for 12 hours, as confirmed by GC-MS analysis. The GC-MS analysis revealed the detection of eleven major metabolites during the degradation process, which were utilized to predict the degradation pathway.
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